The *ULTIMATE* BMS Guide

[@diydad5067]

Just a word of caution. Not sure if it was mentioned in the video but just beware of over-discharging your cells, so needless to say, keep an eye on your voltage. Bypassing the BMS will disable your low voltage cutoff protection.

[@juicyboi2923]

So your electric skateboard will just ride till it breaks?

[@jean-luclortie5001]

Good info

[@dannynapoli2169]

@@juicyboi2923 Yes it will. Once the batteries are discharged beyond a healthy 2.6v per cell, they won't retain the same charging capacity anymore.

[@MILLERS066]

Man am I thankful I just stumbled upon this video. I wired up my 40a BMS today and wired P- I’ll take that off. Makes total sense now.

[@LeeWright]

No worries bro, glad it helped you!

[@danobonano1315]

@@LeeWright I'm rebuilding a ninebot ptr battery pack, its 2 packs 15s2p each pack, factory was 30 amp bms can I replace them with 60 amp bms?

[@WORLD-OF-MERLIN]

Where can I purchase quality BMS’s?

[@adeydawe645]

Hey Lee, from someone who's very new to the Esk8 scene, I find your videos really educational as I really want to build my own mountain board. Hopefully once I've watch all of these vids I might be able to do so haha. Please continue to keep up these videos your doing a great job for the esk8 community. Well done 👍

[@LeeWright]

Hey brother! Thank you very much! I'm so glad you are learning some stuff! I'll continue as messages like this get me so hyped!

[@itsmedant]

Man I absolutely love the music in the background! Keep up the awesome videos Lee!

[@jonathanbayardo6732]

My guy I'm just starting a serious college project regarding battery packs and you literally just helped me to solve all my doubts about what to do coming up next with BMS connections. Thanks a lot Lee you're amazing!

[@aaronstanley6914]

Now that you learned some more does this video still hold up?

[@nickk1502]

As an American I heard “30” on those balance wires. Took me a good 2 minutes to realize you actually said “13”...😑. Great video man! Super helpful for my build.

[@matzedias]

Your videos always come perfectly in time, so i don't have to annoy you asking how to xD

[@LeeWright]

Hehe! Glad you will find this useful@

[@FAB1150]

Thanks! Assembled my first battery with this guide, works perfectly!

[@LeeWright]

Well done brother! I'm really happy that this helped!

[@greatdane3343]

Excellent explanation thanks mate. I have been trying to understand the discharge side of BMS fo high current discharge applications for a long time and found endlessly conflicting info on the net. The info on bypassing BMS discharge control on high current draw applications was the missing piece of my puzzle. Legend!

[@explosivegardenreboot]

im new to this, have some good electrical knowledge but as i say im fairly new this one. just got my first bms, nickel strips and spacer system for a 36v ebike battery for use on my schwinn stingray chopper. gonna take my time on this build as i want to do it right. currently get about 12 miles from the bike based on a 36v brushless 500w hub. plenty of torque for acceleration up to 18mph. subed to ur channel and realy enjoy the videos. great knowledge

[@LeeWright]

Sounds like a great build dude!

[@lhuff13]

Best BMS video on KZbin, nice 👍

[@LeeWright]

Thank you!

[@_nske]

Fantastic video mate -admirable attention to detail! I normally don't use Patreon but you're a top guy making top content, so I had to. I am not going to attempt wiring a BMS or making a battery pack myself, I just enjoyed understanding the logic/procedure/practices and filling some blanks. But what's most important is that you help educate/bring new DIY builders to the scene, keep up the great work!

[@LeeWright]

Hey man! That's awesome! Thank you for helping me out! In return you are now getting behind the scenes access, hope you will enjoy being part of the patreon crew! I just want to share knowledge and help people understand how to do this crazy esk8 building stuff - knowledge should be shared not hoarded.

[@simonchurchley8088]

Pretty handy video with a lot of gold nuggets of info there. Your batteries are a work of art. I will be after some improvements to my battery and BMS in the Icarus when the right VESCs come along.

[@LeeWright]

Thank you simon!

[@redreefbud]

Thanks 😁 I just ordered one of your smart BMS. Molicel p42, 12s. For my kaly deck and enclosure. It had trouble finding a Daly. Was watching this video and heard you say you had one 😁 thanks again and have a great day. Esk8 Freedom. Keep up the good work

[@LeeWright]

No worries dude! Will be in the mail tomorrow!

[@redreefbud]

@@LeeWright awesome thanks 😁 hey you wouldn't happen to know where I could get one of those 12s4p flexible PCB from, would you? I know direlect robot supplies used to have them but all gone and not much coming up in Google search. Maybe some of those 4p PCB would help me out 😉 I ordered the flipsky portable spot welder. Will be my first time welding batteries together. I have done a couple buss bar packs though 😉

[@redreefbud]

Arrived today 😁 thank you very much 😁 super speedy. Only piece I'm waiting on is the flipsky portable spot welder. Maybe tomorrow. Thanks again and keep up the good work

[@jvall08]

Great vid mate! Had an issue with my battery upgrade on my Evolve GT and decided to replace the ESC and BMS with new stuff. Was quite boggled when it came to picking a BMS. Went with a 40a smart BMS(looks similar to yours) but didn't realise I didn't have to use for discharge, only had the stock BMS to go off and didn't have a clue. So the original is actually wired for discharge then I guess.. The charge only seems so much more simple. 🤔 Thanks for all the info. It all makes alot more sense now.

[@LeeWright]

You are most welcome mate!

[@johnboy4809]

Just found your channel, really like your approach to building batteries and putting extra thought into making it as safe as possible. I'm more ebike as never been able to balance on a skateboard but have subscribed to help improve my own battery building. oh and keep the chilled background music

[@LeeWright]

Hey John, that's super cool of you to say. I think it's important to make them as safe as possible, bloody bombs haha

[@hansdampf1968]

Good advice with the smart BMS and the fish, kepton tape! Keep up the great work. Thx a lot

[@jwagner217837]

What a GREAT Video!! Exactly what I was looking for. Thank you so much!

[@roboticsguyy]

Is it safe to discharge straight from the battery? You could over discharge the battery right?

[@movation]

Great work lad perfect battery build but you extended the balance wires off camera this is a trick for new players may not be aware of. Only thing I would have done different would be add a inline fuse to charging port. But not required. 5 star build mate.

[@LeeWright]

Yup! I fuse all my charge ports! I put the fuse on the board end of the loom not the battery. Ta bud, hope this video is useful to people venturing into battery building

[@martinem78]

Great video brother. Appreciate the effort and it was super informational. Gonna use it for my build.

[@hamzamardini6156]

bloopers is my fav part but im going to buy that bms :) (12s)

[@LeeWright]

Awesome! Yeah the bloopers is funny! 😄

[@modestasbitinas7369]

Thanks mate, I just got exactly what I need for the charging stuff.

[@TimWoodVlog]

Getting super nerdy! I'm loving the education 👍

[@LeeWright]

Thanks Tim! Super nerdy! 🤓

[@chriswf]

I'm curious how much power the bluetooth module constantly draws. Like a BMS always pulls a tiny bit of current, right? That's why you have to recharge unused battery packs after several months, right? So how fast does the bluetooth drain the batteries?

[@Flatout56-o8k]

I’m building a 6s 22.2v 30ah lipo battery for my board would I have to buy a 22.2v or could I buy a 25v bms and also it’s a 30ah so would I have to buy a 30ah bms?! Please help!!

[@paulridgway3364]

Great Video! You mentioned that locations of temperature sensors is important, but didnt show them. Where are those places on the battery?

[@LeeWright]

Only that they need to be spread apart and need to be in close contact with the cells

[@ksrnate]

Hey dude great video! Can I ask you something, I've built a 13s pack for a scooter and the 2 BMS I try on discharge mode for some reason are 11v less than the battery?? So the battery is 53v and the BMS discharge is 42v?? That's same with 2 BMS now. You have any idea why that is?? It's wired 100% right. Hope you reply. Thanks 👍

[@LeeWright]

Hmmmmmmmm, I don’t know. I’ve heard about this before but never experienced it myself. I have no idea I’m sorry mate

[@ksrnate]

@@LeeWright No worries thanks for getting back to me 👍

[@kompadoodle]

Aw thanks dude I couldn't find anywhere how to install this game!! I just cleared Volcanic!

[@negaopiroca2766]

Fantastic Lee, really nice details. Why do you cut the heat shrink at the end leaving the BMS a bit exposed? Also, how do you calculate how many nickel strips you put on? Also, when you connect two groups laterally, are you bending the nickel strips? Thanks

[@LeeWright]

The BMS I freed as the heat shrink was putting too much pressure on it. It won’t move because of the wiring. Batteries are a whole other topic and I’ll go over that in detail very soon. But yes, bent nickel between the groups across the pack and braid along the length of the pack to keep some flex

[@biltre21]

@@LeeWright That would be very useful to know! I use to build my batteries like two identical halves and I connect them with a cable. Your approach is new and interesting for me, maybe only disadvantage is red cable must have to travel from the other far side. Wondering about what this "braid" could be, never heard about it...

[@negaopiroca2766]

@@LeeWright oh I see. Will you take any measure to prevent water ingress on it?

[@LeeWright]

@@negaopiroca2766 no mate, theres only so much you can do with it. I Leave that to the customer

[@adventureswithsteve2981]

@@biltre21 i agree with you regarding the positive wire, remedy is to put the BMS at the opposite end and rotate

[@ivanmcnamee5656]

Love the video. I have a few dead cells in my battery pack. Is it possible to replace the dead ones. Without causing others issues with the hole pack.

[@Bassplayingypsy]

Lee. You the man. I learned a lot about BMS seems I thought I knew. Lol. Almost as funny as you video ending. I'll be getting with you about a 12s battery pack built by you. Blind I am. It would be very dangerous if I were to try and build a big battery, or a battery of any sort for that matter. Hope you'd be intrested in building one for sale. Keep them vids coming. Good stuff.

[@LeeWright]

Hey bro you are welcome! Yes we build batteries for sale no probs

[@Bassplayingypsy]

@@LeeWright thank you bro. Now to get my money right. These times has my money all funny. Let me know a price for 12s5p 21700 cell battery pack. It's going on a drop down board but it's 41.5 inch long at 10 inch wide. Should be enough room to accommodate that big ol battery pack. Oh. Might need a vesc too. Again, thank you Lee. Safe riding mon frère.

[@MrRailcraft]

Quick tip. When you put some timecode into the description, you'll get an awesome feature. 😉

[@LeeWright]

The timecodes are in the description bro!

[@adventureswithsteve2981]

@@LeeWright time codes on videos really put them on the next level , nice 1

[@whitefeatherslinger8194]

Good vid ,well explained 👍,(ive done exactly what youve done but when connecting b- to the bms the bms blew!very annoying anyway the only thing i can think of was the last bms's harness had the black lead looped into the next port on the harness and then continued as normal,would that have been why the bms blew or any other suggestions would be greatful)keep in mind i double checked and taped down properly before harness or main b- was connected 👍

[@m.frohlich2651]

Nice explanation, i learned things 👌 Thanks man 👨

[@TheEVside]

Great video mate, really interesting (although my wife had to translate the electronics parts) :) , battery work really good. And loved the bloopers :)

[@LeeWright]

Hahaha! Brilliant. Is the wife an electronics eng then?

[@TheEVside]

Yeah she’s been building printer circuit boards as a job for 20 odd years

[@TheEVside]

Printed

[@randysonnicksen9475]

Hi Lee, I just bought a BMS from LLT Power (same mfgr as the one you demonstrated). I can't find a wiring diagram or manual for this unit. It's a 14S 100A Discharge and Charge unit with BlueTooth, and a couple temperature sensors. There is a B- terminal , and a C- terminal (no P- terminal). How do I connect this to my charger and to my load? It also has a two conductor JST connector with black and red wires next to the balance voltage connector, but I have no idea what this is for. The silk-screen on the board by this connector says "SW". (switch?) Have you seen one of these before? Can you point me to a manual or diagram, or give instructions on connecting this to my battery, charger, and ESC? Thanks!

[@wes8732]

Nicely done sir. I appreciate emphasis on clean safe work area. Lions are nothing to play with carelessly. One thing with these BMS builder/maker/diy videos ? Limited to zero mention of BMS WIRING SEQUENCE. I.E. 'connect negative & then sequentially wire individual cells', or 'wire negative lead, then positive lead and then connect cell bms lines, or it doesn't matter, wire it up with correct polarity & bms lines. Perhaps it's not relevant if no damage can occur from wiring from either pole & all cell lines in between. I have just not seen any mention of 'specific' BMS wiring sequence. Though I highly rate this video as quality information. Thanks for this video! Liked n sub'd

[@rodscott7232]

you teach us so much, Thank U Lee

[@johankumpula]

I am building a 4S pack for use in my Tesla, the pack will sit in parallel with the stock battery, but will a BMS be able to let the charge current from the DC-DC converter through or do I have to solve this another way?

[@marktaylor7619]

Very well done. Awesome editing or the video!

[@mrkeopele]

VERY INFORMATIVE thank you, i do have a question: can i setup the cutoff voltage of the BMS to anything i want with a smart bms and the app? I want to try and use my battery cells down to 2.8 before they shut off discharge flow. I watch my parameters as i ride my ebikes so I would like to see if i get more range and same life span with a lower shut off voltage.

[@Konstantin_Kaiser]

What did you use to connect the packs together, making it flexible. It didn't look like a nickel strip

[@taruix603x5]

Can you connect in parallel the BMS to get more current?

[@AngleGroupProductions]

Can you do a video or quick topic on fuses and why one would use it and why we shouldn't use it?

[@edmacneel547]

Hi Lee, where do you recommend placing the temperature sensors. Does the phone app allow for alarming a high temperature? Thanks, Ed

[@edo7611]

I love the details. Thanks 🤘

[@DavitoDaveeni]

is it possible to connect 4 bms's in series for a high voltage pack ?

[@d.d8-vr926]

I've got a summerboard V2 Battery. It's refusing to charge, but I have about 80% left on the battery and it will still run my board (got a free replacement - Aaron mentioned about a problem resistor on the earlier V2 batteries?). I'm getting the red blinker of death on the battery, but I was wondering. Would it be a BMS problem or I have a bad cell? Annoying, the bloody thing is actually well made and I've only managed to get it out of the casing and do some simple voltage checks.. Would sticking a different BMS work? or would it be easier to just rebuild and try and fit it into the current battery enclosure?

[@timothyodum4994]

Hey Lee, building a 10s 36v 15ah pack seen plenty of videos of how to wire the bms but what do you use to power them to charge? I have a Li-ion battery charger that outputs 42v 1.5ah would that do it?

[@1112223333111]

I have a 48v 26ah pack and it had imbalace section. I got it charging then the green light come on but with I unplug the charger it falls to 38V. I plug the charger back in it shoots to 54 and stays green. I tore the battery pack open and unplugged the bms and jumper the charger straight to the battery bypassing the bms and still same result. does the 18650 have a fuse in it? it floats 54v but no current. thanks!

[@JAYRAY00]

Some or all BMS boards are listed as 3s, 4s etc. Do i need to get one that matches my series? Can i use a 4s for a 3s setup? If so, which balance wire do i omit? Which brands are good, where to buy reputable brands, what to look for in a bad/good bms. If i want to be able to use the battery and charge it at the same time, is that possible? Do i need a specific bms for that?

[@longle7603]

Hey Lee, Great Video Currently building a battery pack. (10S3P 36v) 1.) What keeps this battery from over discharging when the discharge bypasses the BMS? 2.) when choosing the BMS I look at the Cell's discharge rate (which in my case is 5C) The capacity is 2000mah. So I think that means 5*2,000=10,000mah, 10,000mah/1,000=10A. I should get a BMS that has max discharge of 10A? What would happen if I put like a 15A?

[@LeeWright]

Great questions. If you don’t use a discharge BMS you must have another means of monitoring and/or controlling the discharge. Maybe that’s an ESC that will cut power at a certain voltage, or a voltage meter you keep an eye on. Yes if the battery can discharge at 10A then a 10 or 15A BMS will be fine, a little head room won’t hurt

[@longle7603]

@@LeeWright What would happen if you pull more more than the discharge C rate? Like in my example if the battery is only 5C, Would putting a 15A damage the battery if the load tries to pull more than 10? Just curious, still learning.

[@LeeWright]

@@longle7603 in reality the internal resistance of the battery would rise as it gets hot and restrict the current to below that, however its dangerous to get batteries hot like that and so obviously it’s not recommended to pull more A than the battery is rated for

[@longle7603]

@@LeeWright Ah, thanks. Sorry for my noob questions. Still learning and trying to learn as much as I can before i set something on fire.

[@amerkhafagiable]

Great vidro bro.can i use 14s bms to 13s battery pack and how ?

[@lorenznoichl3252]

great video, great music

[@abramzacharias1]

This video is most helpful from all the other videos I watched. I'm trying to build my first battery pack with 18650 cells 13s 3p with a lifepo4 bms (charge only). It's a 16s bms, and I believe it puts out a slightly less voltage. And I have a 2a charger for it. Would that still work?

[@EduardoWieser]

Hey there. Great video, I am attempting to build a 7s charger and got a load of different bms models. The one I am currently testing has no bypass so what I did is split the P- line in 2 and add a switch to change between the Charger- and the Load-. This is essencially the same as the bypass configuration right? Also, if all I have is a voltage dc supply, to what voltage should I set to charge a pack of 7s lipos? 29.4V would be their 100% voltage, but can this present any danger? Should I set to a lower value?

[@jamesmason7124]

Thank you for sharing your ideas with us I’m about to start looking for a 4s BMS but I need at least 300 amps and Bluetooth what would you recommend keep up the good work and stay safe

[@SparkyJames]

Thanks, Good video very informative!! ....I’m guessing you have a G7x camera , I had one and that auto focus drove me nuts, if you haven’t replaced it already you can actually program in the part you are trying to focus on as a face to make it focus quicker or just use an iPhone

[@kamillapaj87]

Does it matter what kind of bms is used when using regen braking? I hawe bms with p - port, I want to replace it with common port smart bms(that is what I was able to find in this size and already ordered it, the question about regen came after fact :P) so the question is, what does control the regen so the battery does not explode, is it motor controller or bms? And does the kind and brand of bms matter when considering the use of regen braking?

[@danmortimer8608]

Thanks man. Are you able to answer some questions about my battery pack? I am trying to fix a couple of packs that have drawn too much current through their BMS systems.

[@MJamMan]

I just bought a lifepo4 golf cart battery and a 10amp lithium charger from china Alibaba with a custom metal box to fit my existing frame for a simple drop in installation. It's a 36 volt 100ah with 1 Bluetooth BMS system. They told me not to series 3 12 volt batteries together as it's not stable? My only concern is explosion. Any thoughts on 3 12 volts in series with 3 BMS vrs1 36 volt and a single BMS?

[@iamthepolice]

I'm upgrading my solar flood light - powered by X2 18650 batteries should I put a bms in or not?? I'm new to all this .... Absolute beginner

[@muhammadmuneeb3963]

Sir can we use 4s bms with 3s battery pack...?

[@ASeSkater]

Great Vid Lee. Feel like im in esk8 school

[@user-pwfus]

Can you use any bms with the same cell count if it the same type of system? Also if it is the same type of system and cell count can you just use the existing wiring and cut and join the wires using your new bms harness?

[@davidbisciotti7424]

When looking to select a BMS, how is the current rating selected? Do you select on that can handle the 1C rating of the battery pack or maximum C rating? (ex. 5C)

[@LeeWright]

Good question. It depends on several things. If you are using a BMS with the discharge path through the BMS then you have to consider how much the load will pull and if the battery can supply that. If you know the load will pull 200A and you have a 300A continuous battery then maybe selecting a 250A discharge BMS would be prudent

[@MonkeyUK.]

Can u please help me your video was absolutely amazing and I now understand my BMS a lot better. But can I asks u what is the black wire that is sort of a loop it’s the only way I can put it. It’s comes from the BMS and god back to the BMS but loops on it self. Can u help me in what this duz please

[@sdcoffeeroaster]

I'm a emtn biker using a hoverboard battery as a range extender on my Focus Jam2 ebike. I'm also looking into building some packs, learning as much as I can before I try that and have a quick BMS question. If you use the BMS in bypass mode, what keeps the bike from running down the cells too far? Must be the ebike controller preventing that because my hoverboard batteries are in bypass mode. In that case is their any advantage to running the discharge thru the BMS? If sized right won't it prevent an ebike from pulling more current from the cells than is safe preventing overheating? Again I'm guessing the ebike controller does that too. In my case I'm making an ultra light 10s1p from tesla 15A 21700's. Obviously I don't want to pull too much current from these and ECO mode will help prevent that but I'm wondering if selecting a 15A BMS and using it discharge mode. thanks, love your videos. I've learned a lot.

[@LeeWright]

Awesome stuff bro! Yes for a bike you want to run in bypass for sure. The reason why we don't run in bypass on an esk8 is there are no mechanical brakes. If that BMS cuts the power you lose all braking. For an elite you don't need to worry about that so I would run discharge. Good luck and you are welcome bro, glad I could help!

[@MyWorldAsDylan]

Super informative vid bro 🙌👌🤙

[@doncodman913]

Hi Lee. Hope you might be able to help me ... i have a copy Xiomi 365 scooter . I am sure the massive bms board is fooked. Do bms boards connect to its controller via bluetooth do you think ? I can the scooter to run for a few seconds then get the error message of no communication to battery . Some beeps and flashes counting out the error code. Im glad ive found someone in UK ,you, that might be able to supply some parts and advice for my future projects. hope to hear from you Don Codman

[@django1364]

Excellent videos would you charge to build a replacement pack for the Ninebot E+ and to ship to the Caribbean?

[@scepticalbudha2553]

Hi. Very educational video. Thanks. Im trying to put together a battery pack for my motorcycle with each cell 2.1 amps. 5 rows in parallel and three cells in series to give 12.6 V fully charged at 10.5A. As Im a newbie, I do not know which BMS I should use and how to connect. your assistance if possible will be highly appreciated.

[@JaydLawrence]

Coming from the drone hobby, the part that is crazy to me, is the tiny wires coming from the charging port to the battery and BMS. What current do these types of batteries usually charge at? Even at a 1 or lower C rating, with 4 or more cells in parallel, that is going to be 10+ amps of charge, does that bore require thicker wires? This is not a criticism, I have seen everyone do it, I am just trying to understand why?

[@JaydLawrence]

Ok, I quickly looked up some chargers and it looks like they are mostly under about 6A, so I guess that makes sense. But why is the charge current so low? A 4Ah battery at a safe 0.5C charge is already 2A. So a 5P could charge at 10A!

[@locatejohn]

Great video. You you make a video where you start from the beginning on how pack the 4P, spot weld, and daisy chain the cells?

[@LeeWright]

I have something similar on my channel already bro 👍

[@harleyjordan7668]

Hey, great video. I am building a portable computer monitor and am struggling to get a system with both BMS and state of charge, so my users can see their battery level on led’s or something. Do your skate boards have a battery level indicator? Any advice for how to wire it up?

[@hishammustafa880]

Hi please what is the difference between P- and B- in BMS and does lithium battery packs need special chargers or any smart charger can work with them ? Thanks

[@sr8shoota]

I have not built a battery but I starting to get all the equipment and supplies. What I and wondering is if I can get a bms that can do 14s and the in the future I can upgrade it to a higher 16s or hight 8f 8 want to upgrade my motor?

[@andyb7754]

Lee, interesting video but next time have the camera pointed more at the table and battery pack instead of your face (just to see more of what's going on). Also, when you extend wires, stagger the splices. It helps with narrowing the width of the harness and possible shorting if the heat shrink happens to split (yes, I can see that they're taped down). Thank you for the video.

[@golfernst]

You said that the charging wire is 14 gauge. What about the positive wire going to the skateboard? Would be nice to know.

[@johndecowski9352]

What do you use for a charger. I'm building a 10s100p golf cart battery. Also do you just charge it through the pack pos?

[@javieruriel]

what are the considerations taking into account when we trying to pick the right bms for our battery?

[@LeeWright]

What S count your battery is, whether you are going to run bypass or not and what your charge current will be

[@KetansaCreatesArt]

Nice flat battery design. Good tutirial. They say trimming the balance leads will send uneven charge to the cells due to resistance difference. Does it really affect?

[@Skajlajnm]

no, it does not, these resistance values are negligible

[@kaylor87]

Great video! I have built a few packs myself so far and already know most of the basics, but stayed and watched the whole video for any new tips and tricks you might show me along the way :) Thank you! I do have one question though, which is why I ended up here in the first place... When shopping around and looking at the specs of a BMS, they always have a 'Max Amperage' rating. However, unlike some other types of devices, nowhere in the BMS specs does it list any sort of "Peak" or "Surge" power rating. Why is that? Is that maybe because the BMS acts more like a switch, and the moment you exceed it's Max Amperage rating, it just shuts off? There is no rating for Peak or Surge power, because that's not how they work?

[@LeeWright]

Correct bro. The BMS will indeed shut off if you exceed the max rating. The rating should be considered the max you can pull, I just dont discharge through the BMS so never had any issues!

[@kaylor87]

@@LeeWright Perfect, thanks so much man!!

[@PeterOrrick]

Can I connect the battery directly to the hover board, bypassing the BMS?

[@barkybarker2592]

I have a 48v ebike that isn't charging through the plug. I'm getting voltage out of the charger but the charger light doesn't turn red. I was able to charge by sending 54v thru the bike socket but not thru the charging plug. All wires are intact. Bad BMS?

[@aleszverca]

Hey thanks for this video, just what I was looking for. I am a newbie at battery building, but have electrical education background if I am right this is a 12S5P pack you have here right? Do you maybe know what kind of BMS is built into generic factory built Chinese battery packs I have a 13S4P (Ownboard Zeus) pack and had a power cutout mid acceleration which catapulted me of the board...and was wondering if the BMS was the quality mf....as it definitely wasn't the road or me... I am asking because I want to build another cruiser board with a 13S3P pack and want to choose a BMS that is a good choice between size/reliability.

[@adventureswithsteve2981]

Cheers for the video Lee. Can you provide a size and link for the blue battery heatshrink please.

[@chrisgraham7031]

When choosing a BMS, how do I figure how many amps I will need in a BMS? I am going to try a 20s 15p. 18650's are rated at 30 amps each. Motor is 10kw, controller draws 700amps peak and 280 nominal. Was looking at getting a smart bms but want to make sure I'm getting what I need for the application. Thanks

[@LeeWright]

Depends on if you want to use the BMS for discharge. I personally don’t so it’s irrelevant. I discharge straight from the battery. If you want to use a discharge BMS, the figure out what you want your maximum battery current you want to the motor controller and spec a BMS for that

[@chrisgraham7031]

So can you use any bms without discharge? I purchased an ant 400amp bms that has the bluetooth feature. Just trying to figure out if it will be fine for this setup. Thanks for the reply by the way. New at all this stuff and still learning.

[@jeffsit_davidli.333]

Hi Lee, when the battery pack is not on a load (not connecting to any appliance or device) or even charging, will the BMS be still working automatically to balance the cells ? the cells will discharge themselves over time, not sure if the BMS still detect the pack and start balancing according to the cell parameter. Thanks !

[@MrBobWareham]

I have just joined your channel not because I skateboard but I am interested in the battery side of the system, looking at the video I see you make battery packs so do you make packs for customers I have a disability cart with two 20 amp batteries in series giving 24 volts and want to update to Lipo cells so how many cells would that be, please?

[@LeeWright]

Welcome! 7S would be 25.2... lithium operates at different voltages to lead acid and you would need to look Into a DC-DC converter

[@zamazakati]

Hello! Im missing the calculations for what BMS to take, Ampere etc.

[@milordas]

ok, if were bypassing discharge with bms, what is prety wise, because discharge is manageable with controller, what amperage should be used of bms in, lets say 16p7s pack of Samsung 50E 21700 batteries?

[@LeeWright]

If you are only using the BMS to charge then you can charge up to 18A dude, whatever you find the best really! You can easily charge a big pack like that at say 15A or 4A (it will just take longer)

[@ShanakaAbeywickrama]

Great video. Question - will that BMS also balance charge?

[@africans1968]

Hi Lee, can you do the bypass with common port BMS? Thanks

[@LeeWright]

Good question. Yes - just use the P- as your charge port negative and charge port positive to battery positive as usual.

[@africans1968]

@@LeeWright great!

[@arrowho]

What is the maximum current of the BMS you are using now.

[@LeeWright]

20A, but it is bypassed for discharge so doesnt matter

[@nathanmaybrey6930]

This is such a helpful video! I'm looking to build my first battery pack (10s2p) with 21700 cells. Are there any other considerations which are needed when using these cells in terms of a BMS? Thanks!

[@sed6]

If you bypass the BMS for discharge won't you lose the low voltage protection? What's the advantage of bypassing it?

[@LeeWright]

Hey bro, you lose all discharge protection if you bypass. You still get under volt protection on a per cell basis. Bypassing offers several advantages. 1 - you can run a tiny BMS, high discharge BMS are massive, 2 - you don’t have the BMS in line between battery and VESC. We cover this on the video

[@camerongordon2378]

Where do you get the huge battery heat shrink wrap from and what size would be needed for a 12s 7p mountain board pack