RSGo Competition: rsgochampionship.com/ Disclaimer: I am NOT an engineer. I DO NOT know everything. This video is presented to the best of my knowledge at this point in time. If I've made errors, please educate me instead of spitting hate. Thank you. FPVCycle 2203: bit.ly/3i7QPuA CineSplore: bit.ly/3dGJu1z (back in stock in ~11 days) Gemfan Duct props: bit.ly/385nvAk 30A 4S AIO Toothpick board: bit.ly/3i8POCq PowerPick: bit.ly/3fW6iMq Longer Vista antenna - bit.ly/2ViXhFg Vista + Nano Nebula - bit.ly/2ViXhFg Vista kit + longer camera wire - bit.ly/2ViXhFg 200mm DJI camera wire - bit.ly/3eyBYXU More things coming soon to FPVCycle.com Table of Contents: ►00:00 - Intro ►04:25 - Example of issues on higher voltage ►07:25 - Comparison of 4S vs 6S ►12:58 - Basic electromagnet overview ►14:45 - Moving from 4S to 6S, current drop ►17:29 - What voltage does to torque ►21:55 - When do you need more volts ▼Join my FB group for more discussion: Kabab FPV facebook.com/groups/379155946182689/ The store: www.FPVCycle.com ▼ My typical 5" quad setup: -CineGlide: bit.ly/2MCoz50 -Motor: bit.ly/2Nqqr25 -ESC: bit.ly/2oDdzvL -WaFL’s Cap Cap: bit.ly/2GUpXxO -Battery: bit.ly/2JnsTDM -FC: bit.ly/2XRc8G8 -FPV Cam: bit.ly/2Q7LfL7 -Vtx: bit.ly/38Y25oz -ND GoPro Mount 30deg: bit.ly/2WC15zc -ND Filter (if used): bit.ly/2WEmQ1j ▼Notable motors: Check out the Rcinpower Wasp and Bison...interesting motors coming. We're working on blending those two motors into one. The Wasp is more powerful but the Bison has an awesome 11mm bearing that's uber smooth. ▼Starter goggles: bit.ly/2qbJNOS ▼ If you want to solder better: -Fantastic solder: amzn.to/2P5QM2W -Fantastic iron: goo.gl/DqBipa ▼ Tips? Patreon: bit.ly/2oGLP9b -PayPal: www.paypal.me/kababfpv -Bitcoin: 1E4XZXoD4rS6MYWVWuenY7Kw2M1YgyNpoQ -Nano: xrb_1188ek5bd7tb9kw67asnp9o65byuoaxbtpxuznx1ribf75x78awywmakj55f -ETH: 0xD067F93811f2eC31CB1928901002dfdf9A492EF5 -LTC: La2KWYAjp4VT2Lq2M76pbjzXWvRyjpfCtG
@KababFPV Increasing current flowing through a wire, does increase electron flow, producing a stronger magnetic field. However, that assumes the exact same wire, with the same length. A magnetic field is produced along the entire length of the wire. Therefore, a wire 1m in length, with 10A passing through it, would produce an equivalent overall magnetic field as a 2m wire with 5a passing through it. As you go down in kv, the number of turns on each pole has to increase with all else being equal, increasing the length of the wire proportionally. Additionally, the resistance of the wire does increase proportionally as you either lengthen it, or reduce the cross sectional area of the conductor, or both as is the case of a lower kv winding. A lower kv winding will have a thinner (smaller conductor cross section), and longer wire, with more turns. This will produce a higher resistance per phase. The higher or lower resistance will not directly effect the magnetic field, however will increase or decrease the amount of current that will flow for a given voltage. Theoretically, If a 2306 motor, with 8 turns per pole, resulting in a 2700kv motor (this is actually the result I got on a 3b 2306 motor) Then a theoretical 16 turn winding would result in somewhere around 1350kv winding. This motor would require half the current to produce the same magnetic field as the first 2700kv motor. Twice the number of turns, with twice the length of wire. There are a few problems with this scenario I can see though. Kv does not scale linearly with the nr of turns, as well as other practical implications. eg. when you increase the number of turns, the turns are wound over the initial ones, placing the copper further from the core, and the magnetic field becomes less effective. Perhaps Ryan Harrelll could give us some insight on this?
Excellent thoughts Darren. It gets more complicated with skin effects, particularly as they relate to near-saturation states as winding count and actual flux gets interesting at that point, which is why the lower KV from higher turn count doesn't just jump higher.
For the very limited scope of the concept that you were trying to convey, your presentation was dead-on simple physics. The movement of electrons in a conductor (a current) creates a magnetic field. If you curl the wire multiple times around a cylinder made of a ferromagnetic material (a nail) it will produce a magnetic field stronger than it would be if the material were not there. You can prove this quite easily by wrapping wire around a nail, preferably a thick one, but that’s not even a requirement. A regular 8 or 10 penny nail will participate even if the wire is wrapped quite haphazardly around it. You can amuse yourself (and your friends) by hooking it up to an old-style dry cell and picking up small metallic items quite readily. If you wrap more wire around the nail (or increase the current) you can pick up even larger things. Your explanation as I understood it, was simply to convey the concept that electricity flowing through a wire, around a magnetic form (regardless of the shape) or not, which varies in the amount of current flow from moment to moment will create a magnetic field which varies in strength with respect to the current flow. This is what an ESC does; it modulates the current flow in the magnetic coils of a motor, in response to signals from the Flight Controller, to make the motor turn faster or slower as a result. Because it is able to do this at incredible speed, the motors can be made to respond to very slight changes coming from the flight controller of varying amounts for each of the 4 motors in a quadcopter simultaneously . Without our ability to produce the complex hardware to do this, we would not be able to fly our craft the way we do. Yes, there are amazing engineering challenges to making this happen, but the concept remains simple without any need to get inductance effects, much less eddy currents or skin effects. Like I said the first time...you did great!
I'm an engineer and im trying to ELI5 for your readers. The problem is motor inductance. There must be a equilibrium between motor inductance and voltage/current. Low inductance (=high kv, small size) have too fast response to the voltage steps provided by the esc, and the current is erratic and difficult to control, and might even reverse during a commutation cycle.
From what little I understand, this is currently managed by a faster processing to keep up with the switching better. But yeah that's the issue with high kv high power and I suspect is part of why I'm having issues with the quad in the video....which is why 3S is fine on it.
Having played with COMSOL, this really shakes out to switching related EMI bleedover, not necessarily any wobbles. Higher PWM frequency, reduced rampup power deltas, and then the actual motor inductance/capacitance, but they tend to be fairly lossy in that regard (a good thing), but this is why the excessively high KV setups see worse EMI, particularly when at the top end extremes, or when fed any amplifying oscillations.
Now, exclusively at FPV Cycle a new flexible scale toothpick quad "The Singularity"! Bob R caption: "I do not claim to have invented the toothpick quad, but I may well end them as we know it"
KabaFPV, I think you missed a little point in the magnetic field explanation. Yes, field is proportional to current, but ALSO to the number of windings. The KV number is inversely proportional to the Inductance of the winding, which in turn is dependant on the number of windings (I think proportional to N²). 6s means lower KV, which means more turns, which means less current for the same field strength but more resistance, which is where the higher voltage comes into play to theoretically balance it. I think the reason why it doesn't balance itself is, that field strenght is proportional to N, while inductance is to N². Would be cool if someone checked that, who's better at math than me...
I know this through many discussions and a few others have pointed it out as well. I believe this is at least in part why we don't need a whole lot more kv to adjust 6s into feeling better but I don't know by how much. I choose to leave this out because I don't know how much effect it has. Just choose to keep it as basic as I could which I know is not the whole story but the more I learn the more I know I don't know anything....will I ever know what's actually going on 🤷🏻♂️
@@Kabab "...will I ever know what's actually going on" Probably not, we cant even fit gravity into the standard model of quantum physics. Its going to be a while.
That explain why most people prefer 2207 on 4S and 2306 on 6S too. Very interesting video, thanks for taking the time to explain to us plebs with simple words !
Yes the wider motors shift the torque curve down again. But not as much as voltage shifts it up.....this is the premises I'm working on for a new motor....didn't want to give away too much.
@@Kabab I mean as u used the 4s on it, it was making noise. Will it always make that noise? Or is it due to noise in gyro which in result is causing the noise in the motor?
Honestly, Bob, that's precisely why I didn't go to 6s. And I won't, at all. It makes no sense, exactly because of the current. I tried to explain this back then when people were debating 4s vs 6s, but nobody would listen. 😕 I remember I commend in a video, maybe it was on your channel, I really don't remember, and a lot of people come to say I was wrong without any argument. So... I shut up. BTW, I really hope it doesn't happen here again. I don't have any patience for debating on the internet anymore. 😕 Anyway, stay safe there! 🖖😊
Interesting info here, thanks Kabab. I started on (edit:1500mah) 4S, 2207 2500kv. I was always in a rush to build a 6S rig because of all the videos claiming longer flight times, less sag etc. When I finally built up my 2306.5 1850kv, on 1100mah 6S I was actually getting SHORTER flight times (Both at about 625g with Session5). I also found it's harder to find good performing, lightweight 6S batteries. My $46 Thunderpower 1100mah battery flies like a dream and is lightweight, but my $28 1000mah GNB is super heavy, and gives me short flights with sag comparable to 4S. I've found the 1250mah 5S from pyro is one of the lightest packs that gives me 5+ minutes of freestyle flight, minimal sag, and I fly it on a 88% motor output limit on the 2207 2500kv. That is my go to for the "4S" quad. It seems I just have to cough up some more cash for the good batteries to get comparable performance on my 6S build.
Your experience is not unique unfortunately. The people claiming so much more flight time are using batteries that are way bigger than the equivalent 4s so of course it's going to have more flight time. But overall, 6s is actually less efficient.....but better voltage stability and improved electrochemistry condition.
Just for historical perspective. Years ago, we used to run wimpy Gemfan 5030 bi blade props. Then everyone got excited about heavy bull nose props, then tri blades, etc. Ppl were trying to get more thrust by just beefing up the props, and not thinking about the efficiency of the motors. So motors and voltage isn't the whole story. Lots of guys kept everything the same and just started flying heavier, more aggressive and less efficient props (also just cause those props were more durable). I think prop tech is just as important as everything else in these equations. Do you want to punch out to the moon and kill your battery in 20 seconds, or do you want to fly smoothly for 3 minutes with consistent power, and your props are much more fragile. But material science has also come a long way. I remember flying Gemfam 2 blade 5030s that would all completely explode on a rough landing. Props are a big part of this story
why does kabab say that 6s feels worse and is less linear? When everyone I know who flies 4s and 6s freestyle says 6s feels better and is faster and lasts longer
@@cinialvespow1054 It depends on how you fly I guess. I can see how someone who flies aggressive freestyle with fast punch outs would benefit from 6s more as you get less sag and also higher peak rpm considering how we usually run higher kv motors for 6s than 4s equivalent. However for someone who prefers mellow freestyle and maybe slower proximity flying, more linear power delivery on 4s might be an advantage over 6s. That's just how I see it.
I built 5s and 6s quads, I really do fly my 5s quads more often since they are more controllable and easily tuned. I have tuned one to where you could barely hear the props in flight. That quad dose fly 7 to 11 mins without a GoPro with 1050 5s. I do give the battery time to recover in flight if I do flip flops, or race style flights. I wish Betaflight would have 1 Gauge for RPM like how regular vehicles have the RPM gauge from 1 to 9. But I do enjoy you’re videos. Can’t wait to see whats next ✌🏼
Really what you're after is a strain gauge to indicate how many Amperes the craft is drawing out of the maximum. This would be difficult to reasonably calibrate, but we could get close with the following example: Say at *16.0V* your quad pulls *100A* & at *13.6V* it pulls *85A* .We create a linear scale using these points, then measure instantaneous voltage and current then compare it to the scale. Your quad is cruising at *18A* , battery voltage is reading at *14.8V* . *14.8V* is *50%* along your voltage scale, meaning we can estimate max amps to be exactly between *100A* + *85A*, or *92.5A* . We take your cruising current of *18A* and divide it be the _theoretical max_ of *92.5A* and that gives us a "strain" _estimation_ (more on this below) of *~19.5%* Your "RPM" gauge of 1-9 would then show *1.75 "revs"* if you count *0* as the lowest or *2.5 "revs"* if *1* was the lowest. Now, _why an estimation_ you ask? Because this scale would sadly not be linear - the LiPo chemistry doesn't work like that; Supplying 20A is *MORE than twice* the work for a battery than 10A and the battery will output less useable power overall. This only gets worse the more Amperes you draw. Again, we could make some simple observations and apply a rough fudge-factor to approximate this, but getting it to any reasonable degree of accuracy would require testing and calibration for each individual battery throughout it's lifespan due to the ever-increasing internal resistance. On the other more simple side, you can also display the current throttle stick position on the OSD. This is *not* equivalent to an "RPM" gauge, in car terms that would show how far the accelerator was depressed. It would simply show the *requested* power not the _actual_ power. Hope this helps give you some stuff to consider in your quest for an OSD rev gauge :)
@@JustInvertedFpv with bidirectional Dshot you can actually show all 4 individual motor speeds on the OSD. I'm not entirely sure why you'd want that but it's doable :D
I'm Not an engineer, but I play one on TV. LOL. The erratic movement you are seeing in the motors is the same thing I see anytime I run a quad with props off. It is only more amplified to the naked eye as you increase voltage, giving the PID more authority. The default PID's on most firmware is set to expect the resistance of the props. You could stabilize the erratic behavior of the motors by dropping P gains in the software, but then the quad would not fly very well with props on. Run the same test, outside, away from you, with props on at idle. I think you will find that the default PID's are very stable when they are run with the load they are designed for. The PID Loop is trying to reach a goal over time (RPM or Axis angle of the quad) as set by the software. Example is, If the PID Loop is set to try a certain amount to reach it's goal within a certain time with props on, when you take the props off, it will get there too fast and have to slam on the brakes because it will "overshoot" the target. Because it can't learn on it's own that it is doing this, it will do it over and over again, causing erratic behavior. Let's say you added really heavy props or props with an aggressive pitch. The motors would be more stable but very sluggish until you command the PID's to try harder to reach that goal. The key I have found through people way more experienced in this is than I am is, Match your max prop RPM's in your 6s build as close as you can to max RPM in your 4s build. 4s is 4.2 volts x 4 series cells right? so 16.8 volts fully charged. With a 2450kv motor, we are looking at a max RPM of 2450rpm x 16.8volts. So 41,160 RPM. Now Lets build a 6s quad that we intend to behave in almost the same way. 6s is 4.2 volts x 6 cells. So thats 25.2volts. Take the max Rpm from the 4s build and divide it by the voltage of 6s. So 41,160 divided by 25.2 is approx 1,633kv for the motor. I've never seen a 1,633 motor before so I would try to get close by getting a 1700kv motor. After making these changes to a 4s quad (Keep in mind that all electronics on the quad must be rated to run at 25.2 volts or above to keep from frying them) you should be able to run 6s on your 4s settings with very little adjustment needed because the max RPM is going to be about the same. The difference in the 6s build is that is is relying more on the voltage to spin up the motors than the capacity of the battery. On a 4s full throttle punch, the voltage drop is faster and then you are in the capacity area of the battery sooner. A 6s battery has higher voltage and more cells to sustain the load so voltage drop is more preventable. We don't stay in full throttle very long but some of us just want a little more than we get out of 4s and 6s seems to provide that. Some have said that moving to a 6s setup gives much longer flight times as well due to battery having better voltage "bounceback" or recovery after a throttle punch. I have noticed this myself and really enjoy the benefits. That's my 2 cents. Be safe and responsible out there guys. Don't get the rest of us in trouble by flying like a moron! Thanks.
LOL. I should have waited until my internet connection came back and I could watch the rest of the video before commenting. Awesome video KABAB! Thank's for your contributions to the hobby sir!
Very informative video, thank you! I noticed that Gemfan gives (very) similar information on 5125 prop at Banggood. Just one thing, you didn't mention the different amount of coil turns that different kv motors have. If I'm not mistaken more turns (found in lower kv motors) can make an electromagnet stronger. Please correct me if I'm wrong and again thanks for the video!
Yes and no. More turns means less current is needed to create the field but you need more current to saturate the stator. Less turns will have faster moving current....it's ultimately about the same but the difference with higher kv is that the field strength rate of change is faster because it ramps up faster.
Reminds me of the argument, do you need an amplifier to use with your headphones? And then the trend and technologies evolved to remove the headphone jacks...
Cell phone Mini head set Amp sitting on my shelf next to my desk .. Thinking about adding it to the desktop workstation and seeing if it blows my puter speakers
I personally fly 4s. Have never tried 6s, ive just never found a reason to go 6s. At first i was thinking to switch once i broke a motor, my BrotherHobby motors havent broken in 15months, so im going to stay hsha. I am very happy with the performance, i get 5-6 minutes of mixed flight with a satisfying amount of top speed. There is a slight sag at the very emd of the battery but i am a casual freestyler so i dont mind 👍
I honestly was experimenting with low KV longer flight time maybe 6" arms and 6" props but I'm seeing no diff yet Ironically I was just about to order a bloat of 6S batteries .. LOL
Definitely on to something here. Shawn Ames is doing something interesting with his Freedom Spec race, coming up on the fourth. But the most interesting thing being that battery is set as 3S.
This is one of the most interesting discussions I've watched from you. I don't know why. Until now, I've really never understood why using equivalent kV to 4S on 6S doesn't work well. Great video!
This is fascinating. I wonder if you can use a regulator to limit the voltage and then "shift gears" to a higher voltage to help provide the most torque possible. Obviously the biggest issue with this is the kv would then have to be variable as well. Honestly I don't understand how kv is implemented into the construction of the motor. Is it the coil amount? The gage of wire? Magnet size? I actually don't know. But I fear it can't be variable which could destroy my "gear shifting" idea.
Equivalent 6s to 4S motors are same speed but it's the total WATTS output power that counts. A 6s setup will run cooler and more efficient at same speed to 4s. It's at about volts X amps
That these gyros meant for phones (very optimized current draw), that work by very precisely vibrating a nano scale mass, and then very precisely measuring the difference that's crated by moving moving it. That this still works when the gyro is on the same PDB as 4 extremely tightly packed, creatively component reduced ESCs, is kinda ridiculous.
The magnetic field strength is proportional to Ampere*turns, not current-only. Force/torque is proportional to the field. A 1000kv motor needs twice the number of turns on a stator pole compared to a 2000kv motor with the same construction. Thus, 20 Amps through the 2000kv motor produces as much torque as 10 Amps through the 1000kv motor. There is a catch though. Winding inductance, and therefore the ability to change current/motor torque quickly, increases with number of turns squared. A single stator winding on that 1000kv motor therefore has four times the inductance of the winding in the 2000kv motor case. But current must ramp to half of it to produce the same amount of torque. So it is 4/2 = twice as 'sluggy' as the 2000kv motor. Maybe that is the reason why we prefer higher kv on 6S?
Very very helpful. Totally forgot about that but makes total sense. So it's probably a combination of them which is why we don't need a whole lot more kv. Just a bit more to make it feel closer to 'right'
The issues you explain going from higher s to 3s to me seem to come from the higher gain in the feedback loop. Your pid settings are the same... But the motor response increases the mechanical gain in the loop because the motors have more torque which has to be compensated for in the software pid. Lowering the total gain will probably solve it. I'm an engineer :) but really new to betaflight and drones in general so I might also be entirely wrong :)
In the case of this particular quad what I believe is happening is entirely noise in the system and the increased voltage is just exaggerating it. Never mind the quad. I was just using it to show how things can suck on higher voltage. Nothing more. I'll fix tht noise issue on the quad.
Thank you very much but we're trying to make this work without raising money. margins are so darn slim it would mean we'd be working for someone else for zero pay.
Great video. Amps kill if relatively little voltage is present. Volts with relatively no Amps just make you flop like a fish (taser) or make your hair stand on end (electrostatic generator). The right combination of the two is what make the lights come on (Watts). I relate electricity to fluid mechanics in that Voltage is a pump or vessel of stored energy. The size of the vessel is its capacity(mAH). Amps is the size of the pump lines or how fast that energy can flow. There is of course resistance (Ohms) which affects the flow of that current. The difference between fluids and electricity is fluid is not compressible. If you want more pressure you need a bigger pump. Voltage however, through a capacitor, is compressible. That is why Quads need a Cap to meet the high current demand and minimize voltage sag. The marriage of volts to amps is as equally important as props to motors. Long track racers need the top end while the short tracks would need the quickness off the line and between the gates. This same discussion can apply to Inline 6 vs V8 engines. The I6 is insanely quick off the line but does not have the torque or HP of the V8. I think the long and short of it is: what is the weight/size of the Quad, what do you want it to do with it, and how long do you need to do it. That would be an interesting video. Compare size/weight class with different battery/motor/prop combos on both long and short tracks. Thanks for your work.
High voltage is being used because for the same amount of power you need less current. That results in smaller ESCs and cables needed making the quad lighter and cheaper.
Except that the ESC is actually larger as heavier. We don't go smaller and lighter typically when we get more potential wattage output. We just use the wattage to go faster....this is performance flying. Not dhi float around flying
Great video. Thank you Kabab for sharing your learning and experience. You may have just solved a problem I'm currently facing. Been trying to get motors designed for 4S to work with 5S, and likely pushing the motors too hard as a result.
You forgot one thing! A higher number is better! 6 is 150% of 4, so it just HAS TO BE 150% better. Go away with all your fancy "maths" and "experience". Just kidding of course. Love the video, very interesting
Thank you for this well explained and logical journey to explain your thinking. I learnt lots and also forms a base to help make build decisions going forward! Look forward to the continuation of your research👍🏻 great stuff..love how this hobby makes your your head spin when youre flying and when youre not!
Another thing that 6s over 4s is because of the lower temperature from lower amperage the electronics run smoother. When I was doing my run to hit 145mph back in spring of 2017 my main issue was melting motors and soldering joints. Switched to higher rated connectors then to 6s to lower the temperature of the electronics and the solder joints. APC and the other prop companies at that time all told me that they design the top speed of there props to be 25000rpm +/-1000 max. The props start loosing efficacy and the ability to hold there shape. I was running 2306 2750kv on 6s to hit 145mph.
Well yes but if you wanna get tht torque back then you need higher kv which drives the current and because you have higher kv and more voltage you get more rpm which draws more current....so as long as you keep it lowish on the throttle it's less heat.
@@Kabab true but for all out speed runs which are 100% throttle aerodynamics and temperature are most of the issues i have. 145mph is extreme on the electronics especially temperature. I understand the torque difference but if your at full throttle the whole time they should be both pretty close to full torque but the 6s is pulling a 3rd less amperage giving less sag and keeping the electronics cooler and more stable. But for every day freestyle and racing it would be preference. The emax 2306 2750kv motors on 4s where pulling 55amps each and unsoldering the wires even with a high dead time. Side note, I believe prop manufacturers should be putting max design rpm and best effective rpm on there packaging since we can do rpm filtering now.
@@wodifpv644 for all out speed it's mostly aero. The top speed guy does like 180mph on 5S and ~215mph on 6s. It takes a balance of many many things to get there but mostly aero.
Yes this explains a lot for me, I just got some 5S packs on my ~2500kv motors, and yes I felt like I had to increase the motor output limit to get it to feel "fun", but then after a couple days of flying the 5S I put a 4S back on the every thing just felt snappier.
In regards to input voltage and P&D Gains regarding oscillation, this is very much a relative authority type problem, particularly in terms of how quickly the D-term oscillations with the inherent phase delay end up passing through there, which is why heavily filtering D-Term can be a useful partial solution, why DMin is actually useful despite the limitations, and mostly why changing the gains lower in excessively high KV setups matters. This interacts with PWM frequency and timing to a limited degree, as well as Rampup/Startup power (Again, Ryan Harrell would be the authoratative resources on this).
6s has torque because the electrical losses in the system are proportional to the current squared. The limit of a motor is temperature (apart from stresses in the bearings and other mechanical limits...) increasing the voltage allows you to decrease the current inversely proportionally... But the heat drops exponentially. You can therefore use wayyyy thinner wire and have wayyy more windings. Higher voltage has more torque because for the same volume of motor you can decrease the wire, increase the windings and magnetic field strength increases dramatically even though the current dropped! You're right about the batteries... But higher v lower kv for sure has more torque and/or for the same mechanical power runs more efficiently.
This has not been what testing has found. It's pretty clear that higher voltage has more peak torque because the whole system is higher wattage but lower average torque. It's also not more efficient. It's in fact a bit less efficient. The main savings do come from thinner wire but not in the stator. From my understanding you need to have the appropriate winds and volume of wire to generate the field. More winds that are thinner are not particularly better or worse. The savings comes from the rest of the system being able to be smaller but in this industry we don't make anything smaller so there are no efficiency savings for us. There are also increased switching losses in the FETs too. Larger capacity is what gives more flight time as long as the battery isn't being over stressed. Losses from heat are also similar because once all said and done, the current is sky high on 6s too at max. It's lower at lower throttles....which is why the whole torque curve is shifted
@@Kabab it feels to me like a lot of 6s setups are not meant to perform almost exactly the same as a 4s counterpart (btw im new to drones like I said... My experience comes from heli flying which I have been doing for before smartphones) people use the extra available power to just... Go faster and harder... Would you agree that for a given setup that has motors that are not terribly inefficient at hover for some reason, a comparable 4s setup will always fly less long than a 6s setup given equal total weight and total battery weight/watt hour?
@@tijssens as long as the 4s batt isn't being overstressed, it will fly for notably longer than an equivalent 6s.....for a few reasons. One of which being torque recreation and the other being ESC switching
@@Kabab wow... That is entirely the opposite of what is considered common knowledge in electric helis (which of course might mean that more people have it wrong including me :)) maybe the fact that collective pitch aircraft fly at at least 80%throttle makes my statement hold true most of the time... But the fact that drones fly at silly low throttles might explain the discrepancy? I'm intrigued to find out more about this... Really understand what is going on!
Hi, Do you think it would be a good idea to get the 6s version of the nazgul 5 hd but fly it on 4s as I'm a beginner or just go with the 4s version. From what I understand, 4s will work on the 1700kv motors but will be quite weak and mainly for cruising. Basically dilliberately making it weak so I can learn but future proofing it for when I go 6s.
here is a thought...maybe someone already discussed and means nothing but higher KV motors have less windings and lower resistance in the coils. I wonder if running 6s with higher kv motors and a motor limit will give more of the high current 4s feel roogi is talking about compared to running low KV 6s motors with 6s battery.
It doesn't. I left out a huge part of this discussion. I didn't say anything about insurance. Less winds is less resistance but higher inductance. Overall it takes more power to make the same final torque with higher kv/lower wind count. That's why low kv low volts is so efficient. Like 1800kv 4s is super efficient and 2500kv 4s is not as efficient.
I guess I need to make an actual video outlining the eletrochemical advantage, since it has been mentioned. I'll have to dig out my old electrochemistry stuff once I'm done with the paper I'm doing now, since others probably have questions on that.
I think you are wrong about the explanation of torque of motors. "Since the strength of the magnetic field is directly related to the current in the wire, the magnitude of the magnetic field would increase with an increase in voltage in the circuit." Thats simple physics: U=R*I U(Voltage) is higher R(Resistance) is the same I (Current) is less and because Escs are working with PWM, thats means the moment the motor is actually having current flowing through it (cause mosfet is powered), its "more current" in that very moment, but for less amount of time, therefore the average amount of Amps is less, even though the magnetic field is "stronger" in the moment the escs are delivering power. And the reason you have less torque in lower RPM range is, because the downtime of the motor being spinned is lets say 10%on 90%off, therefore, the motor spinning weaker (the same like driving the car in a higher gear) Hope its understandable.
You've contradicted yourself at the end there. FETs modulate current, not volts. They're switching more at low rpm due to the high voltage.....less current at low rpm. Current is directly proportional to magnetic field generation in an electromagnet. Less current is less magnetic field is less torque. Voltage does add torque in a secondary roundabout way but only when needed....as in when the FETs are open which only happens at the top end of the rpm. End result is less average torque from higher voltage but more peak torque due to the volts being able to drive the current harder and the whole system being higher wattage.
I'm flying hyperlite 2122kv motors on 6S. Why would that be considered too high? It's a free style 6" floss with dal biblade 5040 props and it flies incredibly with tons of torque at what seems like every throttle point.
that's totally fine. There's nothing presented here that should really change anything you do or are doing. Just things to think about. I myself really really like 1900kv 6S a lot on 5"
Hey KababFPV, just regarding the board and the noise (electrical) motors make on 4S - I am using such board on 7" ultralight 6S. There is such a great noise from those motors that it destroyed my VTX haha.....but it could be fixed by adding multiple capacitors. Ive added like 4 1000uF 25V and its kinda OK now. This defeats the purpose because I am using the board to save some weight so I am saying this to maybe direct You to let manufacturers know to add more capacitors so we could also use these boards on bigger stuff :)
well I did leave out the whole inductance part which sort of continues to balance things but in the end, the ESC is just switching a LOT more at the lower RPM's so no matter what the current ramp is more drastic on higher voltage if all else is equal.
Hi Kabab, can you do a tuning tutorial how you set up your toothpicks and your babyteeth? I would love to see that and i believe that i am not the one who wants to see that. If you have time for it, i would really appreciate it.
If I'm looking to get a 5 inch drone mainly for cinematic, mid range, mountain surfing, is it better to get the 4S one or the 6S one and what if I run 4S batteries on the lower KV motors?
4s on low kv motors is actually fantastic but it's not quite the same level of sharp performance as the appropriate voltage on the same motor. Flight time is like twice as long however with the same overall watt hour battery. Overall, it's best to have a balanced performing craft rather than focusing on just voltage or capacity
@@Kabab Thanks and agree. Your video made me stick to 4s (the drone I'm looking to buy is 6S compatible anyway, I would just need to swap the motors so I can do that down the line if needed)
you're right about electromagnetic field and how current generate it however, in my mind, the starting purpose of using 6s is for reducing sag during racing .
Yes that's when you use it. When you're pushing the battery and it can't deliver. That's when you need more voltage. No point in 6S on a sub 200g build. There's no stress on anything at that low
Interesting, but are you sure that current has higher impact on magnetic field, then voltage? For example 10a 4s and 10a 6s generate the same value of magnetic field? or on 6s it will be more powerfull field? I was thinking its combination of both
Well it is both. 10A at 6S is a lot more watts than 4S at 10A. Like I said, voltage pushes amps harder but not until they're needed. So what happens is you get more power overall. You're not getting torque from the volts. You're getting more of everything and less torque at the lower end of things.
Thanks for taking time to explain this I feel better now I'm new to hobby and going with 4S build ,But I thought made a mistake by not going to 6s because it seems everybody was going with 6S you helped Thanks 👍🏻👍🏻
I still recommend building all 5" quads to 6s and then running lower voltages if desired. Specifically because lower volts on low kv motors is so darn easy to fly. But 4s is totally fine. More than fine. A light 4s quad feels nicer to fly than a heavier 6s quad.
More cells means lower amps less sack less mass in PCB tracing and kabels. A 1S Xclass would need exreem amps and a instead of a XT90 a "XT800" the quad wil be to heavy due to all the Cu , A few CU heavy bricks of ESC's 10oz and wide tracing To reduce power los more cells or lighter weight of the quad. its Obvious that smal craft do not need 6S as amps are far within reasanble amound even for a high power version on 2 to 3S So 2" on 6S is to much also difficult to find low KV 11xx motor. Less choice so aften a not good mach prop motor battery combination.
Except when it doesn't - more voltage usually means more total power draw can happen. The result is usually better flight feel, but you wind up carting around a little more battery to make up the power expenditure (but it flies so well).
It's less torque but the comparatively higher kv makes up for most of that. They're running much bigger batteries as well so they need even more comparative kv on it. 1250 6S is equivalent to 1875 nah 4S. Nobody runs that big of a 4S on 5" normally
@KababFPV Great video! But I'm at a weird position where I can only run 4s on on my 6s quad (1800kv) for now. I'd like to know your thoughts on that in terms of efficiency. Did I just lose the benefits of both sides, or is it an overall more efficient (but under powered) quad? I noticed I could fly past 7 minutes and my cells would land at around 3.5 and recover back to 3.7 after a while. If I wanted to retain a bit of that efficieny all while gaining just a tad more power, (as I noticed how my quad would hover at near half throttle) would 5s be best for my case? Again great video and explanation as always
Na this is just food for thought. Fun to think about. I love 4S on 1800kv too. I have a feeling it adds the amps in the right places to fill in the torque curve. Yeah it's overall less but it feels better to fly because there's more current action than volt action
Great info all the way through! You lost me a bit with the torque vs RPM curves though. I'm curious why you didn't mention that you need a higher amount of turns to create (approximately) the same magnetic field on 6S? More turns = lower Kv right?
This video could have gone on for hours. You're absolutely right though. The impedance of the turns definitely plays in here and is probably at least partly the reason why we don't need a whole lot more kv on 6s to mostly fix the odd flight feel...kinda
Really interesting video! I've been wondering a lot about cell and voltage combinations recently for a build, I'd be curious to know what you recommend. I'm waiting on some Hyperlite 2405-2722KV that I'm putting the HQProp Ummagawd 4Play (4.8x3.6x4). AUW will be just under 600g with a 160g lipo. I just wanted to try something different, maybe a grippy cruiser. Considering 4-blades = less top-end, after watching this I feel like higher voltage is pointless and should maybe even look at 3S higher mAh. For example a Pulse 3S 1800mAh vs a GNB 4S 1300mAh. Thoughts?
KababFPV good point. So maybe 4S vs 5S with throttle cut should be my focus. Thanks for the reply! Keep up the awesome content, you've got the best format as far as I'm concerned 🤘🏼
Actually technically wider should be better on higher voltage because it again shifts the torque down the throttle curve. But there's a lot more going on so it's hard to say anything for sure. Go with what you feel in the real world.
Found this on fpvcycle: "we don't recommend a 5" ultralight. It's just not worth it. We don't recommend using any motor smaller than a 2207 or 2305 for 5" props. You're just giving up control performance by going smaller." Soo... What would you recommend for running Insta360go and maybe participating in 5" races? I at least like the look of the PP5 and the carbon topplate. Looks like its easier to mount stuff and maybe more durable...
This isn't really an ultralight. It's 310g. An ultralight is something that's now being more and more defined by the 250g auw marker and sacrifices to make it lighter. This frame would actually be excellent for the insta 360 go but there's no specific mount position or not made for it yet.
BTW you better save me a couple fouride 5"s for naming it. ;) Interesting discussion not sure I totally agree, although I think you are pretty on point with regards to traditional 5" and up. Where I think this changes is when you get into the situation where the battery is literally the limiting factor in the entire build, eg micros, ultralights. Heavy 3" pilots running big 14xx/15xx motors have found this, going from 4s 650/850 to 6s 550/650 yielded a big jump in performance in most cases. Back when we run "heavy" 2.5" going from 3s 650 to 4s 450 again yielded big improvements in performance all round. When it comes to situations where you are chasing the smallest battery you can get away with going up in voltage tends to yield positive results. I belive the difference here is that because the power:wight is so high the motor torque is simply a negligable consideration. You'd be hard pressed to say that a 6s 1507 3" is less responsive than a 4s 1507 3" for example. I do think if you are chasing that ultralight dragon and trying to shrink your lipos, you need to go up in voltage. Maybe if your lipos have power to spare you can afford to drop it again.
On that 3", you've gone up in overall Wh on the battery by moving to 6s. You also get a lot more rpm on the motor which is probably what you're considering as 'more performance'. Ultimately it's whatever you feel in the real world. The concepts are never complete enough to explain everything. I'll have some Fouride frames on reserve but there are actually not many 5" ones coming. I misjudged how good the 5" would be
@@Kabab True apples to apples is often hard just due to availability of cells, I think the crux of it though is about how much spare power your battery has available. The more flight time you spend @ >20-30c the more sense increasing the voltage makes. I'll keep an eye out on the patreon for the frames.
I just got most the things for my first proper race build (btw I bought 2 caddx ants, arriving Friday hopefully) - I have 3 6s 1300s and so there's no going back - I want to finish the build within the next two or so weeks- For now I'll probably get some T-motor velox 1950kv (the kind that don't look like the cyber xings) unless there's something better around the $13-14 mark. I'm still undecided on the props - any recommendations? I have no idea what to use. In hindsight 5s probably is where I should have gone probably, except for the fact there aren't many choices in my price range when it comes to motors. I believe Chief and also Mewo use 5S.
Consider the rcinpower Bison if you have gotten the motors already. The Velox is bottom of the barrel quality. Still fine and works fine but very low. The bison is special for a few reasons but also has an 11mm bearing which is wicked! Still cheap
On a 6s, have you measured the ave. voltage at one of the esc wires to the motor to set the actual voltage being delivered to motor as you ramp up the speed? I don't know, but going to ck. Better yet I'll put it on a scope. My guess is the voltage for a 4s is not the 16 or so volts a motor just starting to spin, the speed of the pulses is the same 3s vs 4s to get motor spinning not voltage? I know you're talking 6s but I don't have a 6s.
@@Kabab +my point was given that we test with a 4s and 6s battery that weight the same they will both hover at a ave. voltage below a 4s or 6s top voltage. so if you were to throttle limit the 6s battery so it could not put out more then 16.8, 4s volts (ave. under load) at full throttle then the two batteries will, should behave the same. Yes, NO, why? The test you did with the 6s and 4s also does not make sense with the motor noise, unless something in the system can't take 6s or will no longer take 6s.
@@fpvkabo because we usually drop the kv, the two will perform similarly. The 6s battery will have an easier time with the amps because they're overall so much less and the voltage will be more stable. While I understand what your asking, these usually aren't useful tests in the real world because there is no way to assure all things are equal between two different setups. Motor kv, ESC's, battery....
Good explanation from dentist ;) I made first quad years ago after listening your video abt 2208 2000kv motors on 4s. I love to fly it sometimes even today. And I agree 4s ftw.
This makes so much sense. I've just switched in the last 2 months and I didnnotice when in lower throttle they feel softer, but at about 30% (for me) it picks back up and has the power i need. I was thinking it was the change in props, but now looks like its a product of both instances. Lower torque cus of 6s, and lower thrust from diff props. Got it. I was pissed after I got new motors and all to go to 6s
Newb question here... what happens if your rx is no telemetry and you bind it with telemetry? Would thay cause errors? I get alot of rx loss on my rx/tx
It's just telemetry to the controller and half the time the code in the Rx or the controller is broken so it doesn't even work when you do bind it with telemetry. It doesn't really matter. If you get Rx loss from the quad being close to the controller that's normal. Radio waves don't work when very nearby. If you're getting it at a distance, check that your antennas aren't slammed up against carbon or aren't bent up or cut up at the very ends. The ends are the important parts if you're using anything but crossfire. For Crossfire you need to have it isolated and away from the frame with a vertical orientation if possible for best signal.
While i do have plenty of 6s, my Skitzo Super Nova frame is on 4s with 2750kv motors and it has remained my favorite quad. I have not been able to duplicate it on a 6s rig.
I have the parts for a 6S 5 inch UL kwad coming in tomorrow so it'll be interesting. BH 2004 1950KV motors, Gemfan 5125, AUW under 250g. Will upload footage on my channel
@@Kabab Want to give you a quick update. My 6S 5 inch Ultralight is flying beautifully, no significant electrical noise issue. I don't think it's necessarily quicker than 4S given the lower KV (1950) but am liking the faster throttle response and less sag. Test flight footage: ruclips.net/video/LbKmPqfciVU/видео.html
Hey, Kabab! Things are pretty difficult in brazil rn and i want to invest on a radio that i'll stay with until it breaks. Should i wait more for something new that is coming or the radiomaster is enough? Thanks!
There's no radio out there that stands out as really any better than anything else. I'd recommend waiting even though I'm not totally sure what's coming. If you were to get one now, I'd recommend the Jumper T18 actually. It just feels better quality in the hand. They're extremely similar however.
This has my interest peaked in building a 5” 3s quad. Based on this video and the description on your website, as long as it stays decently light, 3s is something you actually recommend for the higher kv 2203? Also I flossed this morning😉
KababFPV thanks for the reply I think I’m going to try it! Do you plan to revise the power pick at some point? I think I’m going to build one out but looking at a few other options like the pyro ul5 frame
Wondering if you could do a video on PID tuning. Not long flight an explanation, but an explanation of each and how it effects the flight characteristics. What I mean is not do a quick “ this is how you do this” and then a long flight with not much going on.
my answer is NO! on planes and gliders, it's better and easy to understand why a machine is made for 2s, another is in 3s, also after 4s, 5s, 6s, 12s! and it is easier to understand why it is simply a question of mass / propellers, motors, size, in short, everything has a meaning and each of the aces batteries have a role to play on certain machines .. that's why for a light machine, you need a light battery, not one that doubles the weight model! .. in short, I'm not an engineer too!, but for me it's a simple problem of mass / power ..
@@Kabab I was thinking a bit on the question, and for little quads i understand, but for bigger quads, would not make sence to convert voltage to amps, so the battery don't have to work so hard so it lives longer? I don't know if it would work like i think. Usually it is not that easy :D
The motor jitters in 4s due to high rpm compare to the 3s and the design of the motors. Have you seen the video of the slow mo guys spinning a disk, at the very high rpm the disk wobbles. Like in some power tools like a grinder or circular saw, blades have rpm limits. I'm not saying the design of the motors are flawed it's just design for a specific application and i hope to get a set of those.
I have not experienced 6S yet. I do have some brand new Ovonics waiting for a my rebuilt Flossstyle. To me 4S is plenty for anything under 5in, and still feels just fine on a 5in too. I do plan to build a 7in LR quad and use 6S1P 18650 packs. High voltage makes more sense the bigger the props are.
Yeah this isn't original in any way. The only thing special about this more recent breed of quad is just how light and powerful everything has become. I'm running something that can probably do 150-160mph off a frikin whoop board. If someone told me I'd be doing that just a year ago I'd think they're nuts! :-)
RSGo Competition: rsgochampionship.com/
Disclaimer:
I am NOT an engineer. I DO NOT know everything. This video is presented to the best of my knowledge at this point in time. If I've made errors, please educate me instead of spitting hate. Thank you.
FPVCycle 2203: bit.ly/3i7QPuA
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Table of Contents:
►00:00 - Intro
►04:25 - Example of issues on higher voltage
►07:25 - Comparison of 4S vs 6S
►12:58 - Basic electromagnet overview
►14:45 - Moving from 4S to 6S, current drop
►17:29 - What voltage does to torque
►21:55 - When do you need more volts
▼Join my FB group for more discussion: Kabab FPV
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@KababFPV
Increasing current flowing through a wire, does increase electron flow, producing a stronger magnetic field. However, that assumes the exact same wire, with the same length.
A magnetic field is produced along the entire length of the wire. Therefore, a wire 1m in length, with 10A passing through it, would produce an equivalent overall magnetic field as a 2m wire with 5a passing through it.
As you go down in kv, the number of turns on each pole has to increase with all else being equal, increasing the length of the wire proportionally.
Additionally, the resistance of the wire does increase proportionally as you either lengthen it, or reduce the cross sectional area of the conductor, or both as is the case of a lower kv winding.
A lower kv winding will have a thinner (smaller conductor cross section), and longer wire, with more turns. This will produce a higher resistance per phase.
The higher or lower resistance will not directly effect the magnetic field, however will increase or decrease the amount of current that will flow for a given voltage.
Theoretically, If a 2306 motor, with 8 turns per pole, resulting in a 2700kv motor (this is actually the result I got on a 3b 2306 motor)
Then a theoretical 16 turn winding would result in somewhere around 1350kv winding.
This motor would require half the current to produce the same magnetic field as the first 2700kv motor.
Twice the number of turns, with twice the length of wire.
There are a few problems with this scenario I can see though. Kv does not scale linearly with the nr of turns, as well as other practical implications. eg. when you increase the number of turns, the turns are wound over the initial ones, placing the copper further from the core, and the magnetic field becomes less effective.
Perhaps Ryan Harrelll could give us some insight on this?
@@darrensmith8107 i couldnt describe it better :) 👍
Excellent thoughts Darren. It gets more complicated with skin effects, particularly as they relate to near-saturation states as winding count and actual flux gets interesting at that point, which is why the lower KV from higher turn count doesn't just jump higher.
For the very limited scope of the concept that you were trying to convey, your presentation was dead-on simple physics. The movement of electrons in a conductor (a current) creates a magnetic field. If you curl the wire multiple times around a cylinder made of a ferromagnetic material (a nail) it will produce a magnetic field stronger than it would be if the material were not there. You can prove this quite easily by wrapping wire around a nail, preferably a thick one, but that’s not even a requirement. A regular 8 or 10 penny nail will participate even if the wire is wrapped quite haphazardly around it. You can amuse yourself (and your friends) by hooking it up to an old-style dry cell and picking up small metallic items quite readily. If you wrap more wire around the nail (or increase the current) you can pick up even larger things. Your explanation as I understood it, was simply to convey the concept that electricity flowing through a wire, around a magnetic form (regardless of the shape) or not, which varies in the amount of current flow from moment to moment will create a magnetic field which varies in strength with respect to the current flow. This is what an ESC does; it modulates the current flow in the magnetic coils of a motor, in response to signals from the Flight Controller, to make the motor turn faster or slower as a result. Because it is able to do this at incredible speed, the motors can be made to respond to very slight changes coming from the flight controller of varying amounts for each of the 4 motors in a quadcopter simultaneously . Without our ability to produce the complex hardware to do this, we would not be able to fly our craft the way we do. Yes, there are amazing engineering challenges to making this happen, but the concept remains simple without any need to get inductance effects, much less eddy currents or skin effects. Like I said the first time...you did great!
Thanks man. Your videos are making me smarter :D
I'm an engineer and im trying to ELI5 for your readers. The problem is motor inductance. There must be a equilibrium between motor inductance and voltage/current. Low inductance (=high kv, small size) have too fast response to the voltage steps provided by the esc, and the current is erratic and difficult to control, and might even reverse during a commutation cycle.
From what little I understand, this is currently managed by a faster processing to keep up with the switching better. But yeah that's the issue with high kv high power and I suspect is part of why I'm having issues with the quad in the video....which is why 3S is fine on it.
Having played with COMSOL, this really shakes out to switching related EMI bleedover, not necessarily any wobbles. Higher PWM frequency, reduced rampup power deltas, and then the actual motor inductance/capacitance, but they tend to be fairly lossy in that regard (a good thing), but this is why the excessively high KV setups see worse EMI, particularly when at the top end extremes, or when fed any amplifying oscillations.
"Infinite current and zero volts"
Take care there, Bob! You almost created a blackhole there! 😬
Now, exclusively at FPV Cycle a new flexible scale toothpick quad "The Singularity"! Bob R caption: "I do not claim to have invented the toothpick quad, but I may well end them as we know it"
@@jpslayermayor9293 😂😂😂😂
The Singularity awaits!
🙈
@@jpslayermayor9293 🤣🤣
KabaFPV, I think you missed a little point in the magnetic field explanation.
Yes, field is proportional to current, but ALSO to the number of windings.
The KV number is inversely proportional to the Inductance of the winding, which in turn is dependant on the number of windings (I think proportional to N²).
6s means lower KV, which means more turns, which means less current for the same field strength but more resistance, which is where the higher voltage comes into play to theoretically balance it.
I think the reason why it doesn't balance itself is, that field strenght is proportional to N, while inductance is to N².
Would be cool if someone checked that, who's better at math than me...
That would make sense.
I know this through many discussions and a few others have pointed it out as well. I believe this is at least in part why we don't need a whole lot more kv to adjust 6s into feeling better but I don't know by how much. I choose to leave this out because I don't know how much effect it has. Just choose to keep it as basic as I could which I know is not the whole story but the more I learn the more I know I don't know anything....will I ever know what's actually going on 🤷🏻♂️
@@Kabab "...will I ever know what's actually going on" Probably not, we cant even fit gravity into the standard model of quantum physics. Its going to be a while.
@@michaelwilkes0 as an electrical engineer, glad that somebody pointed that out :D thx
as an electrical engineer, glad that somebody pointed that out :D thx
We will always support fpvcycle ❤️
This was some solid nerd-core drone shit. Thx! Lovin’ my Babytooth
im not an engineer but i did stay at a holiday inn last night
? 🤔
It's an old reference, but it checks out.
@@friendlynomad9840 ruclips.net/video/eHCTaUFXpP8/видео.html
Flip FPV thanks!
Thank you for pushing our hobby forwards sir. We need more people like you out there.
That explain why most people prefer 2207 on 4S and 2306 on 6S too. Very interesting video, thanks for taking the time to explain to us plebs with simple words !
Yes the wider motors shift the torque curve down again. But not as much as voltage shifts it up.....this is the premises I'm working on for a new motor....didn't want to give away too much.
You're videos are always really interesting and informative, but they also make me question every purchase I've ever made in FPV sometimes :D
👏that's exactly the point. Fun to think about and might be helpful
Somehow I watched the whole vid and was interested the whole vid but didn’t understand half of it lmao. Still very interesting 🤔
Yep, same
🙈. Keep doing what you're doing. That's all.
@@Kabab so bro, does it mean if I use 4s on those fpvcycle 2203, would it always make sound? Please do reply.
@@AfafPrinceOSH you mean electionic noise by sound? If you take care to manage the noise then it will work great.
@@Kabab I mean as u used the 4s on it, it was making noise. Will it always make that noise? Or is it due to noise in gyro which in result is causing the noise in the motor?
Honestly, Bob, that's precisely why I didn't go to 6s. And I won't, at all. It makes no sense, exactly because of the current.
I tried to explain this back then when people were debating 4s vs 6s, but nobody would listen. 😕
I remember I commend in a video, maybe it was on your channel, I really don't remember, and a lot of people come to say I was wrong without any argument. So... I shut up.
BTW, I really hope it doesn't happen here again. I don't have any patience for debating on the internet anymore. 😕
Anyway, stay safe there! 🖖😊
You're wrong.....lol
Grow up .
LOL THATS WHAT the interwebs are for faceless in fighting .....ya moron
Interesting info here, thanks Kabab.
I started on (edit:1500mah) 4S, 2207 2500kv. I was always in a rush to build a 6S rig because of all the videos claiming longer flight times, less sag etc. When I finally built up my 2306.5 1850kv, on 1100mah 6S I was actually getting SHORTER flight times (Both at about 625g with Session5). I also found it's harder to find good performing, lightweight 6S batteries. My $46 Thunderpower 1100mah battery flies like a dream and is lightweight, but my $28 1000mah GNB is super heavy, and gives me short flights with sag comparable to 4S.
I've found the 1250mah 5S from pyro is one of the lightest packs that gives me 5+ minutes of freestyle flight, minimal sag, and I fly it on a 88% motor output limit on the 2207 2500kv. That is my go to for the "4S" quad. It seems I just have to cough up some more cash for the good batteries to get comparable performance on my 6S build.
Your experience is not unique unfortunately. The people claiming so much more flight time are using batteries that are way bigger than the equivalent 4s so of course it's going to have more flight time. But overall, 6s is actually less efficient.....but better voltage stability and improved electrochemistry condition.
im so glad your learning and figuring all this shit out and explaining it so it makes sense to me at least. thanks Bob!
Balance. It’s the key to everything in the universe:)
Just for historical perspective. Years ago, we used to run wimpy Gemfan 5030 bi blade props. Then everyone got excited about heavy bull nose props, then tri blades, etc. Ppl were trying to get more thrust by just beefing up the props, and not thinking about the efficiency of the motors. So motors and voltage isn't the whole story. Lots of guys kept everything the same and just started flying heavier, more aggressive and less efficient props (also just cause those props were more durable). I think prop tech is just as important as everything else in these equations. Do you want to punch out to the moon and kill your battery in 20 seconds, or do you want to fly smoothly for 3 minutes with consistent power, and your props are much more fragile. But material science has also come a long way. I remember flying Gemfam 2 blade 5030s that would all completely explode on a rough landing. Props are a big part of this story
It really does for 5in and up. If I’m being honest I have not flown any of my 4S quads in about 6months. It’s subtle but there is a real difference
why does kabab say that 6s feels worse and is less linear? When everyone I know who flies 4s and 6s freestyle says 6s feels better and is faster and lasts longer
@@cinialvespow1054 It depends on how you fly I guess. I can see how someone who flies aggressive freestyle with fast punch outs would benefit from 6s more as you get less sag and also higher peak rpm considering how we usually run higher kv motors for 6s than 4s equivalent. However for someone who prefers mellow freestyle and maybe slower proximity flying, more linear power delivery on 4s might be an advantage over 6s. That's just how I see it.
I built 5s and 6s quads, I really do fly my 5s quads more often since they are more controllable and easily tuned. I have tuned one to where you could barely hear the props in flight. That quad dose fly 7 to 11 mins without a GoPro with 1050 5s. I do give the battery time to recover in flight if I do flip flops, or race style flights. I wish Betaflight would have 1 Gauge for RPM like how regular vehicles have the RPM gauge from 1 to 9. But I do enjoy you’re videos. Can’t wait to see whats next ✌🏼
I'm not sure how you would display rpm in a meaningful way since all 4 motors spend most of a flight at differing rpms.
Really what you're after is a strain gauge to indicate how many Amperes the craft is drawing out of the maximum.
This would be difficult to reasonably calibrate, but we could get close with the following example:
Say at *16.0V* your quad pulls *100A* & at *13.6V* it pulls *85A* .We create a linear scale using these points, then measure instantaneous voltage and current then compare it to the scale.
Your quad is cruising at *18A* , battery voltage is reading at *14.8V* .
*14.8V* is *50%* along your voltage scale, meaning we can estimate max amps to be exactly between *100A* + *85A*, or *92.5A* .
We take your cruising current of *18A* and divide it be the _theoretical max_ of *92.5A* and that gives us a "strain" _estimation_ (more on this below) of *~19.5%*
Your "RPM" gauge of 1-9 would then show *1.75 "revs"* if you count *0* as the lowest or *2.5 "revs"* if *1* was the lowest.
Now, _why an estimation_ you ask? Because this scale would sadly not be linear - the LiPo chemistry doesn't work like that; Supplying 20A is *MORE than twice* the work for a battery than 10A and the battery will output less useable power overall. This only gets worse the more Amperes you draw. Again, we could make some simple observations and apply a rough fudge-factor to approximate this, but getting it to any reasonable degree of accuracy would require testing and calibration for each individual battery throughout it's lifespan due to the ever-increasing internal resistance.
On the other more simple side, you can also display the current throttle stick position on the OSD. This is *not* equivalent to an "RPM" gauge, in car terms that would show how far the accelerator was depressed. It would simply show the *requested* power not the _actual_ power.
Hope this helps give you some stuff to consider in your quest for an OSD rev gauge :)
@@JustInvertedFpv with bidirectional Dshot you can actually show all 4 individual motor speeds on the OSD. I'm not entirely sure why you'd want that but it's doable :D
I'm Not an engineer, but I play one on TV. LOL. The erratic movement you are seeing in the motors is the same thing I see anytime I run a quad with props off. It is only more amplified to the naked eye as you increase voltage, giving the PID more authority. The default PID's on most firmware is set to expect the resistance of the props. You could stabilize the erratic behavior of the motors by dropping P gains in the software, but then the quad would not fly very well with props on. Run the same test, outside, away from you, with props on at idle. I think you will find that the default PID's are very stable when they are run with the load they are designed for. The PID Loop is trying to reach a goal over time (RPM or Axis angle of the quad) as set by the software. Example is, If the PID Loop is set to try a certain amount to reach it's goal within a certain time with props on, when you take the props off, it will get there too fast and have to slam on the brakes because it will "overshoot" the target. Because it can't learn on it's own that it is doing this, it will do it over and over again, causing erratic behavior. Let's say you added really heavy props or props with an aggressive pitch. The motors would be more stable but very sluggish until you command the PID's to try harder to reach that goal.
The key I have found through people way more experienced in this is than I am is,
Match your max prop RPM's in your 6s build as close as you can to max RPM in your 4s build.
4s is 4.2 volts x 4 series cells right? so 16.8 volts fully charged. With a 2450kv motor, we are looking at a max RPM of 2450rpm x 16.8volts. So 41,160 RPM.
Now Lets build a 6s quad that we intend to behave in almost the same way.
6s is 4.2 volts x 6 cells. So thats 25.2volts. Take the max Rpm from the 4s build and divide it by the voltage of 6s. So 41,160 divided by 25.2 is approx 1,633kv for the motor. I've never seen a 1,633 motor before so I would try to get close by getting a 1700kv motor. After making these changes to a 4s quad (Keep in mind that all electronics on the quad must be rated to run at 25.2 volts or above to keep from frying them) you should be able to run 6s on your 4s settings with very little adjustment needed because the max RPM is going to be about the same. The difference in the 6s build is that is is relying more on the voltage to spin up the motors than the capacity of the battery. On a 4s full throttle punch, the voltage drop is faster and then you are in the capacity area of the battery sooner. A 6s battery has higher voltage and more cells to sustain the load so voltage drop is more preventable. We don't stay in full throttle very long but some of us just want a little more than we get out of 4s and 6s seems to provide that. Some have said that moving to a 6s setup gives much longer flight times as well due to battery having better voltage "bounceback" or recovery after a throttle punch. I have noticed this myself and really enjoy the benefits.
That's my 2 cents. Be safe and responsible out there guys. Don't get the rest of us in trouble by flying like a moron!
Thanks.
LOL. I should have waited until my internet connection came back and I could watch the rest of the video before commenting. Awesome video KABAB! Thank's for your contributions to the hobby sir!
The problem with the quad has nothing to do with any of that. 😁. It was purely where the cap was positioned. Just had to move it closer to the board.
Very informative video, thank you! I noticed that Gemfan gives (very) similar information on 5125 prop at Banggood. Just one thing, you didn't mention the different amount of coil turns that different kv motors have. If I'm not mistaken more turns (found in lower kv motors) can make an electromagnet stronger. Please correct me if I'm wrong and again thanks for the video!
Yes and no. More turns means less current is needed to create the field but you need more current to saturate the stator. Less turns will have faster moving current....it's ultimately about the same but the difference with higher kv is that the field strength rate of change is faster because it ramps up faster.
Thanks for the heads (rsgo competition). The prizes look really good, definitely need to go through all my rsgo footage and make an entry.
Reminds me of the argument, do you need an amplifier to use with your headphones? And then the trend and technologies evolved to remove the headphone jacks...
Cell phone Mini head set Amp sitting on my shelf next to my desk .. Thinking about adding it to the desktop workstation and seeing if it blows my puter speakers
I personally fly 4s. Have never tried 6s, ive just never found a reason to go 6s. At first i was thinking to switch once i broke a motor, my BrotherHobby motors havent broken in 15months, so im going to stay hsha. I am very happy with the performance, i get 5-6 minutes of mixed flight with a satisfying amount of top speed. There is a slight sag at the very emd of the battery but i am a casual freestyler so i dont mind 👍
I honestly was experimenting with low KV longer flight time maybe 6" arms and 6" props but I'm seeing no diff yet Ironically I was just about to order a bloat of 6S batteries .. LOL
Definitely on to something here. Shawn Ames is doing something interesting with his Freedom Spec race, coming up on the fourth. But the most interesting thing being that battery is set as 3S.
This is one of the most interesting discussions I've watched from you. I don't know why. Until now, I've really never understood why using equivalent kV to 4S on 6S doesn't work well. Great video!
This is fascinating. I wonder if you can use a regulator to limit the voltage and then "shift gears" to a higher voltage to help provide the most torque possible. Obviously the biggest issue with this is the kv would then have to be variable as well. Honestly I don't understand how kv is implemented into the construction of the motor. Is it the coil amount? The gage of wire? Magnet size? I actually don't know. But I fear it can't be variable which could destroy my "gear shifting" idea.
I'm working on that to better be able to spin it into English people can understand.
Equivalent 6s to 4S motors are same speed but it's the total WATTS output power that counts. A 6s setup will run cooler and more efficient at same speed to 4s. It's at about volts X amps
That these gyros meant for phones (very optimized current draw), that work by very precisely vibrating a nano scale mass, and then very precisely measuring the difference that's crated by moving moving it. That this still works when the gyro is on the same PDB as 4 extremely tightly packed, creatively component reduced ESCs, is kinda ridiculous.
The magnetic field strength is proportional to Ampere*turns, not current-only. Force/torque is proportional to the field.
A 1000kv motor needs twice the number of turns on a stator pole compared to a 2000kv motor with the same construction. Thus, 20 Amps through the 2000kv motor produces as much torque as 10 Amps through the 1000kv motor.
There is a catch though. Winding inductance, and therefore the ability to change current/motor torque quickly, increases with number of turns squared. A single stator winding on that 1000kv motor therefore has four times the inductance of the winding in the 2000kv motor case. But current must ramp to half of it to produce the same amount of torque. So it is 4/2 = twice as 'sluggy' as the 2000kv motor. Maybe that is the reason why we prefer higher kv on 6S?
Bingo
Very very helpful. Totally forgot about that but makes total sense. So it's probably a combination of them which is why we don't need a whole lot more kv. Just a bit more to make it feel closer to 'right'
You've got that a bit backwards mate - the 1000kV motor would have more turns compared to the 2000kV motor not the other way around.
@@Imakilln : Yes, you are right, I swapped them around. I will edit my text.
Forever wondering how you can fly a 5in with a AIO board and my toothpicks go up in flames after like 3 packs on 3s
🙈 that's the definition of this hobby. 🔥🔥🔥🔥 We're basically pyromaniacs
Yes yes yes! More / longer videos please;)). non of my quads are flying so im really enjoying these videos. Thanks!!!
Would you recommend buying a GoPro hero 5 session today at $100 or going for another camera?
A refurbished session 5 is easily the very best camera you can find for the money.
If you can get a Session 5 for $100 USD, buy it. You could always sell it and make a profit if anything.
for the price the hero 5 or 5 session is the best buy. if you can find a session 5. ive got a hero 5 i just bought ill sell for $100.
Jesus man $100 usd is a steal haha... costs £145+ = $180 in the uk
@@Kabab Do you think there will be a GoPro 9 session?
The issues you explain going from higher s to 3s to me seem to come from the higher gain in the feedback loop. Your pid settings are the same... But the motor response increases the mechanical gain in the loop because the motors have more torque which has to be compensated for in the software pid. Lowering the total gain will probably solve it. I'm an engineer :) but really new to betaflight and drones in general so I might also be entirely wrong :)
In the case of this particular quad what I believe is happening is entirely noise in the system and the increased voltage is just exaggerating it. Never mind the quad. I was just using it to show how things can suck on higher voltage. Nothing more. I'll fix tht noise issue on the quad.
Looking forward to more videos like this. Thanks Bob, love all the info.
Offer still stands on being able to help with capital allocation. Keep the awesomeness coming.
Thank you very much but we're trying to make this work without raising money. margins are so darn slim it would mean we'd be working for someone else for zero pay.
Great video. Amps kill if relatively little voltage is present. Volts with relatively no Amps just make you flop like a fish (taser) or make your hair stand on end (electrostatic generator). The right combination of the two is what make the lights come on (Watts). I relate electricity to fluid mechanics in that Voltage is a pump or vessel of stored energy. The size of the vessel is its capacity(mAH). Amps is the size of the pump lines or how fast that energy can flow. There is of course resistance (Ohms) which affects the flow of that current. The difference between fluids and electricity is fluid is not compressible. If you want more pressure you need a bigger pump. Voltage however, through a capacitor, is compressible. That is why Quads need a Cap to meet the high current demand and minimize voltage sag. The marriage of volts to amps is as equally important as props to motors. Long track racers need the top end while the short tracks would need the quickness off the line and between the gates. This same discussion can apply to Inline 6 vs V8 engines. The I6 is insanely quick off the line but does not have the torque or HP of the V8. I think the long and short of it is: what is the weight/size of the Quad, what do you want it to do with it, and how long do you need to do it. That would be an interesting video. Compare size/weight class with different battery/motor/prop combos on both long and short tracks. Thanks for your work.
High voltage is being used because for the same amount of power you need less current. That results in smaller ESCs and cables needed making the quad lighter and cheaper.
Except that the ESC is actually larger as heavier. We don't go smaller and lighter typically when we get more potential wattage output. We just use the wattage to go faster....this is performance flying. Not dhi float around flying
Great video. Thank you Kabab for sharing your learning and experience. You may have just solved a problem I'm currently facing. Been trying to get motors designed for 4S to work with 5S, and likely pushing the motors too hard as a result.
You forgot one thing! A higher number is better! 6 is 150% of 4, so it just HAS TO BE 150% better. Go away with all your fancy "maths" and "experience".
Just kidding of course. Love the video, very interesting
Thank you for this well explained and logical journey to explain your thinking. I learnt lots and also forms a base to help make build decisions going forward! Look forward to the continuation of your research👍🏻 great stuff..love how this hobby makes your your head spin when youre flying and when youre not!
I love the look of your motors! I’ll hopefully be able to get some soon
Every time i watch your video's you make me wanna brush my teeth
WOOOOO!!!!
@@Kabab dentist man
Again a really informative video ! keep going
Another thing that 6s over 4s is because of the lower temperature from lower amperage the electronics run smoother. When I was doing my run to hit 145mph back in spring of 2017 my main issue was melting motors and soldering joints. Switched to higher rated connectors then to 6s to lower the temperature of the electronics and the solder joints. APC and the other prop companies at that time all told me that they design the top speed of there props to be 25000rpm +/-1000 max. The props start loosing efficacy and the ability to hold there shape. I was running 2306 2750kv on 6s to hit 145mph.
Well yes but if you wanna get tht torque back then you need higher kv which drives the current and because you have higher kv and more voltage you get more rpm which draws more current....so as long as you keep it lowish on the throttle it's less heat.
@@Kabab true but for all out speed runs which are 100% throttle aerodynamics and temperature are most of the issues i have. 145mph is extreme on the electronics especially temperature. I understand the torque difference but if your at full throttle the whole time they should be both pretty close to full torque but the 6s is pulling a 3rd less amperage giving less sag and keeping the electronics cooler and more stable. But for every day freestyle and racing it would be preference. The emax 2306 2750kv motors on 4s where pulling 55amps each and unsoldering the wires even with a high dead time. Side note, I believe prop manufacturers should be putting max design rpm and best effective rpm on there packaging since we can do rpm filtering now.
@@wodifpv644 for all out speed it's mostly aero. The top speed guy does like 180mph on 5S and ~215mph on 6s. It takes a balance of many many things to get there but mostly aero.
Yes this explains a lot for me, I just got some 5S packs on my ~2500kv motors, and yes I felt like I had to increase the motor output limit to get it to feel "fun", but then after a couple days of flying the 5S I put a 4S back on the every thing just felt snappier.
In regards to input voltage and P&D Gains regarding oscillation, this is very much a relative authority type problem, particularly in terms of how quickly the D-term oscillations with the inherent phase delay end up passing through there, which is why heavily filtering D-Term can be a useful partial solution, why DMin is actually useful despite the limitations, and mostly why changing the gains lower in excessively high KV setups matters.
This interacts with PWM frequency and timing to a limited degree, as well as Rampup/Startup power (Again, Ryan Harrell would be the authoratative resources on this).
6s has torque because the electrical losses in the system are proportional to the current squared. The limit of a motor is temperature (apart from stresses in the bearings and other mechanical limits...) increasing the voltage allows you to decrease the current inversely proportionally... But the heat drops exponentially. You can therefore use wayyyy thinner wire and have wayyy more windings. Higher voltage has more torque because for the same volume of motor you can decrease the wire, increase the windings and magnetic field strength increases dramatically even though the current dropped! You're right about the batteries... But higher v lower kv for sure has more torque and/or for the same mechanical power runs more efficiently.
This has not been what testing has found. It's pretty clear that higher voltage has more peak torque because the whole system is higher wattage but lower average torque. It's also not more efficient. It's in fact a bit less efficient. The main savings do come from thinner wire but not in the stator. From my understanding you need to have the appropriate winds and volume of wire to generate the field. More winds that are thinner are not particularly better or worse. The savings comes from the rest of the system being able to be smaller but in this industry we don't make anything smaller so there are no efficiency savings for us. There are also increased switching losses in the FETs too. Larger capacity is what gives more flight time as long as the battery isn't being over stressed.
Losses from heat are also similar because once all said and done, the current is sky high on 6s too at max. It's lower at lower throttles....which is why the whole torque curve is shifted
@@Kabab it feels to me like a lot of 6s setups are not meant to perform almost exactly the same as a 4s counterpart (btw im new to drones like I said... My experience comes from heli flying which I have been doing for before smartphones) people use the extra available power to just... Go faster and harder... Would you agree that for a given setup that has motors that are not terribly inefficient at hover for some reason, a comparable 4s setup will always fly less long than a 6s setup given equal total weight and total battery weight/watt hour?
@@tijssens as long as the 4s batt isn't being overstressed, it will fly for notably longer than an equivalent 6s.....for a few reasons. One of which being torque recreation and the other being ESC switching
@@Kabab wow... That is entirely the opposite of what is considered common knowledge in electric helis (which of course might mean that more people have it wrong including me :)) maybe the fact that collective pitch aircraft fly at at least 80%throttle makes my statement hold true most of the time... But the fact that drones fly at silly low throttles might explain the discrepancy? I'm intrigued to find out more about this... Really understand what is going on!
I did a test, hovering same quad on 6S and 4S same weight, 6S was drawing 66% of current of 4S
But the performance of the calculated correct 6s kv is much worse
Great content, I learn so much from your videos.
Wow. This video is soo good :D Thanks for that. I learned so much.
I know this isn't the most recent video, but would lowering the ramp-up power help with the twitchiness on 4s?
Yes absolutely
Hi, Do you think it would be a good idea to get the 6s version of the nazgul 5 hd but fly it on 4s as I'm a beginner or just go with the 4s version. From what I understand, 4s will work on the 1700kv motors but will be quite weak and mainly for cruising. Basically dilliberately making it weak so I can learn but future proofing it for when I go 6s.
Yeah that's a good option. I'd generally cautioun any rtf. It'll most definitely break and you'll need to repair it
tbh i did think that frame looked ugly, but only when it was naked. With all the components on it, it looks kinda cool
The top is still hideous 🙈
Filters all the way to the left can send a quad to the moon, using that as a comparison point is just nonsense.
It just happened to be an issue that happened right before I sat down to make the video so I just threw it in.
Reduce P 25%, and 4s will be as smooth as 3s.
@@cedricgrandseigne Closer to by 33% (it gets odd), but yeah that's the idea.
Eating steak right now and I'm so gonna floss after this...
here is a thought...maybe someone already discussed and means nothing but higher KV motors have less windings and lower resistance in the coils. I wonder if running 6s with higher kv motors and a motor limit will give more of the high current 4s feel roogi is talking about compared to running low KV 6s motors with 6s battery.
It doesn't. I left out a huge part of this discussion. I didn't say anything about insurance. Less winds is less resistance but higher inductance. Overall it takes more power to make the same final torque with higher kv/lower wind count. That's why low kv low volts is so efficient. Like 1800kv 4s is super efficient and 2500kv 4s is not as efficient.
I guess I need to make an actual video outlining the eletrochemical advantage, since it has been mentioned. I'll have to dig out my old electrochemistry stuff once I'm done with the paper I'm doing now, since others probably have questions on that.
yes! Do that!
@@Kabab Yup, I totally get that, and I figure I'm not the only person willing to underwrite for early access and design input.
I think you are wrong about the explanation of torque of motors.
"Since the strength of the magnetic field is directly related to the current in the wire, the magnitude of the magnetic field would increase with an increase in voltage in the circuit."
Thats simple physics:
U=R*I
U(Voltage) is higher
R(Resistance) is the same
I (Current) is less
and because Escs are working with PWM, thats means the moment the motor is actually having current flowing through it (cause mosfet is powered), its "more current" in that very moment, but for less amount of time, therefore the average amount of Amps is less, even though the magnetic field is "stronger" in the moment the escs are delivering power.
And the reason you have less torque in lower RPM range is, because the downtime of the motor being spinned is lets say 10%on 90%off, therefore, the motor spinning weaker (the same like driving the car in a higher gear)
Hope its understandable.
You've contradicted yourself at the end there. FETs modulate current, not volts. They're switching more at low rpm due to the high voltage.....less current at low rpm. Current is directly proportional to magnetic field generation in an electromagnet. Less current is less magnetic field is less torque. Voltage does add torque in a secondary roundabout way but only when needed....as in when the FETs are open which only happens at the top end of the rpm. End result is less average torque from higher voltage but more peak torque due to the volts being able to drive the current harder and the whole system being higher wattage.
I'm flying hyperlite 2122kv motors on 6S. Why would that be considered too high? It's a free style 6" floss with dal biblade 5040 props and it flies incredibly with tons of torque at what seems like every throttle point.
that's totally fine. There's nothing presented here that should really change anything you do or are doing. Just things to think about. I myself really really like 1900kv 6S a lot on 5"
Hey KababFPV, just regarding the board and the noise (electrical) motors make on 4S - I am using such board on 7" ultralight 6S. There is such a great noise from those motors that it destroyed my VTX haha.....but it could be fixed by adding multiple capacitors. Ive added like 4 1000uF 25V and its kinda OK now. This defeats the purpose because I am using the board to save some weight so I am saying this to maybe direct You to let manufacturers know to add more capacitors so we could also use these boards on bigger stuff :)
Great content and great presentation. I'm a physicist and you nailed it. Thanks for the video.
well I did leave out the whole inductance part which sort of continues to balance things but in the end, the ESC is just switching a LOT more at the lower RPM's so no matter what the current ramp is more drastic on higher voltage if all else is equal.
Hi Kabab, can you do a tuning tutorial how you set up your toothpicks and your babyteeth? I would love to see that and i believe that i am not the one who wants to see that. If you have time for it, i would really appreciate it.
These are the things that I haven't been able to make content around due to constantly sold out ! 🙈. Coming soon
If I'm looking to get a 5 inch drone mainly for cinematic, mid range, mountain surfing, is it better to get the 4S one or the 6S one and what if I run 4S batteries on the lower KV motors?
4s on low kv motors is actually fantastic but it's not quite the same level of sharp performance as the appropriate voltage on the same motor. Flight time is like twice as long however with the same overall watt hour battery. Overall, it's best to have a balanced performing craft rather than focusing on just voltage or capacity
@@Kabab Thanks and agree. Your video made me stick to 4s (the drone I'm looking to buy is 6S compatible anyway, I would just need to swap the motors so I can do that down the line if needed)
you're right about electromagnetic field and how current generate it however, in my mind, the starting purpose of using 6s is for reducing sag during racing .
Yes that's when you use it. When you're pushing the battery and it can't deliver. That's when you need more voltage. No point in 6S on a sub 200g build. There's no stress on anything at that low
Interesting, but are you sure that current has higher impact on magnetic field, then voltage? For example 10a 4s and 10a 6s generate the same value of magnetic field? or on 6s it will be more powerfull field? I was thinking its combination of both
Well it is both. 10A at 6S is a lot more watts than 4S at 10A. Like I said, voltage pushes amps harder but not until they're needed. So what happens is you get more power overall. You're not getting torque from the volts. You're getting more of everything and less torque at the lower end of things.
Bob...that doctor hand writing😂
Thanks for taking time to explain this I feel better now I'm new to hobby and going with 4S build ,But I thought made a mistake by not going to 6s because it seems everybody was going with 6S you helped Thanks 👍🏻👍🏻
4s is fine bro especially if ya dont carry that pig hero 7 or 8 every flight
I still recommend building all 5" quads to 6s and then running lower voltages if desired. Specifically because lower volts on low kv motors is so darn easy to fly. But 4s is totally fine. More than fine. A light 4s quad feels nicer to fly than a heavier 6s quad.
@@Kabab my stack&FC can handle it but I have 2345 KV motors will that work?
@@sully4875 yup just adust throttle % in BF ...n run a big cap
LIKE if you think Kabab should start a podcast
Basically you're spending the lower 2/3 of the throttle underpowered compared to 4s and playing catch up.
More cells means lower amps less sack less mass in PCB tracing and kabels.
A 1S Xclass would need exreem amps and a instead of a XT90 a "XT800" the quad wil be to heavy due to all the Cu , A few CU heavy bricks of ESC's 10oz and wide tracing
To reduce power los more cells or lighter weight of the quad.
its Obvious that smal craft do not need 6S as amps are far within reasanble amound even for a high power version on 2 to 3S So 2" on 6S is to much also difficult to find low KV 11xx motor. Less choice so aften a not good mach prop motor battery combination.
Except when it doesn't - more voltage usually means more total power draw can happen. The result is usually better flight feel, but you wind up carting around a little more battery to make up the power expenditure (but it flies so well).
How do you install betaflight 357? I need that for my mobula 6 but can only go back to 400
You can get it from the GitHub and do it manually. The BF devs are hell bent on making shit as hard as possible for everyone
Heideggar would be pleased. Nice congregation of applied concepts .
First time watching your whole video,I all ways change video first 10 sec,so good for y
So why did all freestylers switch to 6s if it has less torque? Longer flight times with 1250 mah?
It's less torque but the comparatively higher kv makes up for most of that. They're running much bigger batteries as well so they need even more comparative kv on it. 1250 6S is equivalent to 1875 nah 4S. Nobody runs that big of a 4S on 5" normally
@KababFPV Great video! But I'm at a weird position where I can only run 4s on on my 6s quad (1800kv) for now. I'd like to know your thoughts on that in terms of efficiency. Did I just lose the benefits of both sides, or is it an overall more efficient (but under powered) quad? I noticed I could fly past 7 minutes and my cells would land at around 3.5 and recover back to 3.7 after a while. If I wanted to retain a bit of that efficieny all while gaining just a tad more power, (as I noticed how my quad would hover at near half throttle) would 5s be best for my case? Again great video and explanation as always
Na this is just food for thought. Fun to think about. I love 4S on 1800kv too. I have a feeling it adds the amps in the right places to fill in the torque curve. Yeah it's overall less but it feels better to fly because there's more current action than volt action
@@Kabab It's good to know I'm not alone on the low kv 4s train haha. thanks for the input
This was brilliant I was on the verge of going 6s but I can't argue with science.
Great info all the way through! You lost me a bit with the torque vs RPM curves though. I'm curious why you didn't mention that you need a higher amount of turns to create (approximately) the same magnetic field on 6S? More turns = lower Kv right?
This video could have gone on for hours. You're absolutely right though. The impedance of the turns definitely plays in here and is probably at least partly the reason why we don't need a whole lot more kv on 6s to mostly fix the odd flight feel...kinda
Really interesting video! I've been wondering a lot about cell and voltage combinations recently for a build, I'd be curious to know what you recommend. I'm waiting on some Hyperlite 2405-2722KV that I'm putting the HQProp Ummagawd 4Play (4.8x3.6x4). AUW will be just under 600g with a 160g lipo. I just wanted to try something different, maybe a grippy cruiser. Considering 4-blades = less top-end, after watching this I feel like higher voltage is pointless and should maybe even look at 3S higher mAh. For example a Pulse 3S 1800mAh vs a GNB 4S 1300mAh. Thoughts?
Well more blades is more load which will pull more amps and sag batteries harder. So more volts is likely going to help
KababFPV good point. So maybe 4S vs 5S with throttle cut should be my focus. Thanks for the reply! Keep up the awesome content, you've got the best format as far as I'm concerned 🤘🏼
I have also noticed that i prefer 22XX motors to 23XX motors on 6s. Not sure why but i do.
Actually technically wider should be better on higher voltage because it again shifts the torque down the throttle curve. But there's a lot more going on so it's hard to say anything for sure. Go with what you feel in the real world.
@@Kabab I just started flying the hyperlite e series 2207.5 1722kv and they're hands down the best budget motor I've flown ( zing, rcx, dys, eco's)
Found this on fpvcycle:
"we don't recommend a 5" ultralight. It's just not worth it. We don't recommend using any motor smaller than a 2207 or 2305 for 5" props. You're just giving up control performance by going smaller."
Soo... What would you recommend for running Insta360go and maybe participating in 5" races? I at least like the look of the PP5 and the carbon topplate. Looks like its easier to mount stuff and maybe more durable...
This isn't really an ultralight. It's 310g. An ultralight is something that's now being more and more defined by the 250g auw marker and sacrifices to make it lighter.
This frame would actually be excellent for the insta 360 go but there's no specific mount position or not made for it yet.
BTW you better save me a couple fouride 5"s for naming it. ;)
Interesting discussion not sure I totally agree, although I think you are pretty on point with regards to traditional 5" and up. Where I think this changes is when you get into the situation where the battery is literally the limiting factor in the entire build, eg micros, ultralights.
Heavy 3" pilots running big 14xx/15xx motors have found this, going from 4s 650/850 to 6s 550/650 yielded a big jump in performance in most cases. Back when we run "heavy" 2.5" going from 3s 650 to 4s 450 again yielded big improvements in performance all round.
When it comes to situations where you are chasing the smallest battery you can get away with going up in voltage tends to yield positive results. I belive the difference here is that because the power:wight is so high the motor torque is simply a negligable consideration. You'd be hard pressed to say that a 6s 1507 3" is less responsive than a 4s 1507 3" for example.
I do think if you are chasing that ultralight dragon and trying to shrink your lipos, you need to go up in voltage. Maybe if your lipos have power to spare you can afford to drop it again.
On that 3", you've gone up in overall Wh on the battery by moving to 6s. You also get a lot more rpm on the motor which is probably what you're considering as 'more performance'. Ultimately it's whatever you feel in the real world. The concepts are never complete enough to explain everything. I'll have some Fouride frames on reserve but there are actually not many 5" ones coming. I misjudged how good the 5" would be
@@Kabab True apples to apples is often hard just due to availability of cells, I think the crux of it though is about how much spare power your battery has available. The more flight time you spend @ >20-30c the more sense increasing the voltage makes.
I'll keep an eye out on the patreon for the frames.
So maybe a slight adjustment to throttle curve on 6s setups would alleviate the torque/feel issue at lower and middle ranges?
it could help
I just got most the things for my first proper race build (btw I bought 2 caddx ants, arriving Friday hopefully) - I have 3 6s 1300s and so there's no going back - I want to finish the build within the next two or so weeks- For now I'll probably get some T-motor velox 1950kv (the kind that don't look like the cyber xings) unless there's something better around the $13-14 mark. I'm still undecided on the props - any recommendations? I have no idea what to use.
In hindsight 5s probably is where I should have gone probably, except for the fact there aren't many choices in my price range when it comes to motors. I believe Chief and also Mewo use 5S.
Consider the rcinpower Bison if you have gotten the motors already. The Velox is bottom of the barrel quality. Still fine and works fine but very low. The bison is special for a few reasons but also has an 11mm bearing which is wicked! Still cheap
On a 6s, have you measured the ave. voltage at one of the esc wires to the motor to set the actual voltage being delivered to motor as you ramp up the speed? I don't know, but going to ck. Better yet I'll put it on a scope. My guess is the voltage for a 4s is not the 16 or so volts a motor just starting to spin, the speed of the pulses is the same 3s vs 4s to get motor spinning not voltage? I know you're talking 6s but I don't have a 6s.
the average voltage of 6S is more consistent. That's the whole point of 6S
@@Kabab +my point was given that we test with a 4s and 6s battery that weight the same they will both hover at a ave. voltage below a 4s or 6s top voltage. so if you were to throttle limit the 6s battery so it could not put out more then 16.8, 4s volts (ave. under load) at full throttle then the two batteries will, should behave the same. Yes, NO, why? The test you did with the 6s and 4s also does not make sense with the motor noise, unless something in the system can't take 6s or will no longer take 6s.
@@fpvkabo because we usually drop the kv, the two will perform similarly. The 6s battery will have an easier time with the amps because they're overall so much less and the voltage will be more stable.
While I understand what your asking, these usually aren't useful tests in the real world because there is no way to assure all things are equal between two different setups. Motor kv, ESC's, battery....
Good explanation from dentist ;) I made first quad years ago after listening your video abt 2208 2000kv motors on 4s. I love to fly it sometimes even today. And I agree 4s ftw.
This makes so much sense. I've just switched in the last 2 months and I didnnotice when in lower throttle they feel softer, but at about 30% (for me) it picks back up and has the power i need. I was thinking it was the change in props, but now looks like its a product of both instances. Lower torque cus of 6s, and lower thrust from diff props. Got it. I was pissed after I got new motors and all to go to 6s
It is an unfortunate feel change. But if you need to fight sag, this is the only way that hammers it
I deff agree Bob. Love ur info and vids. Especially love my tp3 and my powerpicj stuff will be here fri so ill get a review together for ya
Newb question here... what happens if your rx is no telemetry and you bind it with telemetry? Would thay cause errors? I get alot of rx loss on my rx/tx
It's just telemetry to the controller and half the time the code in the Rx or the controller is broken so it doesn't even work when you do bind it with telemetry. It doesn't really matter. If you get Rx loss from the quad being close to the controller that's normal. Radio waves don't work when very nearby. If you're getting it at a distance, check that your antennas aren't slammed up against carbon or aren't bent up or cut up at the very ends. The ends are the important parts if you're using anything but crossfire. For Crossfire you need to have it isolated and away from the frame with a vertical orientation if possible for best signal.
@@Kababthe antennas are coming our the back pointing up like a V. Maybe those rubber tube covers are smushing the tips of the antenna like u said?
Nice work keep it up!
While i do have plenty of 6s, my Skitzo Super Nova frame is on 4s with 2750kv motors and it has remained my favorite quad. I have not been able to duplicate it on a 6s rig.
You won't be able to. The torque at the low end just feels way better. But you also get sag on that quad unfortunately
I have the parts for a 6S 5 inch UL kwad coming in tomorrow so it'll be interesting. BH 2004 1950KV motors, Gemfan 5125, AUW under 250g. Will upload footage on my channel
It'll be quick but it definitely doesn't need the 6s. 4s on it would be plenty
@@Kabab Want to give you a quick update. My 6S 5 inch Ultralight is flying beautifully, no significant electrical noise issue. I don't think it's necessarily quicker than 4S given the lower KV (1950) but am liking the faster throttle response and less sag. Test flight footage: ruclips.net/video/LbKmPqfciVU/видео.html
Hey, Kabab! Things are pretty difficult in brazil rn and i want to invest on a radio that i'll stay with until it breaks. Should i wait more for something new that is coming or the radiomaster is enough? Thanks!
There's no radio out there that stands out as really any better than anything else. I'd recommend waiting even though I'm not totally sure what's coming. If you were to get one now, I'd recommend the Jumper T18 actually. It just feels better quality in the hand. They're extremely similar however.
This has my interest peaked in building a 5” 3s quad. Based on this video and the description on your website, as long as it stays decently light, 3s is something you actually recommend for the higher kv 2203? Also I flossed this morning😉
Yes exactly. This quad on 3s will be awesome
KababFPV thanks for the reply I think I’m going to try it! Do you plan to revise the power pick at some point? I think I’m going to build one out but looking at a few other options like the pyro ul5 frame
great work on the video, finally get half of this stuff lol.
Wondering if you could do a video on PID tuning. Not long flight an explanation, but an explanation of each and how it effects the flight characteristics. What I mean is not do a quick “ this is how you do this” and then a long flight with not much going on.
Oh man that's a shitty topic 🙈. So many different opinions that all I'd get I'd hate for doing anything differently than someone else
my answer is NO! on planes and gliders, it's better and easy to understand why a machine is made for 2s, another is in 3s, also after 4s, 5s, 6s, 12s! and it is easier to understand why it is simply a question of mass / propellers, motors, size, in short, everything has a meaning and each of the aces batteries have a role to play on certain machines .. that's why for a light machine, you need a light battery, not one that doubles the weight model! .. in short, I'm not an engineer too!, but for me it's a simple problem of mass / power ..
So is it possible to create an esc that account for this? Or it would be to inefficient?
there are probably some tricks that can be invented to compensate a little but why not just run 4S when you don't need more voltage?
@@Kabab I was thinking a bit on the question, and for little quads i understand, but for bigger quads, would not make sence to convert voltage to amps, so the battery don't have to work so hard so it lives longer? I don't know if it would work like i think. Usually it is not that easy :D
The motor jitters in 4s due to high rpm compare to the 3s and the design of the motors. Have you seen the video of the slow mo guys spinning a disk, at the very high rpm the disk wobbles. Like in some power tools like a grinder or circular saw, blades have rpm limits.
I'm not saying the design of the motors are flawed it's just design for a specific application and i hope to get a set of those.
I believe this to be partially the reason why as well other than the fact that it's working perfectly on other frames.
I have not experienced 6S yet. I do have some brand new Ovonics waiting for a my rebuilt Flossstyle. To me 4S is plenty for anything under 5in, and still feels just fine on a 5in too. I do plan to build a 7in LR quad and use 6S1P 18650 packs. High voltage makes more sense the bigger the props are.
Bigger props are more load so you definitely need the voltage benefits. Dji even moved up in voltage for the phantom. That thing started on 3s
@@Kabab I remember being impressed by the performance of my ZMR250 with 1806s on 3S...😂
Interesting....I haven't flown a 4s 5inch setup in over a year at least....maybe I should revisit one. I do love my RCinpower 2207+ 1860s tho
Yeah this isn't original in any way. The only thing special about this more recent breed of quad is just how light and powerful everything has become. I'm running something that can probably do 150-160mph off a frikin whoop board. If someone told me I'd be doing that just a year ago I'd think they're nuts! :-)
I run 850mah 6s on my merica x 5" with vanover motors which i believe are 2207.5 1850kv motors and i get more than enough for a 2 minute race.
That poor little battery 😅