I just ordered my first ebike and I am getting ready to build my old bike with a front wheel kit. Now I am considering building my own battery for that project. Thanks to your channel.
100% of failures I have had have been due to the bms. E boards, e bikes, builds or that I've bought. When you buy a battery pack eventually it fails let's say 3 months. You will think you got it wet and you buy another thinking you were at fault then the new one fails. Eventually you will get really mad, then you take off the shrink wrap check all the cells, everything seems good then you inspect the bms and you see aluminum oxide and sometimes burns. At this point you get really angry due to the money you have spent. I don't think anyone has designed a pack that cells can be released and put back quickly and charged completely. Anyone who reads I hope it helps. It's not your motor, it's not your speed controller, it is the bms. If you are loyal to bms units you will be walking home a ton. I highly recommend you not use a bms and charge each cell individual with an 18650 charger-i have 3 exakt chargers and I can charge every cell to its fullest capacity quicker than with a single charger and pack. E bike school has great Vids if your just starting and I hope this comment helps someone, I would have save a painful large amount of money if I had read a comment like this one. Cheers
I have resorted to doing both, as I was paranoid I connected both bms and balance wires on same battery and have compared the charging voltages of both. Happy to say that the bms has done a great job, only straying one hundredth of a volt at times after charging, but I like the convenience of having the balance wires as well for easy checking what is going on.
I think the added balance wires in addition to the BMS is a great idea, wouldn't be much added cost but would give us a look into the sealed battery to periodically check.
I built my first battery by following the instructions from your videos and used all of your components . I really like the idea of having a BMS monitor the batteries for me. Keep up the good work.
I’ve used BMS’s (and even bought a few off of your website) but I’ve found that no matter how much I spend they usually fail sooner than later. Now I have a battery voltage gauge and a cheap volt buzzer that is set to the lowest I want it to go and shows me the voltage of each group and how far they differ from each other. Plus a balance charger. Great video Micah!
I use smart BMS in my both E-bikes. It cost just little bit over the regular price BMS but they comes with USB and Bluetooth connectivity. I connect it over Bluetooth to my smartphone. Over the app you can set and monitor in real time so many things including speed that you travel, temp of battery and BMS, Voltage or see all individual cell pack, you can disable/Lock BMS like E-lock. You can see remaining range... It has so much useful info and you can set parametars over app and program it however you like. You can set discharge,charge limit, phase amps, capacity of battery, Discharging low limit, charging high limit and you can set bettery balance to charging only or all the time and so much more. Smart BMS are the best thing ever.
There is one other option;I use individual cell chargers for each cell. I place them in series in a pvc pipe with threaded end caps . The caps are drilled through the middle and small bolts inserted to contact the - + ends. Wires are then connected with appropriate connectors for easy removal. When the display shows a low symbol, one end cap is removed and the cells are removed with a telescopic magnet.They are then individually charged in the chargers( 4.19vdc). The whole process can be done in under five minutes. It’s not necessary to do this for every charge if matching cells are used to begin with, and they can be charged within the tube with a regular, multicellular charger. I think the extra two minutes to extract and replace them for individual charging is worth the effort for peace of mind.I suggest using button top cells for this method, but have also used small magnets to secure the connection between the cells. I have considered spot welding nickel disks the positive ends also if non button end cells are used. They just need to protrude enough to still slip in and out of the individual chargers without a struggle. The double cell chargers are cheap but reliable for years. They charge a variety of cells and automatically recognize each type. They can be adjusted individually for either 500 or 1000 ma each cell has a digital voltage display as well as blinking bars to indicate active charging. They will not charge over- discharged or defective cells.Works for me, but I’m not picky.
You would be amazed at how many EV owners I know who think they understand what a battery is and how to manage it properly when they talk to auto electricians (many of whom are also quite inept) but totaly miss to understand it! This is the perfect video for all of them, EV owners and EV technicians alike. I would just add some graphics and schematics and voila!
I own 13 battery packs for my cordless tools. They cost a small fortune. I got tired of the factory installed bms shitting the bed every once in a while so I installed new higher capacity 18650s and bypassed the bms. Charging takes a lot longer but I've never had any failures since. Imho I prefer the reliability. Thank you.
On my OpenPPG paramotor, I have elected to only use my BMS for charging and then monitoring my voltage to decide when to setup for landing.....usually around 80 volts on my 24S battery. Using the BMS to monitor discharge, the BMS has failed me 4 times resulting in battery cutoff and emergency landings. (BMS units will eventually fail.....to me, that is unacceptable in aviation.) I do use an active balancer though that works 24/7. It is mounted inside of the battery....works great! Like you stated, everyone's situation is different. Thanks for posting this video. Bill
I have made loads of lithium batteries, and I always include balance port, even if I have good balancing BMS. It makes it easy to check if anything goes wrong. Sometimes the balancing is not included in the BMS, so I have to balance charge it. Anyway, if balancing is not included, the BMS should still be able to cut the battery off once one cell starts to overcharge.
👍👍👍 this was an excellent video. The truth is Always Somewhere in the center. I almost always use BMS, and I never rely on cheap Chinese variants. I think a BMS makes charging away from home much easier. For example if I'm charging with a solar panel and charge controller, maybe a BMS will take care of all of the issues my home charger would solve for me. I think if I were discharging on the road and charging at home, perhaps there wouldn't be any need for a BMS. I do like the over and under voltage protection though, that's critical functionality.
Yes, that is a good answer for when a BMS is neccessary : On the Road. Like on an ebike with solar panel trailer (which I'm building) you cannot balance charge during a trip. Sometimes I will plug in a wall outlet, solar charging goes on all the time, and I will use regenerative braking too. The BMS inside my packs will take care of the hassles that do not seem a big deal when you're at home.
I personally use BMSs on all my batteries. However, you can do just fine with balance charging. To prevent over-discharge, I have heard of a gadget called a low-voltage cutoff, which basically watches the overall voltage of the pack and cuts off the discharge current when it gets too low. I don't really like this because cells may be very well balanced when full, but the one with the least capacity will discharge to a critically low voltage long before the others. If the others are still high enough, the overall voltage may appear okay to the low-voltage cutoff, and it will allow the discharge to continue. I like the voltage monitor this guy shows that's wired in the balance leads. It will be watching each cell individually. If a low-voltage cut-off could be found that watched each cell individually and cut off discharge if any cell drops too low, that would be great.
Before I install the bms i always test the bms if it does truly work. I make a 13s1p and discharge the battery about 20 times. I don’t try to put the same voltage for each one of them because i wanted to see if the bms is working. If you find that one bms is working them stick to that bms !!
I was in the FPV hobby for a while and all I used for my quads were non-BMS lipos, the very idea of a BMS on my packs was absurd. As you mentioned, without a computer cutting off the voltage to your motor for you, it's very easy to just go a little bit too far and end up with a battery that doesn't work very well, which is exactly what I unintentionally did at least 3 times
@@ElectricScienceDad 4.2v per cell. Higher than that and you damage the cells. What I'll do when I don't need the extra range is charge the cells to 4.1v, which extends the lifespan of the battery pack.
IMO, you are perfectly right. I use BMSes just to prevent over-discharge/overcharge. I just use them as an additional layer of protection, along with cell fusing, slight undercharging, voltage monitoring, using quality cells, etc.
See, some people don't understand about BMS and without it BMS can use on the used cells. If your batteries are new, you will be ok. And make sure you have Good connectors. Also right changer..
I just deleted my comment, because I just noticed yours, and that's exactly what I'm planning to do as well. I'm closer to a novice though, so I'm glad my thinking was correct.
You don’t need to be quite that stringent with li-ion cells as decent quality cells paired with a good quality bms that is spec’d correctly for your current draw requirements then the bms will way outlast the cells you plan on running it on. If you plan on building the slightly more juicy lithium polymer based batteries then this is a good safety net idea
Here’s a mind bender; what about a combination of lithium titanate and supercaps?lithium titanate (headway) cells for cold charging safety, and supercaps to handle the high discharge burst on steep hills.
The only video I have seen with the most important information on it! DIY batteries is not for the faint.... I need your help with the ebike 48v lead acid setup, popping and arching upon connecting, what is the best way to eliminate the risk of failure?
I use the 3rd option , no bms , also no balance charging . I use "high ceiling" method , 48v charger can charge up to 55v , i use 17s Lifepo4(55V) instead of the norm 16s(52V) to make sure my battery never reach full charge , so that the fast charging cell never reach 3.65V which is the limit for Lifepo4 battery
I think the best practical solution to charging cells is to allow them to be removed easily and charged individually like with an xtar vc4. You will know status in real time. Any pack I have bought had bad cells that affected the charging of the other cells. Quality of affordable bms is really bad and balance chargers the same. You need to have the ability to charge each cell and see its status. The diy kits like verzund are very good. Anyone who reads this know that u will save a lot of money on your build and long run as well. These batteries are dangerous btw. I don't think them rubbing against each other in a shrink wrap is very safe! When an 18650 shorts it doesn't spark, it glows red like a coal in a stove and ignites the other cells and from experience I can tell you some will take of like flaming arrows. Always check voltage of cells when they arrive!
I put my cells in a pvc pipe, screw on the threaded end caps and extract them with a telescopic magnet out one end. They are always charged and monitored individually with multiple chargers. There are several ways to mount the straight pipes on any bike. Can even make them look fancy. I’ve done six so far.
Do one yourself or send money...You might want to add 'please'. These guys do the work and we get to learn. Sure they may make money from it somehow, but social norms are still at play.
I have been reading alot of forum online some are saying it is safe, some are saying that it will overload the BMS and some are saying that just add diodes and it will work fine. My problem is, i cannot make a 1 x 72v battery pack because it will not fit on my scooter - the plan is to connect 4x18v pack (with BMS Each) and connect them in series to get 72V. and take advantage or charging the pack aswell using a 72v charger.
Voltage balancing charging is crucial. there are 3 differences between cells, within a battery. 1, capacity. 2, equivalent series resistance. 3, self discharge rate. I always use balancing at the end of the charge, making sure each cell reaches 4.16 volts each. During use, I do NOT balance. At the end of their capacity, there will be some unbalance, due to those slight differences in capacity. When measuring during charge or discharge, the cell with the highest ESR, will show the lowest during discharge, or highest during charge. balancing while loaded can actually throw the cells further out of balance, worse than useless. so, after discharge, allowing the battery to remain coulombically balanced, at the top of the charge, they will fall back into line, pretty close. then, the balancers only pick up the slightest differences. If a battery sits for a long time, you will notice a difference in voltages cell to cell, because of different self discharge rates. for that, charging until the first cell reaches cutoff, then turning on the voltage balancer, will equalize the cells, without putting any at risk. I guess that's when a true BMS would be a good idea, since it could monitor for the cell with the highest voltage, then automatically turn on balancing, minimizing the chance for an error. For day to day use, balance charging is the way to go, NO balancing during discharge. Let each cell discharge exactly the same number of amp hours. If you know which cell has the lowest capacity, you could monitor just that cell, and tell when the battery as a whole, is discharged.
I’ve never used any balancer at all. I’ve come to the conclusion that li-0n tech is li-in’… it just ain’t worth the headache, and headache it is! Thousands in money and time down the drain. Gimme a good ol’ Yamaha 200. 85 mph and 80 mpg!I might give the lithium titanate cells a chance before I cave since I got ‘em.. they are supposedly cold tolerant… can’t wait for the uranium batts to hit the market . Better yet.. head for the hills and get a horse! And still better… get a burro! They can go three days without water and eat sagebrush! Blehh I’m losin it!!🤠
Question. If i were wanting to run 2 72v batteries in parallel when each battery has their own bms built in, is that possible? I know that you need to be carful of the voltage on both battery meaning they ideally need to be identical voltage. Im talking about 2 identical 72v batteries. Charging them separate. Just if i were to run them parallel would there be issues because there is 2 bms’s in the system? Thanks. This is a project for a electric full sized motocross bike!
Great video! I will always choose to use a BMS for my 18650 battery pack. It helps protect the battery in overcharge and over-discharge. It helps to prevent damage and fire. :-)
Thanks for the information , I use a form of BMS on my lipo batteries for all my R/C crawlers and racers , but my Venom Pro 3 does all of it for me . I think I'm upgrading to the Venom Pro Quad Charger next . Im going to start looking now for a charger that will do it all for the E-Bike I get !
Another great video Micah! Really informative! My dolphin style 48v 11ah is dying on me after 2 years of heavy use! This time I'm not going to buy another one, I'm going to build one using the advice in your videos! I will be using a BMS!
FrostGhost HD If your building your battery pack what do you think you’re gonna connect them with ? solder them or spot weld ? If your answer is spot weld then please try to buy the arduino one Micah reviewed because those sunnko ones are unreliable and don’t quite work right ! Tip suggestion : use battery spacers as the battery will be quite easy to build and will take you less time ! I tried connecting them with hot glue and i spent way to much time organizing them which made me go back to the using battery spacers
Thanks for the advice! I was planning on soldering because I don't have a spot welder. But I will see if I can pick one up for a cheap price! Thank you
believe it or not i made a spot welder using a www.ebay.com/itm/Spot-Welder-Time-Control-Board-100A-Updating-Current-with-Digital-Display/263416943097?hash=item3d54df91f9 and using the transformer from my failed sunnko spot welder
Trust me if you buy the arduino one you will not be disappointed as it is very reliable and not as dangerous to your house. when i was using the sunnko spot welder my entire house’s lights flickered when i spot welded and I did get complaints from tenants for lights
@@TonytheCarEnthusiast if you have that problem then you need some coil to smooth pulses. Get longest extension cord. I had 15 meter long. Roll it in circle and connect to your welder. Problem with circuit braker or filckering should be gone
after using off the shelf cheap BMS's I decided to design my own with an arduino at its heart and where possible off the shelf components and premade arduino modules. this minimises smd soldering. It is not an all singing all dancing device it does just what I think it needs to do, there are other devices that can handle the missing functions IMO. would you like to have one to look at when it is completed. kendrick
Old video now but seems BMSs have a tendency to fail... In the RC world this is a non issue since electronic speed controlers have a low voltage cut off which prevents the user from over discharging the battery. Charging is also quite easy, just use the same profile you always do (just plug 2 plugs instead of 1). Do larger electric vehicles usually have a low voltage cutoff? Unless things have progressed in the last 4 years it sounds like a BMS is more trouble then it's worth?
Jonathan Braud what lipo charger have you used and are you balancing 7 cells one time then 7 next ? i haven’t found a lipo charger that goes all the way to 14s
Really good video. I appreciate your not going BMS only route!!! I personally went to the dark side (not extreme though). I have connectors that I've installed on my mega battery (ebike DIY battery 14s10p) that enable me to split my battery in two for charging... and I use an iCharger Duo.... so that I CAN keep an EYE on all segments while charging. I do appreciate your advice on installing segment alarms, they're pretty cheap and I honestly hadn't thought of that.... though I tend to hang out in the top 2/3rds of my battery's range (can't deal with the lack of power in the lower range). The biggest problem that I have with almost all BMSs is that I can't tell whether they're working ...most of them are just boards without any interfaces. I'm the kind of guy that would really like to see the progress or error codes or status..... and yes, I've now paid through the nose with the iCharger Duo. I do like my set up. the iCharger is small enough to pop into a small backpack with my iPad pro or MacBook. I keep a 750W power supply at home and one at work as well so I don't have to lug those around as well. I should send you a pic of my finished battery - been using it for a good while now. Thanks for all your help previously and keep the awesome videos coming!!
Can you explain the way you constructed the dual BMS system for the car? Also I was considering putting the outputs of a few finished battery packs (PB120B1) in parallel parallel. They use a DLX-HT-3S6A BMS internally. I am wondering the proper way to protect them, and if they would be switching between charge and discharge, since the BMS only has 1 pair of wires that are used for both the load and charging.
I have never found a balance charger (hobby charger) that would do more than 6S. So when I want (as per your example) a 36 volt or 10S battery, I have to make two separate 5S packs, that I can balance charge individually. Is there something I'm missing? (like a source of bigger chargers?) Personally, I like doing my own balance charging, but it would sure be nice to plug in a single charger for my 72 volt pack!
If you could interleaf voltage dividers, you can put as many cells in series as you want. Even electric vehicles, running well over 300 volts! A divider can be as simple as two identical resistors hooked up the positive input of an OP AMP, then connect the output to the inverse in of the op amp. you connect the resistors, and the op amp power pins to the outer terminals of two series cells, connecting the output to the interlink between the two cells. If you have three, take another divider, and connect one terminal to the middle of the first two cells, the other to the terminal of the third cell, and the center tap to the junction between the second and third cell. I wish I could attach a schematic, but I don't know how to do that on a reply. You will need exactly 1 fewer dividers than the number of cells in the battery. It could be good if you use relays, so you can connect them near the top of the charge, then disconnect them when the battery is in use.
ICharger makes 8S and 10S balance chargers. They are not cheap as they can handle high amperage for large packs. Search for vendor Progressive RC. Been using these for years and vendor is very good.
@@alcusminix5527 Yeah im Ditching my BMS and doing it like this. My controller shows me through bluetooth what voltage app is and it will cut it off it want to, i u much rather do this.
So two identical BMS boards can be connected in parallel to one battery pack and it does not cause any troubles? Also, is it okay to power each BMS separately from different chargers in theory it should boost charging amps and what is more important what if power each BMS with different power supplies for charging will it cause any damage to bateries or maybe overload the BMS?
My 1st e-bike battery was a 10s2p. I had soldered the cells and was waiting for a BMS. Started using it before the BMS was installed but a solder joint came off and one cell dropped to negative voltage. It only took a ride for this to happen. I always wait for the BMS to arrive ever since.
2:38 "most convenient way' .. what is the 'Best' way? .. balance charger? ... what about batts that have a built in protection circuit? .. how do they fit into this very neat situation?
Thank you for pacing all the details of the info. Your information is very helpful cuz you demystify how things work. I do believe even i would be able to construct a lifepo4 battery for my power needs, but first I'm gonna view more of your vids. Thanks again.
People say Lithium batteries don't do well in cold temperatures. I wanted to ask if this also will make it harder for them to charge up in cold weather since they already don't do as well in it? Thanks.
Agree 100% the truth is somewhere in the middle. The only issue I have is with your theory about price, I've seen the exact same BMS for sale at lots of different prices. It's hard to know if it's dearer because the seller is looking for more profit, paid too much for it or it's genuinely better. Have you any sellers you would recommend?
I’m rookie at BMS. Quick question...Are bms only to safely charge and balance the batteries during charging time? As far as using or discharging the batteries, does the bms play a role? Ultimately, can I use my batteries on a ebike without bms and charge the batteries later on a nitecore portable charger?
Great video... Thanks... But I just have a few questions... I very well realize the importance of a high quality BMS but I'm running onnan absolute zero budget where every penny counts... It is wise to use two of the low quality BMS (cuz they're available only in multiple quantities) ? When you mentioned the Shelby's battery with two BMS... How can that be done... ? The connections?
🇸🇪Then what about a lithium battery bank hooked up to a solar system with a solar regulator? My battery bank never gets fully charged nor fully depleted. I live in Sweden where we don’t get as many hour of sun as in America. Great video!
Essentially yes. There are primitive solutions like voltage sense/alarm gates with bypass switches for each battery, the dead batteries will stop outputting and switch the circuit to charged batteries. Though this is not great in a series circuit where you need a constant voltage.
wow , very insightful teaching on BMS, i actually use BLS which i instored in my batteries. I will like to help me if it is advantageous to have the two of them in one system.
The problem with balance charging is that it mostly exists in the RC/Lipo world. You don’t see very many chargers with more than a 6s or 7s balance connector or capability. I’m using 4 LFP batteries where each cell is 180 AH, on the spec sheet. They are used so down a bit. I have a BMS board and I may use it. Making the balance connections is trivial. But I’ve been cycling the pack (4 cells) a few times. It’s clear that one of the cells has less capacity. So as I get to the ‘top’ of that battery, the voltage races ahead by maybe .12 volts (3.6 is nominal). So as that weak cell gets away from the others, I have to stop the charging. After a few charge and discharge cycles, this simply represents the capacity of the pack (as a function of the weak cell). A chain is only as strong as it’s weakest link, and all that rubbish. If I know the hard limits of the pack, what voltages mean the cells are drifting, it’s basically time to stop the charge or discharge. Since that is a relative constant (capacity as AH or WH) simply monitoring the watt hours in and out is very precise. But I’ve found that the balancing is kind of worthless. Once the weak cell is charged, there’s no point in balancing it. It’s better just to know the ‘top’, the weakest link, and stop. So far, the cell that moves .12 volts ahead of the pack, goes right back down as the pack discharges, and the pack appears to be balanced. I have a 12s pack made from 4 Titan 6s 18650 cells (Panny GA). It’s just connectors, to get to about 42 volts and 7 amp hours. These packs are made for RC use, to replace Lipos, and they have RC balance leads. I have to break the packs down to the 6s components to balance charge. The nice thing is, I can use a balance ‘checker’ to see the voltage in each cell. So, long story even longer, over a couple of years the cells, all 24, have never wandered. I’m asking, I guess, if the normal theories of electricity don’t naturally move voltage from the high to the low, during charge and discharge? A cell will unbalance when capacities differ and one cell can give or take no more. How much can you calibrate workable capacity based on the weakest cell, thus avoiding balance issues? The problem for me, with ebike batteries and chargers, is that they set things up for max capacity, the 4.2v reading where amps drop off to some set point. In a pack with 50 cells and a lot of cells in parallel, then in series, the effects of weak cells may be hard to overcome as the cycles add up. I love these 180 AH cells where suddenly you are only dealing with 4 cells in the whole pack, and everything is totally transparent. LG makes these big cells for the GM EV’s. If you could use them for an ebike, maybe use 8 and boost the voltage, something like that.
Hi George, as I said to knoxieman.... Not using a BMS is stupid when it comes to new comers and that is why I rageed his comment, BUT! That said, he has being doing it a long time and been thorough some over the years, when using lipos I go with what is known as a smart BMS, check out Vortecks2000 on youtube another mad englishman...... But love him to bits, He's done allot of the program writing for those smart BMS's, and that is why I trust them.... It is fully customizable for top end charge and you can balance the cells as needed. to your other bit, the lithium chemistry is a fire hazard waiting to happen, if a cell becomes unstable and is charged beyond capacity it can and will catch on fire and set the rest off with it, they are not like PB's that just "pass" the current over to the rest of the cells, it just does not happen, instead, they become heaters and........ boom.... You do make a few good points, but I do think it is not good to take chances with newbies in the forum.....
This is a great Video, You explained it so well, I often wondered the two differences ,I was on the same page as you but for me explaining this to a friend it was difficult . So I just sent him your video. Great job
What you need to mention is that the bms tends to drain the battery all the time and if not charged every two to four weeks it can discharge the battery so low that it may not charge and even damage the cells.
Love from India. I'd really the answer for bms im looking for. For safety concern over discharge,im looking forward for bms.BTW i would love to read your books😄
Is it possible to install a BMS to protect against excessive drain, but add an additional wire to each parallel group so a balance charger can be used for charging? I want to use my balance charger because it allows me to lower maximum charge voltage to enhance battery life. But I don't want to mess around with installing voltage alarms to monitor voltage drop.
I like to have bms outside and check every while if my pack is still ballanced. Specially after winter time when battery tempt to become unballanced. Bms can not handle very unballanced pack
I’m about to rebuild a couple of Segway Lithium Batteries. They take 18650 3.2v 6000mAh cells. (Segways batteries have BMSs). I see some 18650 3.2v BUT 10000mAh.cells on the market! Would these be safe? Would the BMS “understand” them? I suspect that if they are appropriate, the travel range would greatly increase. Suggestions?
thanx for great vid. 2 things remain a tad unclear: 1) so a ‘balance charger’ will only make sure total batt-pack V does not exceed max. V but has no control of voltages of individual cells, right? Within a pack 1 could be 3.2V and 1 could be at 5.2V and it wouldn’t notice. That doesn’t sound good at all (Sounds like d problem of a 12V lead-acid batt where d 6 cells drift apart with age. Only way to overcome this is to go with 2V-cells where you can check voltages and possibly extra-charge d low ones) 2) why is it still necessary to use a dedicated charger when using a BMS? Can’t just apply a V (Xcells x 4.2V, at least) and d BMS will cut off current when this V is reached?
My experience with recovered cells is that a BMS does not actually balance charge cells to the same voltage but shuts off when one of the cells reaches 4.2v often leaving the others as low as 3.8v. I presume that with all new cells this wouldn't be an issue
But don't the batteries like that blue one next to you have a built-in battery protection circuit internal? Is that Different than a battery management?
I ues both BMS and balance charger on same battery 6s10p works well using the skyrc b6ac v2 charger. not on a ebike tho. its for power in a shed in a remote location. So for I have 2x 6s10p made from used cells I am building more about 6 more to add in my solar system. the powere draw will be very low say 6 10 amp. and tops of 30a in at anyone time. I plan on adding 2 bms to each battery plus a resettable thermal fuse. I am not going to add in balancing as I only plan to charge to 4 or 4.10v topps so balancing want work but plan on using the skyrc b6ac v2 charger for balancing as and wen needed. I Just not sure how to do the 2 bms do you just daisy chain the bms.
I just ordered my first ebike and I am getting ready to build my old bike with a front wheel kit. Now I am considering building my own battery for that project. Thanks to your channel.
100% of failures I have had have been due to the bms. E boards, e bikes, builds or that I've bought. When you buy a battery pack eventually it fails let's say 3 months. You will think you got it wet and you buy another thinking you were at fault then the new one fails. Eventually you will get really mad, then you take off the shrink wrap check all the cells, everything seems good then you inspect the bms and you see aluminum oxide and sometimes burns. At this point you get really angry due to the money you have spent. I don't think anyone has designed a pack that cells can be released and put back quickly and charged completely. Anyone who reads I hope it helps. It's not your motor, it's not your speed controller, it is the bms. If you are loyal to bms units you will be walking home a ton. I highly recommend you not use a bms and charge each cell individual with an 18650 charger-i have 3 exakt chargers and I can charge every cell to its fullest capacity quicker than with a single charger and pack. E bike school has great Vids if your just starting and I hope this comment helps someone, I would have save a painful large amount of money if I had read a comment like this one. Cheers
I have resorted to doing both, as I was paranoid I connected both bms and balance wires on same battery and have compared the charging voltages of both. Happy to say that the bms has done a great job, only straying one hundredth of a volt at times after charging, but I like the convenience of having the balance wires as well for easy checking what is going on.
I think the added balance wires in addition to the BMS is a great idea, wouldn't be much added cost but would give us a look into the sealed battery to periodically check.
With such a detailed, humble explanations we don’t find any alternative except start loving you!
I built my first battery by following the instructions from your videos and used all of your components . I really like the idea of having a BMS monitor the batteries for me. Keep up the good work.
Was it easy to use the BMS ? kindly advise which manual or video did you use to handle it ..
@anasmoustafa7286 same components he used in the video I used and I just watched another video to install it
It's amazing how big the world of batteries and bms is. Thank for opening that up to us!!
Great vids
I’ve used BMS’s (and even bought a few off of your website) but I’ve found that no matter how much I spend they usually fail sooner than later. Now I have a battery voltage gauge and a cheap volt buzzer that is set to the lowest I want it to go and shows me the voltage of each group and how far they differ from each other. Plus a balance charger. Great video Micah!
agreed , the BMS always seems to fail
I use smart BMS in my both E-bikes. It cost just little bit over the regular price BMS but they comes with USB and Bluetooth connectivity. I connect it over Bluetooth to my smartphone. Over the app you can set and monitor in real time so many things including speed that you travel, temp of battery and BMS, Voltage or see all individual cell pack, you can disable/Lock BMS like E-lock. You can see remaining range... It has so much useful info and you can set parametars over app and program it however you like. You can set discharge,charge limit, phase amps, capacity of battery, Discharging low limit, charging high limit and you can set bettery balance to charging only or all the time and so much more. Smart BMS are the best thing ever.
Where did you buy from?
Dariusz Czarkowski Aliexpress. Just search for smart BMS.
A bms that can balance by Bluetooth has my attention cool
All of your videos are not only spot-on informative, but awesomly entertaining! Thanks, great help.
Great video micah "to bms or not to bms"😂😂 my favorite part!
Another important feature of any good BMS is current overdraw protection which is equally important in maintaining the health of your battery pack.
There is one other option;I use individual cell chargers for each cell. I place them in series in a pvc pipe with threaded end caps . The caps are drilled through the middle and small bolts inserted to contact the - + ends. Wires are then connected with appropriate connectors for easy removal. When the display shows a low symbol, one end cap is removed and the cells are removed with a telescopic magnet.They are then individually charged in the chargers( 4.19vdc). The whole process can be done in under five minutes. It’s not necessary to do this for every charge if matching cells are used to begin with, and they can be charged within the tube with a regular, multicellular charger. I think the extra two minutes to extract and replace them for individual charging is worth the effort for peace of mind.I suggest using button top cells for this method, but have also used small magnets to secure the connection between the cells. I have considered spot welding nickel disks the positive ends also if non button end cells are used. They just need to protrude enough to still slip in and out of the individual chargers without a struggle. The double cell chargers are cheap but reliable for years. They charge a variety of cells and automatically recognize each type. They can be adjusted individually for either 500 or 1000 ma each cell has a digital voltage display as well as blinking bars to indicate active charging. They will not charge over- discharged or defective cells.Works for me, but I’m not picky.
You would be amazed at how many EV owners I know who think they understand what a battery is and how to manage it properly when they talk to auto electricians (many of whom are also quite inept) but totaly miss to understand it! This is the perfect video for all of them, EV owners and EV technicians alike. I would just add some graphics and schematics and voila!
Best description of what a BMS does and alternative solutions!
Great video! Thanks for teaching about the intricacies of BMS’s
Tu usas ebike?
I own 13 battery packs for my cordless tools. They cost a small fortune. I got tired of the factory installed bms shitting the bed every once in a while so I installed new higher capacity 18650s and bypassed the bms. Charging takes a lot longer but I've never had any failures since. Imho I prefer the reliability. Thank you.
On my OpenPPG paramotor, I have elected to only use my BMS for charging and then monitoring my voltage to decide when to setup for landing.....usually around 80 volts on my 24S battery. Using the BMS to monitor discharge, the BMS has failed me 4 times resulting in battery cutoff and emergency landings. (BMS units will eventually fail.....to me, that is unacceptable in aviation.) I do use an active balancer though that works 24/7. It is mounted inside of the battery....works great! Like you stated, everyone's situation is different.
Thanks for posting this video.
Bill
Hello, Thank you for this helpful video! Can you tell us a few good commercial BMS options for 12V batteries, please?
I have made loads of lithium batteries, and I always include balance port, even if I have good balancing BMS. It makes it easy to check if anything goes wrong. Sometimes the balancing is not included in the BMS, so I have to balance charge it. Anyway, if balancing is not included, the BMS should still be able to cut the battery off once one cell starts to overcharge.
👍👍👍 this was an excellent video. The truth is Always Somewhere in the center. I almost always use BMS, and I never rely on cheap Chinese variants. I think a BMS makes charging away from home much easier. For example if I'm charging with a solar panel and charge controller, maybe a BMS will take care of all of the issues my home charger would solve for me. I think if I were discharging on the road and charging at home, perhaps there wouldn't be any need for a BMS. I do like the over and under voltage protection though, that's critical functionality.
Yes, that is a good answer for when a BMS is neccessary : On the Road. Like on an ebike with solar panel trailer (which I'm building) you cannot balance charge during a trip. Sometimes I will plug in a wall outlet, solar charging goes on all the time, and I will use regenerative braking too. The BMS inside my packs will take care of the hassles that do not seem a big deal when you're at home.
OK, now what about BMSs on series/parallel battery packs, is it a special type of BMS or can you use a standard BMS?
I personally use BMSs on all my batteries. However, you can do just fine with balance charging. To prevent over-discharge, I have heard of a gadget called a low-voltage cutoff, which basically watches the overall voltage of the pack and cuts off the discharge current when it gets too low. I don't really like this because cells may be very well balanced when full, but the one with the least capacity will discharge to a critically low voltage long before the others. If the others are still high enough, the overall voltage may appear okay to the low-voltage cutoff, and it will allow the discharge to continue. I like the voltage monitor this guy shows that's wired in the balance leads. It will be watching each cell individually. If a low-voltage cut-off could be found that watched each cell individually and cut off discharge if any cell drops too low, that would be great.
I have seen tiny little BMS for each cell
Before I install the bms i always test the bms if it does truly work. I make a 13s1p and discharge the battery about 20 times. I don’t try to put the same voltage for each one of them because i wanted to see if the bms is working. If you find that one bms is working them stick to that bms !!
This is all good info, I’m tempted to make a battery for my Onewheel
I was in the FPV hobby for a while and all I used for my quads were non-BMS lipos, the very idea of a BMS on my packs was absurd. As you mentioned, without a computer cutting off the voltage to your motor for you, it's very easy to just go a little bit too far and end up with a battery that doesn't work very well, which is exactly what I unintentionally did at least 3 times
How high would you go on voltage for a battery that doesn't have a BMS?
@@ElectricScienceDad 4.2v per cell. Higher than that and you damage the cells. What I'll do when I don't need the extra range is charge the cells to 4.1v, which extends the lifespan of the battery pack.
Good explanation of what the BMS does.
IMO, you are perfectly right.
I use BMSes just to prevent over-discharge/overcharge.
I just use them as an additional layer of protection, along with cell fusing, slight undercharging, voltage monitoring, using quality cells, etc.
YES,IT CAN BE PROTECT BATTERY
You can use fuses to prevent over discharge. Voltage alarms are better at monitoring voltages.
See, some people don't understand about BMS and without it BMS can use on the used cells. If your batteries are new, you will be ok. And make sure you have Good connectors. Also right changer..
The safest way: use a bms AND use a voltage checker for each bank to ensure your bms is working!
That is exactly what i am planing to do
@@Kris57277 -- Me too. For the peace of mind a BMS offers, and combine that with testing (and learning) what happens inside, after making the pack.
I just deleted my comment, because I just noticed yours, and that's exactly what I'm planning to do as well. I'm closer to a novice though, so I'm glad my thinking was correct.
You don’t need to be quite that stringent with li-ion cells as decent quality cells paired with a good quality bms that is spec’d correctly for your current draw requirements then the bms will way outlast the cells you plan on running it on. If you plan on building the slightly more juicy lithium polymer based batteries then this is a good safety net idea
Here’s a mind bender; what about a combination of lithium titanate and supercaps?lithium titanate (headway) cells for cold charging safety, and supercaps to handle the high discharge burst on steep hills.
We would love one of your beautiful amazing books 📚 ❤️
I use a BMS on all my battery packs. Thanks for the informative video. Electric stuff is fun. Now I want to make an electric car.
True, electricity is fun, and tinkering with it leads (almost inevitably) to the final goal; build your own car.
The only video I have seen with the most important information on it! DIY batteries is not for the faint.... I need your help with the ebike 48v lead acid setup, popping and arching upon connecting, what is the best way to eliminate the risk of failure?
I'm just here for the free book ;) jokes aside, your videos have been critical to the planning phase of my ebike build! Keep up the good work!
Travis, congratulations. It looks like you just proved ... HONESTY is the best policy. :)
I use the 3rd option , no bms , also no balance charging . I use "high ceiling" method , 48v charger can charge up to 55v , i use 17s Lifepo4(55V) instead of the norm 16s(52V) to make sure my battery never reach full charge , so that the fast charging cell never reach 3.65V which is the limit for Lifepo4 battery
Thanks for a very lucid presentation.
I think the best practical solution to charging cells is to allow them to be removed easily and charged individually like with an xtar vc4. You will know status in real time. Any pack I have bought had bad cells that affected the charging of the other cells. Quality of affordable bms is really bad and balance chargers the same. You need to have the ability to charge each cell and see its status. The diy kits like verzund are very good. Anyone who reads this know that u will save a lot of money on your build and long run as well. These batteries are dangerous btw. I don't think them rubbing against each other in a shrink wrap is very safe! When an 18650 shorts it doesn't spark, it glows red like a coal in a stove and ignites the other cells and from experience I can tell you some will take of like flaming arrows. Always check voltage of cells when they arrive!
I put my cells in a pvc pipe, screw on the threaded end caps and extract them with a telescopic magnet out one end. They are always charged and monitored individually with multiple chargers. There are several ways to mount the straight pipes on any bike. Can even make them look fancy. I’ve done six so far.
Thanks a ton for this clear explanation. I just bought a balanced charger to start making my own battery packs
📹
Do a video on how to wire up Two BMS's👀
Yes, please i would like to see that too
New to ebikes, I have question for you. Why would you need or use two BMS’s?
Do one yourself or send money...You might want to add 'please'. These guys do the work and we get to learn. Sure they may make money from it somehow, but social norms are still at play.
I got 4 x 18v 25Ah battery pack with BMS each pack. Can i use a 72v charger and charge them in series?
I have been reading alot of forum online some are saying it is safe, some are saying that it will overload the BMS and some are saying that just add diodes and it will work fine.
My problem is, i cannot make a 1 x 72v battery pack because it will not fit on my scooter - the plan is to connect 4x18v pack (with BMS Each) and connect them in series to get 72V. and take advantage or charging the pack aswell using a 72v charger.
I really like his tutorial. Now I am fully understand about BMS. Regardless your setup, always use BMS
ruclips.net/video/pljSZcEwc8Q/видео.html
Voltage balancing charging is crucial. there are 3 differences between cells, within a battery. 1, capacity. 2, equivalent series resistance. 3, self discharge rate. I always use balancing at the end of the charge, making sure each cell reaches 4.16 volts each. During use, I do NOT balance. At the end of their capacity, there will be some unbalance, due to those slight differences in capacity. When measuring during charge or discharge, the cell with the highest ESR, will show the lowest during discharge, or highest during charge. balancing while loaded can actually throw the cells further out of balance, worse than useless. so, after discharge, allowing the battery to remain coulombically balanced, at the top of the charge, they will fall back into line, pretty close. then, the balancers only pick up the slightest differences. If a battery sits for a long time, you will notice a difference in voltages cell to cell, because of different self discharge rates. for that, charging until the first cell reaches cutoff, then turning on the voltage balancer, will equalize the cells, without putting any at risk. I guess that's when a true BMS would be a good idea, since it could monitor for the cell with the highest voltage, then automatically turn on balancing, minimizing the chance for an error. For day to day use, balance charging is the way to go, NO balancing during discharge. Let each cell discharge exactly the same number of amp hours. If you know which cell has the lowest capacity, you could monitor just that cell, and tell when the battery as a whole, is discharged.
I’ve never used any balancer at all. I’ve come to the conclusion that li-0n tech is li-in’… it just ain’t worth the headache, and headache it is! Thousands in money and time down the drain. Gimme a good ol’ Yamaha 200. 85 mph and 80 mpg!I might give the lithium titanate cells a chance before I cave since I got ‘em.. they are supposedly cold tolerant… can’t wait for the uranium batts to hit the market . Better yet.. head for the hills and get a horse! And still better… get a burro! They can go three days without water and eat sagebrush! Blehh I’m losin it!!🤠
Question. If i were wanting to run 2 72v batteries in parallel when each battery has their own bms built in, is that possible? I know that you need to be carful of the voltage on both battery meaning they ideally need to be identical voltage. Im talking about 2 identical 72v batteries. Charging them separate. Just if i were to run them parallel would there be issues because there is 2 bms’s in the system? Thanks. This is a project for a electric full sized motocross bike!
Any easy way to test capacity of 10 or 13 cell batteries. (Capacity of each individual cell Bank)
Always concise and informative. Thanks for freely sharing such useful info.
Great video! I will always choose to use a BMS for my 18650 battery pack. It helps protect the battery in overcharge and over-discharge. It helps to prevent damage and fire. :-)
Thanks for the information , I use a form of BMS on my lipo batteries for all my R/C crawlers and racers , but my Venom Pro 3 does all of it for me . I think I'm upgrading to the Venom Pro Quad Charger next . Im going to start looking now for a charger that will do it all for the E-Bike I get !
Another great video Micah! Really informative! My dolphin style 48v 11ah is dying on me after 2 years of heavy use! This time I'm not going to buy another one, I'm going to build one using the advice in your videos! I will be using a BMS!
FrostGhost HD If your building your battery pack what do you think you’re gonna connect them with ? solder them or spot weld ? If your answer is spot weld then please try to buy the arduino one Micah reviewed because those sunnko ones are unreliable and don’t quite work right !
Tip suggestion : use battery spacers as the battery will be quite easy to build and will take you less time ! I tried connecting them with hot glue and i spent way to much time organizing them which made me go back to the using battery spacers
Thanks for the advice! I was planning on soldering because I don't have a spot welder. But I will see if I can pick one up for a cheap price! Thank you
believe it or not i made a spot welder using a www.ebay.com/itm/Spot-Welder-Time-Control-Board-100A-Updating-Current-with-Digital-Display/263416943097?hash=item3d54df91f9 and using the transformer from my failed sunnko spot welder
Trust me if you buy the arduino one you will not be disappointed as it is very reliable and not as dangerous to your house. when i was using the sunnko spot welder my entire house’s lights flickered when i spot welded and I did get complaints from tenants for lights
@@TonytheCarEnthusiast if you have that problem then you need some coil to smooth pulses. Get longest extension cord. I had 15 meter long. Roll it in circle and connect to your welder. Problem with circuit braker or filckering should be gone
Great video. Could a power failure while riding be s symptom is a bad BMS board? Thanks!
Good job man
Thanks for all your vids on Lithium batteries, I bought your book on Lithium batteries and it has been very helpful
after using off the shelf cheap BMS's I decided to design my own with an arduino at its heart and where possible off the shelf components and premade arduino modules. this minimises smd soldering.
It is not an all singing all dancing device it does just what I think it needs to do, there are other devices that can handle the missing functions IMO.
would you like to have one to look at when it is completed.
kendrick
Old video now but seems BMSs have a tendency to fail... In the RC world this is a non issue since electronic speed controlers have a low voltage cut off which prevents the user from over discharging the battery. Charging is also quite easy, just use the same profile you always do (just plug 2 plugs instead of 1). Do larger electric vehicles usually have a low voltage cutoff? Unless things have progressed in the last 4 years it sounds like a BMS is more trouble then it's worth?
Good work well done
Great information as I prepare to build my EBike battery.
hi,our company professional produce Ebike battery with BMS,we have 12v 24v 10-100AH.
Been using lipo batteries with balance charging and has worked great.
Jonathan Braud what lipo charger have you used and are you balancing 7 cells one time then 7 next ? i haven’t found a lipo charger that goes all the way to 14s
Anton Pepkolaj I’m using the turnigy TQ4 charger to do up to 6s. I just run packs in series to get desired voltage.
Really good video. I appreciate your not going BMS only route!!! I personally went to the dark side (not extreme though). I have connectors that I've installed on my mega battery (ebike DIY battery 14s10p) that enable me to split my battery in two for charging... and I use an iCharger Duo.... so that I CAN keep an EYE on all segments while charging. I do appreciate your advice on installing segment alarms, they're pretty cheap and I honestly hadn't thought of that.... though I tend to hang out in the top 2/3rds of my battery's range (can't deal with the lack of power in the lower range). The biggest problem that I have with almost all BMSs is that I can't tell whether they're working ...most of them are just boards without any interfaces. I'm the kind of guy that would really like to see the progress or error codes or status..... and yes, I've now paid through the nose with the iCharger Duo. I do like my set up. the iCharger is small enough to pop into a small backpack with my iPad pro or MacBook. I keep a 750W power supply at home and one at work as well so I don't have to lug those around as well. I should send you a pic of my finished battery - been using it for a good while now. Thanks for all your help previously and keep the awesome videos coming!!
I got a full laugh out of the BMS joke. I appreciate the humor.
Great work Ebike school, all/any of your book will be of great help to me. Pls continue the good work you are doing.
Thanks for everything 👍👍👍
Can you explain the way you constructed the dual BMS system for the car? Also I was considering putting the outputs of a few finished battery packs (PB120B1) in parallel parallel. They use a DLX-HT-3S6A BMS internally. I am wondering the proper way to protect them, and if they would be switching between charge and discharge, since the BMS only has 1 pair of wires that are used for both the load and charging.
I have never found a balance charger (hobby charger) that would do more than 6S. So when I want (as per your example) a 36 volt or 10S battery, I have to make two separate 5S packs, that I can balance charge individually. Is there something I'm missing? (like a source of bigger chargers?) Personally, I like doing my own balance charging, but it would sure be nice to plug in a single charger for my 72 volt pack!
If you could interleaf voltage dividers, you can put as many cells in series as you want. Even electric vehicles, running well over 300 volts! A divider can be as simple as two identical resistors hooked up the positive input of an OP AMP, then connect the output to the inverse in of the op amp. you connect the resistors, and the op amp power pins to the outer terminals of two series cells, connecting the output to the interlink between the two cells. If you have three, take another divider, and connect one terminal to the middle of the first two cells, the other to the terminal of the third cell, and the center tap to the junction between the second and third cell. I wish I could attach a schematic, but I don't know how to do that on a reply. You will need exactly 1 fewer dividers than the number of cells in the battery. It could be good if you use relays, so you can connect them near the top of the charge, then disconnect them when the battery is in use.
ICharger makes 8S and 10S balance chargers. They are not cheap as they can handle high amperage for large packs. Search for vendor Progressive RC. Been using these for years and vendor is very good.
@@alcusminix5527 Yeah im Ditching my BMS and doing it like this. My controller shows me through bluetooth what voltage app is and it will cut it off it want to, i u much rather do this.
@@cheekonv Individual CELL Voltage ?
@@vtorsi610 yes well cell in parallel at lest i can see which group.. ANT BMS with VBMS app
So two identical BMS boards can be connected in parallel to one battery pack and it does not cause any troubles?
Also, is it okay to power each BMS separately from different chargers in theory it should boost charging amps and what is more important what if power each BMS with different power supplies for charging will it cause any damage to bateries or maybe overload the BMS?
Such a wonderful Video. Thanks a lot! :)
My 1st e-bike battery was a 10s2p. I had soldered the cells and was waiting for a BMS. Started using it before the BMS was installed but a solder joint came off and one cell dropped to negative voltage. It only took a ride for this to happen. I always wait for the BMS to arrive ever since.
2:38 "most convenient way' .. what is the 'Best' way? .. balance charger? ... what about batts that have a built in protection circuit? .. how do they fit into this very neat situation?
Nice straightforward video full of good info, Thanks Mika.
Just use LifePO4 , might be 15% heavier but they don't catch on fire and stay within balance on their own. You get more cycles out of them as well.
Thank you for pacing all the details of the info. Your information is very helpful cuz you demystify how things work. I do believe even i would be able to construct a lifepo4 battery for my power needs, but first I'm gonna view more of your vids. Thanks again.
Great video. How about one on how you set up your work bench & work area.
Great Video
Good video mate, verry nice!Thank you!
People say Lithium batteries don't do well in cold temperatures. I wanted to ask if this also will make it harder for them to charge up in cold weather since they already don't do as well in it?
Thanks.
Thanks a lot man your a life saver, is there like a reputable company or companies that make BMS that we can trust?
Agree 100% the truth is somewhere in the middle. The only issue I have is with your theory about price, I've seen the exact same BMS for sale at lots of different prices. It's hard to know if it's dearer because the seller is looking for more profit, paid too much for it or it's genuinely better. Have you any sellers you would recommend?
I’m rookie at BMS. Quick question...Are bms only to safely charge and balance the batteries during charging time? As far as using or discharging the batteries, does the bms play a role? Ultimately, can I use my batteries on a ebike without bms and charge the batteries later on a nitecore portable charger?
Great video... Thanks... But I just have a few questions...
I very well realize the importance of a high quality BMS but I'm running onnan absolute zero budget where every penny counts... It is wise to use two of the low quality BMS (cuz they're available only in multiple quantities) ?
When you mentioned the Shelby's battery with two BMS... How can that be done... ? The connections?
My hobby charger only takes up to 6S packs so... anything above would be more involved! Thanks for great video!
Great video, I had finally decided on balance leads. but now I'm thinking I might put in both a bms and balance leads for periodic checks.
🇸🇪Then what about a lithium battery bank hooked up to a solar system with a solar regulator? My battery bank never gets fully charged nor fully depleted. I live in Sweden where we don’t get as many hour of sun as in America.
Great video!
Essentially yes. There are primitive solutions like voltage sense/alarm gates with bypass switches for each battery, the dead batteries will stop outputting and switch the circuit to charged batteries. Though this is not great in a series circuit where you need a constant voltage.
(And the inverse for your charging circuit, would be a balance charge circuit.)
wow , very insightful teaching on BMS, i actually use BLS which i instored in my batteries. I will like to help me if it is advantageous to have the two of them in one system.
Share some knowledge about MPPT charger in solar panel.
The problem with balance charging is that it mostly exists in the RC/Lipo world. You don’t see very many chargers with more than a 6s or 7s balance connector or capability.
I’m using 4 LFP batteries where each cell is 180 AH, on the spec sheet. They are used so down a bit. I have a BMS board and I may use it. Making the balance connections is trivial. But I’ve been cycling the pack (4 cells) a few times. It’s clear that one of the cells has less capacity. So as I get to the ‘top’ of that battery, the voltage races ahead by maybe .12 volts (3.6 is nominal). So as that weak cell gets away from the others, I have to stop the charging. After a few charge and discharge cycles, this simply represents the capacity of the pack (as a function of the weak cell). A chain is only as strong as it’s weakest link, and all that rubbish.
If I know the hard limits of the pack, what voltages mean the cells are drifting, it’s basically time to stop the charge or discharge. Since that is a relative constant (capacity as AH or WH) simply monitoring the watt hours in and out is very precise. But I’ve found that the balancing is kind of worthless. Once the weak cell is charged, there’s no point in balancing it. It’s better just to know the ‘top’, the weakest link, and stop. So far, the cell that moves .12 volts ahead of the pack, goes right back down as the pack discharges, and the pack appears to be balanced.
I have a 12s pack made from 4 Titan 6s 18650 cells (Panny GA). It’s just connectors, to get to about 42 volts and 7 amp hours. These packs are made for RC use, to replace Lipos, and they have RC balance leads. I have to break the packs down to the 6s components to balance charge. The nice thing is, I can use a balance ‘checker’ to see the voltage in each cell. So, long story even longer, over a couple of years the cells, all 24, have never wandered.
I’m asking, I guess, if the normal theories of electricity don’t naturally move voltage from the high to the low, during charge and discharge? A cell will unbalance when capacities differ and one cell can give or take no more. How much can you calibrate workable capacity based on the weakest cell, thus avoiding balance issues?
The problem for me, with ebike batteries and chargers, is that they set things up for max capacity, the 4.2v reading where amps drop off to some set point. In a pack with 50 cells and a lot of cells in parallel, then in series, the effects of weak cells may be hard to overcome as the cycles add up. I love these 180 AH cells where suddenly you are only dealing with 4 cells in the whole pack, and everything is totally transparent.
LG makes these big cells for the GM EV’s. If you could use them for an ebike, maybe use 8 and boost the voltage, something like that.
Hi George, as I said to knoxieman.... Not using a BMS is stupid when it comes to new comers and that is why I rageed his comment, BUT! That said, he has being doing it a long time and been thorough some over the years, when using lipos I go with what is known as a smart BMS, check out Vortecks2000 on youtube another mad englishman...... But love him to bits, He's done allot of the program writing for those smart BMS's, and that is why I trust them.... It is fully customizable for top end charge and you can balance the cells as needed.
to your other bit, the lithium chemistry is a fire hazard waiting to happen, if a cell becomes unstable and is charged beyond capacity it can and will catch on fire and set the rest off with it, they are not like PB's that just "pass" the current over to the rest of the cells, it just does not happen, instead, they become heaters and........ boom.... You do make a few good points, but I do think it is not good to take chances with newbies in the forum.....
This is a great Video, You explained it so well, I often wondered the two differences ,I was on the same page as you but for me explaining this to a friend it was difficult . So I just sent him your video. Great job
quality content, thanks!
What you need to mention is that the bms tends to drain the battery all the time and if not charged every two to four weeks it can discharge the battery so low that it may not charge and even damage the cells.
Parasitic Drain varies tremendously by brand ...
Dude your just Awesome . Probably saved a couple hundred eye balls and probably lives too. Amen
Love from India. I'd really the answer for bms im looking for. For safety concern over discharge,im looking forward for bms.BTW i would love to read your books😄
Is it possible to install a BMS to protect against excessive drain, but add an additional wire to each parallel group so a balance charger can be used for charging? I want to use my balance charger because it allows me to lower maximum charge voltage to enhance battery life. But I don't want to mess around with installing voltage alarms to monitor voltage drop.
I like to have bms outside and check every while if my pack is still ballanced. Specially after winter time when battery tempt to become unballanced. Bms can not handle very unballanced pack
I’m about to rebuild a couple of Segway Lithium Batteries. They take 18650 3.2v 6000mAh cells. (Segways batteries have BMSs). I see some 18650 3.2v BUT 10000mAh.cells on the market! Would these be safe? Would the BMS “understand” them? I suspect that if they are appropriate, the travel range would greatly increase. Suggestions?
thanx for great vid. 2 things remain a tad unclear:
1) so a ‘balance charger’ will only make sure total batt-pack V does not exceed max. V but has no control of voltages of individual cells, right? Within a pack 1 could be 3.2V and 1 could be at 5.2V and it wouldn’t notice. That doesn’t sound good at all (Sounds like d problem of a 12V lead-acid batt where d 6 cells drift apart with age. Only way to overcome this is to go with 2V-cells where you can check voltages and possibly extra-charge d low ones)
2) why is it still necessary to use a dedicated charger when using a BMS? Can’t just apply a V (Xcells x 4.2V, at least) and d BMS will cut off current when this V is reached?
I use a bms connected to only charge to balance the cells and use the controller low voltage cutoff.
My experience with recovered cells is that a BMS does not actually balance charge cells to the same voltage but shuts off when one of the cells reaches 4.2v often leaving the others as low as 3.8v. I presume that with all new cells this wouldn't be an issue
Your BMS may simply shut-off at Cell = 4.2v. While other BMS can and will Top-Balance.
for a 12s4p battery, could you have a single 12s bms wire for each P or is it more important to have a bms for each P?
Gee there is a lot more than just plugging in a battery and motor for an electric bike. Thanks for the info.
But don't the batteries like that blue one next to you have a built-in battery protection circuit internal? Is that Different than a battery management?
Great video as usual. I always use a BMS.
I ues both BMS and balance charger on same battery 6s10p works well using the skyrc b6ac v2 charger. not on a ebike tho. its for power in a shed in a remote location. So for I have 2x 6s10p made from used cells I am building more about 6 more to add in my solar system. the powere draw will be very low say 6 10 amp. and tops of 30a in at anyone time. I plan on adding 2 bms to each battery plus a resettable thermal fuse. I am not going to add in balancing as I only plan to charge to 4 or 4.10v topps so balancing want work but plan on using the skyrc b6ac v2 charger for balancing as and wen needed. I Just not sure how to do the 2 bms do you just daisy chain the bms.