Whats better for 12v Lithium 3s vs 4s
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As nearly all 12v stuff is designed for automotive use it is most common that is has an operating tang of 10.5 to about 15.1. A 3s system is over taxed and under power for such a work load in comparison to the 4s. 3s has to be max charged to give any range at 12 and above where as 4s has it in spades. A slight under charge adds life to a4s and stopping discharge at 12.2 would also add Life. Comparing the two with flooded lead acid that only has about 35%discharge and such a short life, lithium in either combination is better. I think for the money we spend to build these packs, that the 4s with its longer life span is money better spent! Thank you for the great videos Jehu!
of all the comments here, this one is the most informative.
I have a battery charger that runs on 12V and i have some 12.6 3S scooter prismatic packs to charge from it. It sucks, i really only use one third of it.
Tow Mater please help! I can’t seem to find those buck converters to dial back my 4s pack’s 16.8 voltage to work with my sine wave inverter!
Jazz marcel Just search DC to DC Buck converter on amazon. This one aid adjustable LM259.
@@Jazzmarcel the only way is to build it and I think you’re from Nigeria 🇳🇬 because it had to find electronics kits here in Nigeria 🇳🇬.
In the end 24 V has a lot of advantages : smaller wires/longer wires wider voltage tolerance of devices, battery easier to manage, and 7S.
I USE 4S PACKS FOR MY 300W INVERTER I TRY TO KEEP AT 13 TO 15 VOLTS WHIT A COUPLE OF DIODES AND WORKS SO NICE AND THIS IS CHARGING WHIT 100W SOLAR PANEL , IS VERY USEFUL AND SAVE ME A LOT OF POWER!!!!THANKS FOR SHARING
To add to this, when using 3s battery system, you need to increase the ampere of the battery pack so that it stands the long time duration and by using this method it will mashup with any type of 12volt inverters instead of using 4s battery system which will select some brand of inverters
My testing with 24 used cells in 3S comes out to right around 12v which doesn't allow for much use before the inverter freaks. Better off using 4s for those cells because they won't always get to 4.2 anyway. I find 4.15 - 4.17 about as charged as they get
Hi Jehu, “Victron” make inverters with programmable upper and lower limits. Their 12v inverters go up to 17v so perfect for 4S. Another point to demonstrate is that each time you add Li ion batteries in series the transient voltage range from flat to charged becomes larger. 1S = 3 to 4.2 so 1.2v range. 2S = 6 to 8.4 so 2.4v range and so on. Easier to demonstrate in a chart. Keep up the great vids and trim out a little waffle :-)
@jehugarcia thanks for the clear video. @totes dev, roger that, the present Victron Energy Phoenix series inverters support anything from 9.2 to 17.0 Volt. Will work fine with either 3S or 4S. I think they did this on purpose in order to make them compatible to LiPo cell configurations besides good old lead-acid. Not sure about availability in the US of A. Victron is made in The Netherlands and therefore easy to get hold of in the EU and Africa. Robust overengineering by Victron make them the first choice for critical applications like emergency services, medical and military. Probably a bit overkill for the average hobbyist. I have a small 250VA inverter in my car and it seems very reliable. In the future I might use it in combination with a 4S LiPo pack.
I like how you put a condensed version of the stream on RUclips.
My portable computer project already has a buck/boost ATX PSU to run the computer, and a buck/boost DC to DC converter for the twin displays in the lid. Both will run from 6 to 30 VDC, and the AC power supply is a 19 Amp 13.8 Volt unit.
I had already decided that LiFePo4 cells would be best for battery power. While I may pay a bit more, I'm planning to get my cells from a local eBike shop. I'm hoping I can get a good BMS there, too. If not, there are other options.
That sounds awesome! Care to share any more information or photos? I have a similar system I'm working on using a low-power embedded motherboard.
4S is probably best and under charging would also make them have a longer life.
How long does it take to charge with 4 batteries 18650 with 12V bms
The Xantrx Freedom X inverter has an adjustable LBCO of 10.0 to 12.8 volts and a High Voltage Cutout of 18.0 volts. You could use either 3s or 4s with this inverter.
I tested 3S 12vdc vs 4s14.4vdc for my portable boombox. The Kenwood amp m3004 will operate at 16.6vdc so by the time the bms shuts off at 11.2Vdc I have outlasted the 3s version by 30% as well as having more power because the higher voltage allows for greater amperage to be delivered.
I've run 3s as a test to my larger system I'm building, I charge to 4.0 and go down to 10.5 or 3.5 per cell. I've found on 3s you are getting the best meat out of the discharge curve. There's very little up above 4.0 and little below 3.5. Have a look how quick the fall off is after 3.5 when discharging I'm getting around 70% use, which is perfect as far as being kind to the cells and cycle life. I pull 1.2kwh out of my 1.8kwh pack of 240 x2ah 18650 pack. 8 months and haven't needed to balance the packs. Discharging to 3 or lower I think my packs would become unbalanced.
How your pack 3s is going, Jestronix?
Viver Motivado - I moved house so it’s in storage , I’m going to 7s when I set it back up. But ... my inverter blew running at 10.5 , I suspect it didn’t like going that low.
So do you think what I'm asking above is not correct or is inefficient use of the batteries? I'm just worried 3s isn't going to power my cheap inverter, and maybe won't work at all for my 12V to 24V CPAP adapter. I would prefer 3s for sure, it's certainly cheaper.
IMPORTANT - You should also note that you are using a pure sine wave inverter which is what household electronics are engineered for and the cheaper inverters are square wave And if you want to look up the science behind it, you're more than welcome. But basically your electronics will run hotter with a square wave that can create potential hazards and drastically shorten the life of your electronics.
In yesterday's live session, I too had brought this question. One of the guy @JulianRandomProjects suggested that a lead acid inverter can be configured to set the cutoff limits by changing the resistance. And then I looked into it and he was right. It can be configuration to exactly our need i.e. 9v- 12.6v. There are 5-6 resistances and preset to configure lower cutoff, and so does for upper cutoff voltage. And this would work in almost all the inverters whose pcb is not multi layered and which don't use a single micro controller instead of multiple individual components. Some people call these inverters a Digital inverter. I don't know whats the correct term.
In general anything you import from China is highly probable that would be multilayered PCB and would not be suitable for it. In my country, 12v inverter system is used in almost every house and all the local brands are configurable. On gathering information about pros and cons of these two types of PCBs from local repair shops, came to know that the Multilayered PCBs are better choice for longer run unless you play with it. The local PCBs have much more components and their some of individual components tend to fail after some time. So they are easily repairable but don't have that great life without going anything wrong and those multilayered works great for a long time without any issues if operated within their range
Yup there a lot hacks out there
4S 2with undercharging will give a very much longer cell life though, as you will not have as much cell degradation. Might give you 5000 cycles of full discharge compared to 1000 for the 3S version, plus you would have much more usable capacity of the battery pack anyway.
Better still is to modify your load so as to be able to use the 4S full charge voltage, or use a cheaper inverter with modifies sine wave instead, which is a lot more tolerant of input voltage range, though it likely will need slight modification to have better smoothing capacitors on the input side to handle the higher ripple current.
Modified sine sucks. Damage electronic fast.
noob here thinking about trying to build a car battery with all the 18650s I have. I think a 4s pack, charged to only 3.6v per cell, would be perfect as far as voltage goes. Can a pack like this be re-charged from a car's alternator, though?
Pro tip : you can watch movies on Flixzone. Me and my gf have been using it for watching a lot of movies these days.
@Edwin Jordy Yea, been using flixzone for months myself =)
The reason why the alarm didn't sound till you wear at 16.3 volts has to do with the components used in the inverter if the inverter is built with cheap components, it will have an accuracy of +/- 10% if it built with quality components they Will have an accuracy of +/- 5%
Discharging to 3.33V has one great advantage: in case you don't discharge the battery completely, the number of cycles considerably increases in comparison with discharging to 2.8V or even 3.0V.
TLDR: Use 4S, limit charging to 4V per cell, and use a BMS to cutoff at 2.8V.
Easy.
Yes but charging to 100percent has shown a significant decrease in life cycle even if only discharged to 30% so whats the answer for long lasting cells because abuse to batteries is overly natural in human nature to not care or have a long enough attention span to matter. So like 95-20 lol idk cause all batteries degrade and after 5 10 years have to be replaced. Help
I'm siding on the 3s because most the inverters are designed for led acid being around 10 to 14 volts I would still bms limit the battery to cut off before the inverter cuts out just because we'll fuuuck that beep lol maybe raise the charge current ?? To keep up or does this effectively lower cell life like undercharging does..
Wrong: Buy Lithium Phosphate. 3.2V nominal. Perfect match for 12V systems.
@@Cuplex1 can you recommend a DC-DC converter?
@@w8stral are they not expense and hard to charge ?
Awesome video.
LiFePO4 is definitely the way to go for 12-volt gear, we just need to parallel them to get greater capacity. Li-Ion is not a deal breakernot. try 3s2p-3s4p without the DC/DC buck, or 4s2-4p with the buck or under charge.
I really enjoy these problem solving videos.
Thanks for sharing
I should have known I would see you here :). I'm currently in the process of building a headway based LiFEPO4 battery system thanks to you.
The problem with LifePo4 is that it requires twice as many cells to get the same amp-hour rating. The PLUS with LifePO4 is the high discharge rate like 125A. In building my boom box using a 30A audio amplifier, I ended up going with Sony VT5 35A discharge with 2.6 AH with only 4 cells whereas for LifePO4 I would need 8 cells (2.2AH). And if I go with 8 Li-ion Sony VT5 cells, I get 5.2 AH.
10.32 “Who’s good at math here?” just when I was asking myself why Jehu needed a calculator for this video. LOL.
I have a 4s set powering a 12v mini monitor. Fully charged runs fine
That inverter is meant for automotive use, so flat battery is around 10V, and faulty alternator may give you 15.5V. 13.8-14.4V is typical voltage.
The best option is 7S with a 24v system. I have a set up in a cabin running off grid, with a custom charger, and it works well down to 2.7v/cell. You also get a more efficient system than 12V as there are less cable losses from carrying half the current and the 24v inverters are slightly more efficient. The only downside for most people is finding a charger that does 7S. My design uses a simple voltage limiter, with a mosfet to bleed current into a resistance at a 4.20v trigger point for each parallel cell pack, this allows series charging to exactly 29.4v with all cells remaining balanced.
Or a 7s for a 12 V system will work if you use a 12/24 V solar charge controller and run power from the load terminals
For Full Discussion Check out the Live stream here www.twitch.tv/videos/252746451
4s is 100% the way to go. This inverter, and a lot of other 12v inverters and appliances are fine @ 16v. In this case, you could charge to 16.2, which is 4.05 per cell, and get 95% capacity out of the battery. As a bonus, not charging to 4.2 per cell will extend the battery lifespan greatly. It's almost perfect. How much more do you want? Build with a modern good cell, like a Samsung 21700 50E, and you can have an awesome setup. A 4s20p will make a 100ah pack that can put out 200 amps continuous, and about 95ah of that is useable capacity.
Losing 200 out of 2200 is 200/2200 = 9% loss
You wouldn’t really be loosing anything by not full charging cause that top .2 volts drops off almost right away anyway it’s not a linear discharge so yea 4s under charge it is
Ah, this was a similar question I recently asked. Looking forward to watching this one.
Thanks for sharing, and taking the time in showing us the way to save money, and recycle.
Thanks for information and opinion on 12 volt source for a 3 wheeled mobility chair conversion from lead acid to lithium iron phosphate source.
electrical components are only good 80% of its rated capacity. eg 12 amps on a 15amp circuit is what is nominally is. cheers mang, love your videos learning to work with dc/lithium working as an electrician for about 5 years now, and we have done very little dc work, basically systems inside the cabinets eg annunciator panels n stuff like that . This has been great refreshment and I've been learning stuff i never even knew. cudo's brotha.
This 12V pure sin wave inverter brand has ones going up to 3000W with the same voltage allowance on them. There very nice.
How can you charge a 4s li-ion from solar? I am having a hard time finding a solar charge controller that outputs 16.8V
Keep you voltage on 4s to 4.0 volts per cell max to 3.3 at the lowest and you will get more cycle life out of them. I use Renogy rover elite with Bluetooth module
You can go to user and set your voltage and other parameters.
Try using a buck boost converter
Would it be better to use a larger pack (6s or 7s) and a step down transformer like you have in this video to maintain a constant voltage? Then you wouldn't need to worry about the discharge voltage of the individual cells.
My only thought is how would you be able to tell when the cells were discharged? BMS?
I have been thinking of changing my motorhome to Lithium, the lead/acid batteries in there now also can't be used to their full capacity as the life is so much reduced when more than about 30% is used. Came to the conclusion that what you did in your test setup is the way to go, but keep the 12V started lead/acid and charge it from the lithium via a dc-dc converter to keep it full. This way, you can get the best of everything, lithium could be chosen to suite the solar panel, between 4 and 10s would be good. maybe 10s ebike battery!
Geniaaaaaaaaaaaaaalllllll Thank You !!!!!
Your going to have significant losses here going from battery to battery. Better to pull the lead-acid completely.
@@jean-clauded5823 "Your going to have significant losses", i have since fitted a new Lithium and a new lead acid. Just straight in parallel, it works out well as the charge/discharge voltage difference means most of the load is taken by the lithium but still have 100Ah from each if I need it. Discharge voltage of Lithium is the float volage of lead acid using 4 X Lifepo4 cells @ 3.25V per cell, 3.65 charge. There is no number of Lion cells that will work like this.
Hey Jehugarcia! I think a 3S LiPo pack (12.6v Charged. 10.2
v discharged) would work well here because
normally people don't go under 3.4v on lipos and personally I stop at 3.7v
I can find a good few inverters with an input range of DC 9.55-15.5V
Also here's a chart I've read on a forum It makes sense to me (from personal experience)
4.00V--90%
3.96---77%
3.93---70%
3.90---63%
3.86---56%
3.83---48%
3.80---43%
3.76---35%
3.73---27%
3.70---21%
3.67---14%
Hi Jehu, that 3.3v is under load. So the end cut-off for the cell would have a much higher standing voltage so even more power will remain in the battery unused.
You should test a Victron Energy inverter as they allow 17 volts as the upper and might be better for 4s. But they also have a higher price along with the voltage.
Forget about 12V and just move up to 24V (7S). Everything works better. You can find almost anything in 24V that you currently have in 12V.
UTubeRangerBob I'm doing exactly that now.
UTubeRangerBob that's what I was planning on lol
How about 36v 10s wouldn't the be spot on
A 7S LiPo configuration works best for 24 Volt. Also advantage against 12 Volt is that the current is half and therefor your cables can be longer or you can get away with a smaller cable cross section. I would personally not go for 36 Volt because it is a less common Voltage. But it would definitely work.
Matthew Jenkinson its much easier to find components (inverters, relays, etc.) rated for 24V than 36V.
Have you seen a 3S / 4S BMS that you can set the upper and lower limits of voltage? Like that you’re reproducing for us that can’t watch live. Thanks very much. Have enjoyed your videos.
Nice video dude. This was a must needed. P.s. the books ur always recommending from diy ebike and solar are awsome.
I built 4s battery pack for my lipo field charger. All the things I've used were intended for cars or trucks so all work within 10-25v. I just buy in car charger accessories like USB ports and I even charge my Mavic 2 batteries using the guts of an in car charger. The lipo charger is 9-36v so everything wired up to my field battery pack uses 100% of my batteries capacity!
if you want a cheap battery with no voltage regulation and other electronics then 3s is best. With fully charged voltage of 3s x 4.2v = 12.6v and nominal voltage of 3s x 3.7v = 11.1v. It won't be good for longevity of the cells but that's one of the down side of cheeping out.
Year's back I thought you were BS. Going back on your video now I realize that your a fucking genius. I'm up grade my AGM battery to luthiem battery. You really are inspiring. Thanks for the doing it simple.
I just use a buck/Boost converter to keep it constant in the specified range, when the cells get low the protection kicks in and it shuts down.
Some inverters allow higher voltages, but beware. Open up and check ratings on caps. Replace any 16 volt caps across the input with something larger. Low voltage caps can sometimes blow up and make a noise like a shotgun going off.
My old, 400w inverter didn't beep and shut down at 18 volts. But it did blow up one day, prompting a replacement of the old caps!
Estimado, olvidas un detalle: el hecho de que la batería estará sometida a un régimen de trabajo más suave en 4S y porque su descarga será más lenta eso a misma carga en la salida que en 3S, quizás también dure muchos más ciclos. Según entiendo hay baterías de litio que puedes obtener 10 veces más ciclos sí las usas ej: descarga hasta 30% y en carga hasta 85%. Saludos
Okay, I am losing my mind right now... About a year or so ago, I was working on an 18650 project, and somewhere, somehow I found this really nice comparison website someone had created. I can't remember at all what it was called, but it was a really great tool where you could sort and filter a ton of different lithium battery options by type, capacity, cost, brand, size, weight, etc..., tons of different specs to sort with, and it would tell you who is selling them for the best price. It was a live tracker of some sort, and a tool people would use to find the best prices on bulk batteries.
Does this ring any bells to anyone? Might someone know of the website I'm talking about?? Thanks in advance!
In 21700 battery which is better set up for 12v system battery pack?3s or 4s?
I love how when people have a calculator in their hands suddenly people need it to do the simplest calculations... I am exactly the same way.. Things that everybody knows and can be done within a split second, such as "16 / 4" and it even takes longer to press the calculator buttons yet we still do it.. LOL
Colin Richardson Well ooh la-de-da Mr Einstein...
And many times we don't even need a high degree of accuracy. Approximations may be more than sufficient...like when converting Centigrade to Fahrenheit or centimeters to inches, and so on.
People also tend to keep writing down 6 or more digits and consider them significant when only the first 3 may be meaningful...like they'll keep writing down 4.995346 volts when making calculations instead of using 5.0V even though a meter may be accurate to only 3 digits +/-5% and +/-1 digit.
@@exgenica I know the feeling with the voltages.. I was given a 12v water pump because they said they had a hard time keeping their batteries at 12v so went for a mains powered one. I tried to question them and said it kept changing between 12v and 11.5v and decided it wasn't worth the hassel.(??) I thought it was pretty strange, not really understanding what they meant. My friend was horrified to see I was running the pump on a 4 cell lipo (between ~17v - 11v). Suddenly I realised they were trying to keep it at exactly 12v because it 'needed to be 12v'..
I told them they don't need to be "that" accurate, this wasn't even a case of 3 decimal places for voltages, or what ever, this was whole numbers!
I would rather use 4s with either a BMS that will cut out when the cells under volt with DC-DC buck boost converter to keep a constant output voltage or use diodes to drop 1V on the pack output if you are in low current applications where the diode won;t get too hot since most 12V devices (that are actually 13.8 nominal) will cut out from under voltage before you go too low on the cell voltage.
That all said, for some applications a DC-DC converter is a problem due to the noise. Also, LFP prismatic cells make building large capacity packs much easier since you just need the appropriate screwdriver and only involves some some soldering if you use a BMS.
Yeah, I think the diode idea is an excellent solution. Just got to think about the power losses. If the inverter was powering a 120 watt load there would be around 10+ watts being dissipated from the diode(s). But then again, for such a small pack, large loads are probably not going to be expected. You could also incorporate a switch to bypass the diode(s) once the battery voltage falls if you need to get the most run time out of them.
I too, often use diode(s) to lower the voltage as required. If high power is required, then high-amp Si diodes aren't that expensive. You can even use FWB thru-hole packages with screw-mount to the package for flexibility and in some cases much easier heat-sinking if needed.
Victron inverters have a voltage range of 9.2V-17V allowing voltage range of 2.3 to 4.25v per cell for 4 cells.
12v inverter usually is made for cars, where 14.4 volts is normal alternator voltage. If the inverter can't handle that much, it is junk. And an 11.5v battery is already discharged, if you can't set the low voltage alarm that high, it is junk. Now check out how clean that sine wave really is. Cheap is cheap. Good enough for light bulbs, maybe.
Jehu, most of these inverters you work with are really meant for automobile use. in this use case, your voltage in your car will vary between 12V and might even sag to 11V when starting the car all the way to 14.2 volts when driving down the highway. You get an over-voltage indicator at 15 volts because if the regulator in the car went out, and the alternator started putting out 15+ volts would cause the electrolyte to boil so you should never see 15 volts.hence the warning from your inverter.
well i bought a 12v 500w inverter in 2022. and it shuts down at 9v and kann handel 14.5v. my guess its ment to be used with a 3s in mind, but i usually dont go under 3,3v per cell. so i think it would be perfekt when it would shut down at 9,5v so i dont stress my cells. and i mostly charge them up to 4,10v via solar. im using the 20-90% rule, so i can get the most cycles as possibal.
great. you got it. use LiFePO4 4S. good for around 2000 cycles at 80 DOD . BMS and balance board a must for safety and life for any lithium ION battery.
What is the purpose of the shunt circuit?
Good video 👍 very helpful Jehu, everything is a trade off.
it's always case by case when your design is specific
any 12 volt half assed made electronics should be ok at 16 volts heck they made 16 volt race lead acid batterys fer year i seen one in the 1990s but thats that .ill test an old elcheapo inverter and see if its compatible at 16 v i figure it will be ok ..great video
Does it matter if I will only use my inverter for short periods of time? Like 20 minutes max to cook stuff. I've converter everything I could to dc to be more efficient with my batteries.
Use a 24v system with 7 cells. Inverter runs from 21-30v. Perfect.
Yeah that's the idea situation, but most people don't start off with 24v systems or more than one panel.
"What percent is that of that?" :-) Love it. Your video has useful info. Tnx for posting.
Great video, The wide input range equipment isn't that rare. What is that cool dc to dc module?
Ez 4 same as building large packs. You never ever stress the cells. You have to watch your VOLTAGE at 3. U R maxing out the cells
Or you can custom order an inverter for your voltage... Reliable power on eBay can make inverters that go to 9v
I'm looking to build a 3s or 4s to power my CPAP machine using a 12v DC to 24 DC converter sold by the company that makes the CPAP. I plan on using this for camping, but I'd also like to run a fairly cheap inverter (not sure how sensitive it is yet). It seems to me the way to go is 4s and use a voltage regulator, like the one you are using above, to keep the voltage at 11v or so. Wouldn't that give me deeper cycles on the battery and longer battery life also?
I want to build a 12 volt 10AH or better battery pack for the icy Breeze cooler I just bought.
Hi Jehu, I would like you comment on the effectivity of 3s and 4s in Motorcycles. Motorcycle charging usually cut-of at 14-16V. which one is appropriate, 3s or 4s?
I'm thinking in a proyect using 3s BMS to charge and limit the charge/discharge, and a buck boost converter to keep 12v even when the voltage is lower. That will allow to provide 12v on the output and also charge the battery pack with a 12v power source like a car lighter or a wall transformer. Of course, the buck boost converter is not 100% efficient, but has an high efficiency and allow to use better the batteries and the efficiency is about 94%.
If you use a 14v charger then you can even charge to near the 3.7v which is the nominal voltage, but you still loosing about 2.4v of max pack voltage (4*4.1 = 16.4).
I JUST NEEDED THIS AND YOU PLAYED MY FAVOURITE SONG? WoAw
What’s your fav song?
@@jehugarcia Two feet - I feel like I'm drowning. And thanks for all time spent on videos, I learned a lot!
Hi Jehu!
Just a quick update.
I Made for my van a 3s 230ah Samsung 20E 2 yearls ago.. still allmost new.. i asked me this year to upgrade it at 4s.. with 80 New cells...
just watch again your video and the specs of my cells. And can see that the Victron. Inverter can reach 9,2 and 17v ( with setting it ) .. that means i am gona stay in 3s and fix a low voltage at 3.1v and 4.1 v for top one... and gona loose allmost nothing in my case.
If that can help 👋🏼👋🏼👍🏻👍🏻
wow. the prices for these pure sine wave inverters are great.
OK you have peaked my interest, If I was going to build a backup battery for offered camping that would also jumpstart my vehicle in a pinch what battery and electronics setup would you recommend? Subbing now BTW
Here is my Question on the adding of a Buck Converter to this circuit. I was informed on other videos that the Drok Monitor is settable to limit output voltage. Is this correct?
2.5V will bounce back over 3v if it was under a decent load so may be OK depending on application.
Yes, but dangerous, depends what you are using power supply for
I just built a 3s18p battery in a Sheffield ammo box for solar backup power in my truck. I'm NOT running an inverter.
I used a china BMS 100amp (60continuous) with balance charging.
The load is two PD USB-C 6 amp. And two USB-A 3amp (boating 12-24 volt usb Outlet X2) and one cig outlet.
I have a push button switch wired to ground of a relay coil, and the switch side of the relay breaks the ground to the USB outlets.
So when the voltage drops below the relay coil threshold, it switches off.. I'm going to have to use a buck boost converter or find a relay that stays on at lower voltage. It's cutting off at 3.5 volts per cell..
I could do away with my cool LED push button switch and relay all together for a breaker switch.. and let the BMS low voltage cutoff. But I think I'm going to buy a controller to keep the relay coil voltage above 12.0 until the BMS shuts off.
Here's a link to my project
#Diy #powerbox #powerwall
instagram.com/p/CAt6sAHAJ56/?igshid=huql686w4tcg
At 4 S you have 16.8 unloaded and it should drop to within the correct range. So connect the inverter directly to a 4S pack and test.
average voltages for an inverter are 10.5 low cut off, 15.0v high input
as far as using 30% etc.. depends on the cutoff voltage of the device being used
LED lights will probably work until the batteries are dead, same for almost any portable 12v equipment, it would clarify things to open your statements with the idea of running 115 devices from an inverter, and are taking about powering an inverter,
you don't want to run lithium dead, isn't the ideal between 20% to 90%
charge to 90% and use to 20%, never go below 10% ?
I just run 4s charged to 4 - 4.1v per cell and use a cheap drop-down buck converter to keep the output limited to 12.6v and when the pack ttl volts gets down close to the 12.6 no individual cell drops below 3 - 3.2v and it's time to charge
The buck converter would need to handle the full load of the Inverter. Those are expensive!
I saw the model 3 battery packs :-( There is only 4 and there the full length of the battery box.
Heya I loved the video man 👍 I have a question regarding my 4s BMS, I just installed one for my 4s 4p battery and I got 16.40 volts out of the BMS which is good but whenever I plug my battery to a load the battery immediately drops to 11.16 volts and but it drops to 4.8 volts when I start using the load with the battery. Can you tell me what's causing this? The BMS and battery cells are brand new.
Drops voltage when under load which i believe is normal from my observation
It is not just the voltage you must consider. IronPhosphate is MUCH safer that Polymer. A small amount of abuse on a Polymer and you have a big chance for a fire.
4s works great if you watch your batteries. If your inverter shuts off at 10 volts or less the cells will be lower than recomended.
there's no inverters that you can set parameters?!!?! has anyone found a 110v power inverter with a cutoff at like 9v? or some solution for a 3s? seems like most are 11v+. i'm glad you listed this one here thats 10v... thats a little better. do that or go 4s to 16v not 16.8... so each is about 1v lost still. :/
3s is better, never worry about over discharge and just limit your charge controller to 12.6 or 12, you might loose capacity but gain longevity
Jehu Is it possible to get hold of just the BMS thats on top of that blue 10S2P battery? It´s the only bms that cuts of at 40,5V that I have found so far. cheers
The normal Voltage of a car that is running is around 14.4V if you aren't running things like a heater or A/C. So, I doubt you would find an automotive inverter that only goes up to 14V.
3s is perfect being I prefer not to discharge my cells any more than this anyway. The problem is once under a good load the voltage drop would be a bit higher causing it to shut down a bit earlier.
Hola jehu, saludos desde México city.
Me gusta mucho tu canal, pero me parece hablas un poco español, y me gustaría que hicieras un vídeo aunque sea sobre las baterías 18650, ya que hay muy poca información sobre el tema y la verdad tu eres el maestro en esto.
Muy buen canal.👍🌵
You listed that you use 1/8W resistor legs for fuses....would using 1/4W resistor legs for fuses allow a higher amperage flow before blowing compared to the 1/8W resistor legs?
Hello... greetings from EL Salvador central America.... I have a question, can I keep the 18850s just as they are grouped inside the laptop battery? because I have noticed that you always cut them to have them apart.
I just have an inverter that shuts off at 10 volts, so i dont really need to put in any effort other than to swap batteries and hook one up to my solar panels
If using a BMS, why would any cell go too low or high? If any one cell , goes too low/high ,doesn't it shut down output/input and try to balance?
Does this sound right?
Samsung 26F = 3.60v Using 26F at 3S = 10.80v & 4S at 14.40v
Samsung 28A = 3.75v Using 28A at 3S = 11.25v & 4S at 15.00v
I think using the 28A in 4S would be the best for most inverters that limit at 16.00v
But remember that 3.6/3.75 is only nominal.. they have to be charged higher to get most of the capacity
26F = 4.2 Max
28A = 4.3 Max
Would it still work?
Would you also charge the battery through the buck converter or would you have to charge the pack at it's own voltage?
I have 3.7v per cell 5000mah 50 pices and I want to make 12v which should I go for 3s or 4s
Theo V Hello you must have this converter
here is the data of that converter
Product sheet Victron Phoenix 12_1200 Inverter
It goes from 9.2 to 17.0 volts
Can four of the battery banks connected in parallel work to increase the watt hours
Just open that inverter up and kill that buzzer and then you can get some more capacity from a 3S setup without annoying sound.
Have you ever seen a lithium fire? I would highly advise against that, I'm not being a safety nazi either, I'm all for a good short cut. But I've seen one single 4s battery 1300mah, have thermal runaway, and catch fire. At the time I saw this, had been a firefighter for 15yrs, i had never seen anything so small, burn so hot so quickly . it was on a plastic table 5fr from the wall, and 3ft from a cheap plastic drone, with in less than a minute, the drywall had caught fire and the plastic drone looked like a puddle of red ice cream. They're no joke.
Jehu, hopefully you see my question. I saw this video and wondered if there is a preferred battery chemistry or lithium battery that is preferred for 12v applications. I have a popup trail that runs on 12v. In your video you discussed the usable capacity of the 3s vs 4s battery configuration. What battery type would you recommend for 12v battery builds?
LifePo4!!! The voltages better match 12v systems.
question? if you use a buck converter to limit voltage once the voltage drops below that limit will it operate normally as the voltage falls? and a side question. are there buck converters that can handle a 2-3000 watt inverter?
This is a VERY important subject and You are spot on as someone who design's off grid systems we have to get a bit more reliable. Normally we build batteries withva higher volts say 20 VDC and run a power regulator. The down side is such regulators can be very expensive. For my personal use on my off grid camper , I used 4S and build a cheap adjustable power monitor that couples directly into my battery reading cell voltage it can be done will 3S or 4S just that's my preferred route. Thanks for the info and keep up the videos just subscribed. This subject is hot and heavy with off grid folks and it looks like lead acid batteries are becoming obsolete THANK GOD 😁👍 also I build my own inverters so I can set my threshold much higher that 16.3VDC normally 18 would be to high because of component ratings.