DIY Lithium Battery - BMS Wiring - Part 3/5

How to build a lithium battery - part 3: Battery Management Systems (BMSs)
For part 1: battery layout, see here: • DIY Lithium Battery - ...
For part 2: spot welding, see here: • DIY Lithium Battery - ...
The following parts will be coming soon:
Part 4: Sealing the battery
Part 5: Choosing an appropriate charger
The parts I use for battery building:
18650 cells (Sanyo GA 3500mah): goo.gl/J6ONJV
18650 cells (another Sanyo GA 3500mah source): goo.gl/f10wHH
18650 cells (Samsung 26F 2600mah): goo.gl/VhpP7T
18650 positive insulating washer: goo.gl/HBVOuc
Nickel strip: goo.gl/VIrNQq
Spot welder: goo.gl/KN3Uaw
BMSs: goo.gl/S6gSQx
Silicone wire: goo.gl/xmpbKD
Black 18650 cell spacers: goo.gl/hQxWF6
Large heat shrink tubing: goo.gl/6v1ow9
Small heat shrink tubing: goo.gl/OU3Z6u
Foam sheet for protecting battery: goo.gl/5e71tE
Kapton tape: goo.gl/D6BT57
Chargers: goo.gl/js0T0V
If you'd like a written step-by-step guide showing how to build an electric bicycle battery, see my article here: www.ebikeschool.com/how-to-bui...

[@EbikeSchool]

I hope you guys enjoyed my How to Build a Lithium Battery tutorial series. If you want to learn even more, I hope you'll consider checking out my Amazon #1 Bestselling book, DIY Lithium Batteries, available in paperback and ebook formats. a.co/iDtWdPX

[@Allbbrz]

Yeah, it's great. Question: since you wire 3 batteries in parallel, do you have anything that monitors that particular "cell" and tell you that it went bad ? I am thinking on the bad case that one or more individual cells is going down and the indicator would tell you which so you wouldn't have to disassemble the entire pack and test them all.

[@thekaiser4333]

Why would one need a BMS?

[@vishalsaini7966]

Brother can we 16 s bms in 15 s cell battery

[@agmendoza2830]

@@thekaiser4333 why wouldn't you use one?

[@manish4094]

Hey EbikeSchool.com I am using 13cells in series and 18 such series connected in parallels so should I use only one 13s bms aur 18 13s bms in my battery pack?

[@donscott6431]

Dude! I love you. Bought all your books, but actually seeing the mechanics behind the building is priceless. I’m a novice w/LI batteries, but after a year of reading, watching and buying a spot welder and 95% pure nickel roll, I’m gonna attempt to build a replacement 48v, 10.5 ah battery for my smallest (grocery-getter) e-scooter.

[@TheLondonCyclist]

Bro, I've watched all of your videos for this. It's amazingly put together. I never understood the whole buckle strip placement, but now I do. One thing I'm getting my head around are the BMS wires , but I'm sure I'll get it after watching the same video a few times.

[@kylecensabella7069]

Thank you so much man. Now I can finally finish my build. I connected my b- directly to the controller and it didn’t work. Thanks to you I know now that the p- goes to the controller👍🏼

[@BrunoPOWEEER]

FANTASTIC VIDEO mate!!! You're the number #1 ebike educating dude..... LOVE watching your videos, reading your educational articles, your educational battery build kits... man... you rock!! Well done.. great job as usual =]

[@michaellink6960]

Connect the sense wires and the power wires BEFORE plugging in the sense cable to the BMS. The circuitry that the sense wires connect to contain MOSFETS which are static sensitive. It is also a good idea to use a static wrist strap when installing the BMS for the same reason.

[@martinhardy5772]

Hi. Great vid again. Just purchased you book and I'm very impressed. I would recommend this book to all. Keep up the good work.

[@farida7777777]

Thank you very much, was stuck for months with this. My inverter charge and discharge on the same positive and negative, thus -p and -c will use my inverters negative split into two to solder them into the bms. Thanks. GOD bless.

[@komodospider]

Micah thank you for sharing your knowledge with us, it made things a lot clearer for me

[@simengineering9183]

You are awesome! been searching videos trying to find a simple and straight to the point explanation, You nailed! Others should learn from you! Short and simple 🤘😃🤘 you just got a new subscriber.

[@johnnykelly8582]

I just want to thank you for making these videos. It really helped me a lot You are awesome.

[@pneumaticfx9897]

Love your videos man, always a go to when I'm building a battery. Thanks

[@pandaexpresso]

I'm an American modding an e-moto in China for fun and this is saving my life.

[@quentinrufin4025]

For those who wonder which connectors to use. After trying different type of connectors, I recommend XT60 or XT90. XT90-S is good for powerful batteries.

[@angellee713]

thanks for professional advice

[@CabrioDriving]

Super valuable video. You are great at teaching things. Calm, professional and telling all the details like nickel thickness for certain amps. Highly appreciated video series. Maybe you could record something newer for the knowledge and experience you have in 2021? :)

[@monstercolorfunco4391]

awesome guids, the ratings speak for themselves. I didn't see if you cover the heatsink of the BMS, and sometimes for higher power BMS the heatsink would melt the glue... all FETs and heatsinks benefit from capton/clearence/fets can melt nearby plastics/heatsink can be hot.

[@GrantSR]

So, Micah, I hope you've learned to use flux and a higher wattage, higher temperature soldering iron since this video. It's a great video other than the fact that all your connections are "cold." A hotter iron will heat the working area to the proper melting temp of the solder before that heat has a chance to migrate away to the batteries.

[@charleswalker8961]

Wow! Thanks for the excellent series and your easy going, very informative way of presenting the information. It is just what I needed to crest the learning curve! Questions: Do you believe these packs can be built without a traditional BMS? Also, who did the backround music in your "episode two"? Thanks, keep up the great work!

[@diegooolB]

Great video, and thanks! Quick question.... can I ignore the P- and just use it for charging the pack?

[@maxkodiak9591]

I thank you for your video its my license to understand the connections p- c- b- and finish my battery Thank you very much.

[@djmips]

I'd recommend using a liquid flux when soldering.

[@Convolutedtubules]

Soldering acid helps also.

[@svleez]

Thank you for sharing, it's a very cool and instructive series of videos. I'd like to know what is the best way to make a 20s24p battery pack for a e-moto I'm building. I know I need look for a 20s BMS, but should I weld the 24 batteries in parallel? Or would it be better to make 20s battery packs with, let's say 12 parallel cells, each one with a BMS, and then connect the battery packs into a larger battery pack. Thank you

[@JohnDoe-km7ch]

it tooks me 1 minute watching you video to get information i need. thank you.

[@mrd.808]

enjoying your YT videos. I do recommend redoing your older YT videos with the music turned down. Or make one with music and one without music. or maybe I will just hit the cc button. thanks, Boss, keep up the outstanding work!

[@Ibamba7]

Will 60/40 Electrical Rosin Core Solder AM31604 work fine to solder a battery pack and not melt fast? Melting temp is 374 Fahrenheit

[@ronzandroid]

Would the power on/off switch connect some where along the discharge? if so would it require a fuse with packs amp rated?

[@milodimich16]

You are the most honest person and amazing

[@ryansills509]

Do I have to connect my discharge connector(controller)? I want to leave the controller hooked up to the batteries on my ebike but I only want to connect the balance wires and main positive negative of the battery pack to my BMS system. I'll also obviously have the charger connections hooked up as well.

[@Ra-zor]

Dont like having the bms on the pack, after a bms failed on me i have it connected to the charger now instead and just plug the balance lead from the pack in to the bms, and the xt 60 from the pack in to the bms xt60 + and -. This way if the bms fails it does not kill the pack (has happened to me and discharged a parallel section of batteries to 0v, killing the cells). Use an in line 40a fuse to the speed controller as your protection.

[@gerarddupuis6033]

again enjoyed your video , just wondered if when you are soldering wires onto your nickel strips if you are using acid core, rosin core, or just plain solder?

[@herenow2895]

On this BMS, the sense wires are to be fixed to each cell + , but you solder them between the + and -- . If the BMS required that they were to be soldered on the -- end , where would they go ? In the same place ? As you fixed them in between the + and -- of the cells, what determined that they were fixed to the + ? Is it the direction of flow ?

[@Bowtie41]

Mike, If I build a LiFePO4 pack,does the little chips on top of each cell do they same as a BMS?

[@cubiq1]

Hi Micah, thanks for the video! How well does that 10S BMS balance the cells? There is some speculation online that the PCB is missing a dual-diode (if you look closely at the back cell 1 channel, you'll see the empty PCB pads). Have you noticed any issues?

[@LierreNarcissus]

Do you have a video on wiring the battery packs in parallel? To power a 72 or 96v system?

[@savvasberdos1828]

Thanks one more. You even show us how to solder nicely.. Is there any way we can check if the BMS has indeed a balancing function? And another question: Is it worth it to find BMSs with temperature sensor? Thanks.

[@Grind671]

How do I wire it to charge and discharge through a single connector?

[@wesleyoh4033]

May I know what is the real difference between a BMS with negative charge connected to C- and one BMS without the C-? Is either one better than the other or what is the real advantage?

[@W-H1U]

i watched a video were a guy put the discharge connector negative on the c- instead of P- and it still worked...i am so confused!

[@emreiris114]

It was so informative video But I still have one question that I cant find the answer yet ,lets suppose we have 3S3P battery pack do we have to connect cables between every individual cells or is there any other way to balance all cells at once?

[@frederickschulze8014]

The p- and c- ports on my bms are right next to each other and the metal contacts on the board actually touch. Does this imply that while I could connect two wires to it, I'm essentially using a shared c- and p- port? Based on this, it seems like it would be useless to add a second charge cable and instead just have a single discharge/charge connector.

[@agmendoza2830]

Hello, in the diagram on my BMS from Vruzend the P- is a blue wire, if you look (3:27) the C- is the blue wire.

[@sourovghosh]

Hi Micah, how one can increase the current rating of the BMS? As you probably have shown for the battery pack by welding extra nickel strip.

[@sameliezer63]

Hi, I'm trying to replace batteries of my booster board v1. I got the new batteries and like to understand what is the sequence of steps I need to follow to solder the balancing ends to avoid shorting and frying the BMS. I need to make 12SP1.Do I connect all the cells in series with the and then start to solder the pack to the bms from main '-' then the balancing end all the way to the main '+' ? Appreciate your help

[@immortalsofar5314]

Useful hint: Some of the cheaper BMSs (like I can afford) are *rated* for 50A but need the channels reinforcing when you go above 20 (at least they were honest). A layer or two of pre-tinned solar cell ribbon along the power lines in the board will add the extra carrying capacity you need relatively easily and for cheap. It's also really easy to cut into the right shape and size. How much current goes through the sense wires? Those I have are good enough for signals but not for power so I need to know whether or not they need replacing. Any reason you're soldering the negative wires all the way along an already conductive nickel strip?

[@TOMA-ny7gg]

hello can u please explain how to replace the battery and connected them on hp 9 cell battey thanks

[@mikelilley7136]

micah nice video i think i understand what to do but in a previous video you talked about putting 2 bms onto the battery pack in case one failed if so do you connect both identically and if one failed would the other seamlessly take over?

[@armanddivinagracia2922]

hi Micah, i really love watching you're videos, you explain everything so clearly. i just want to ask about choosing the right BMS for my battery pack. lets say if i'm going to build a 12v 14.4ah (panasonic tesla LDTSL 21700, 3.7 4800mah 10A max 35A) what would be the recommended BMS ampere for this build, will a 3S 25A do?... i'm also trying to find a video on your channel how to calculate the Amps when building a battery pack. because in my example,if i use the tesla battery with a rating of 10A each with a 3P connection would that total 30A and do i need a 30A BMS?

[@nealwoodburn7510]

Great Series man, I just have a few questions I have Prismatic cells, what would be the best way to connect a 36V battery pack with the prismatic cells, as I am building an E-Bike as well. I am also developing my own BMS, do you have any insight you could share regarding building your own?

[@mohammeduzair694]

hey micah , could you please make a video on building a 24v battery pack , thanking you .

[@ioanniskontos9439]

Hello, nice video! Thank you! I want to ask if the current i am looking for is the total amperes of battery or the amperes my circuit needs! Oh, and also what power supply do i need to connect to a bms? Thank you for your responce!

[@shaneweightman]

Great clearly explained video ,, thanks Shane uk

[@mappy1944]

Very good video. I just have 1 question. What kind/size of cable do you use to connect BMS B- to my batterypack?

[@mine0002]

if i want to build a 96v, 20ah battery, you indicated i would need a 96v bms. usinga 30s2p configuraiton. but could i use one bms with a 16-channel bms since there are two parallel batteries?

[@davidwehrcamp477]

I noticed in one of your posts you said you could parallel 2 BMS together to double your amperage would you be terminating all of the wiring on building a 20 S5P battery and I could only find 40 amp BMS for 20 S if I was to wire both would I terminate all 20 wires on each BMS identically I'm praying you can answer

[@VladMereuta]

Have you tested that specific 10s BMS featured in the video? I'm about to get one for a 10s4p 18650 pack and I could use some reassurance about that particular BMS. Does it correctly balance the cells, did you have any issues with it? Thanks a lot for your help.

[@ModifywithManoj]

What is the input voltage rating for 3s bms

[@danielelbaztm3706]

Want kind of charger i need to use for this

[@pedrohernandez1637]

Hey I just have a question hope you can answer it please. How can you let the BMS the voltage of each battery? What if I want to choose other type of battery every battery has different voltage. How I set up the voltage so it prevents from damaging the cells?

[@avicenadelcastillo988]

hello super cool videos , i have question where can i find 72v or 96v bms ?

[@brannenthompson9662]

How do you build a 52v battery as in your 48 vs 52v battery which is better, when you have to match the BMS ie 13s because you would need 14s?

[@9023850605]

Can we use hight rating current BMS on low rating current (ah) of 18650 battery pack.( Like I have 48 volt 21 ah (approx) battery and 13s , 35 amp current capacity BMS.

[@NateHarrisCreations]

Which one would you recommend for a 12v 4s prismatic setup in a car stereo setup? (CALB we 100ah ) charging will be 4 300 amp alternator

[@talfecher9231]

Hello, I have a question, If I have 2 controls working in parallel, does that mean that the total amps that my bms need should be more than the total amps of the two controls?

[@leonmellingen3633]

What about a 2 wire bms with only P- and B-? Should minus on charge connector go together with P minus on bms?

[@charlottegreen701]

is there a limit to the number of batteries in a parallel group? for instance would it be possible to make a battery pack of 3.7 v with 20 batteries, then connect 3 packs in series for a 12 volt pack?

[@innocenttech5678]

If we use first four wires(i.eB-,B1,B2,B3) of 36v bms...can we make and charge the a 12v battery.

[@szakbak]

are bms supposed get hot??mine gets real hot i am afraid to leave it plugged in??as it melts the hot glue??polarity is good seams to not work ass its drains the battery from 16.8volt to 13.5 volt thanks for your videos

[@karabetbidros3936]

Thank you for the video ,its realy nice but i am new on this cous i dont have the background study i would like to build my battry pack myself its 26v an 9 ah whats the best way to do this ? And one more thing how you know on this video where nummber 1 terminal is ? Ist always the negative terminal n 1?ans at the end positive ? Thank you.

[@Manrique1721]

Hello I have a query I am designing a bank of batteries for a 48v ebike and I have bought a bms of 13s 20A and when it is loading the cells a few LEDs are lit but not all the LEDs have been lit when the charger is already disconnected and not Load more and the other is when I am testing it and it exceeds 20A of the bms it disconnects the system, which recommends me. thank you very much.

[@pistacheuuuu]

hi, very nice work, i follow your advices and everything go right. It works! The only thing i'm not sure about is the foam. My english is too bad to understand evrything you say. Can you tell me, please, what kind of foam is it and where i can find it. thx

[@franzereyes2448]

Can i connect 4 12v BMS in series and use 60V charger?

[@patprop74]

so the discharge port is basically the power out that goes to the bike's controller?

[@denislindesay3731]

Excellent video's, thanks. I am replacing a BMS on my 36v bike battery pack and I have got the same BMS you show in the video. You don't mention wiring a switch. Are they the two connections on the left hand side of the 10 wire connector? If this is correct, shouldn't these connectors be bridged if no switch is used. The existing battery pack switch had small gauge wires to connectors on the BMS.

[@Max_Weight]

I got a question, I have 4 cells, 24 volts and 18 amp but I just found a bms that support 4,5,6,7,8,9,10 cells should I get that one, I can't find any that support 4 cells 24 volts and 18 amp.

[@Alksbbch]

I f I conect to P- power and charging cable, what when be wrong, then will no be overcharge protection?

[@andyhawwa6604]

If I have a b+ connection on the original bms i have can I use a bms that doesn't have a b+?

[@kylieomsin904]

i just want to ask what kind and size of wire to be use when wiring those 18650's

[@franciscosanchez9406]

What are the difference between using a BMS vs a TP4056 Lithium Battery Charger Module Charging Board With Protection Dual Functions

[@saravananneelakantan692]

Hi, how to select BMS board and what does S stand for?

[@brucesweatmaniii6030]

Have a bms that 16s but it only has B- and P- only? it has no C- cord or points at all/ Question how would you wire it up? Thanks for any help!

[@andrewblade8857]

If you use a bms with to high of amps , does it mess up your controller? Please respond I need help with my battery

[@myozone]

There seems to be a lot of different types of BMS's (charge and discharge) , could you explain this and how they work - I have an electronics background

[@ggss1176]

thanks very helpful and informative

[@some1544]

Even though I'm using an bms, my controller seems to draw power just from a single cell group and managed to undervolt it completely.. I'm quite concerned and especially don't understand how this could happen since the bike was just standing at home

[@akash-vr9xm]

If I have 58.8v, 30ah lithium ion battery pack with 14s bms what should be my charging voltage and current for my bms

[@sherrylewis8780]

Thank you! the most important info was right away

[@rambushrami6471]

Hi! I have bought a bms and it doesn't have a C- wire. In stead, there are 2 P- wires and the manual says that I should connect the P- wires to the charger and the controller. Pls help.

[@whatthefunction9140]

The power wall people dont use a bms, why should they or why do you need to when they dont need to?

[@zarpjj]

I plan to build a battery pack with 18650 cells, one 3S5P, to power my LED lamp torch and I will add one BMS on my pack. How do you know when the pack is fully charged when I use one BMS with my pack? I also have TP4056 charger to charge 18650 cells individually; when the cell is fully charged, the LED "CHARGED" turn on. Do you know if some BMS will display the status of the pack "charged" ? Thank you in advance and thank you very much for your video, very helpfull. Jean-Jacques

[@ChaplainDaveSparks]

I'm a bit confused as to what does what. I understand that lithium batteries need constant current / constant voltage charging. When you use a BMS, do you also need a "lithium charger" to do that, or is that functionality contained in the BMS, so that a simple regulated power supply + BMS is sufficient?

[@MrGiodude17]

Hi I have a massive issue I have 2 newish 60v 20ah 18650 battery pack can u just help me by looking to see if the rust / water damage is effecting the battery cells or it’s the bms Becuase I accidently plug the brake in the charge via controller

[@cliffthompson4149]

Hey man I really appreciate your information and making this video but I have a little problem I'm getting power from my battery pack but it is not delivering to my bike. I have two other batteries and they work great and I've troubleshot everything. Do you have any suggestions or what am I look for?

[@petertothRC-FPV]

nice videos.i was hoping i could salvage 2, 48v 6ah bottle style batteries.i dont see any videos with them opened up.i used the throttle to much when i first installed 1000w the front wheel kit.i use a 12ah bat.now and have a 6ah for backup.after i ruined the 2 batteries i mostly use pedal assist so to manage and save my batteries.

[@jamiemcelhiney4759]

Do you need to solder the B- and the B+ to each spot in between all cells ? Or can you just do on one end of the nickel strip?

[@XG4bro17TM]

i have a question can i connect to the bms batteries with the same voltage but different current like one of 500mah and one of 2000mah??

[@raven_fpv]

The BMS I am using only has a B- and P- which I have connected to a XT90 connector. What type of charger do I need?

[@atorresmiguez]

Hello, thanks for your videos, they are very useful. I want to put a switch in the box of my 10s battery pack, can you give me any advice? sorry for my english and thanks in advance.

[@MaxGoddur]

Please help. Just completed my 14s4p battery pack my problem the BMS 14 lead wire harness is now too short to reach the cells monitoring voltage. Can you recommend the tools and parts purchase for building your own wire harness? Or better yet a 14 lead harness with leads at least 12 inches long.

[@randygrindle5121]

i was actully wondering would it be ok to hook 2 48 volt battier packs in series to a 3000 watt ebike kit thats supposed to have about 98 volt pack

[@shivshankarmaurya4597]

any problem in working power pack,please upload image how connect it

[@724horndawg]

I'm trying to replace Littolala 50a BMS and it says wire neg from charge connector to B- and the LOAD NEG to B- also. What is the load negative wire????