How to Build a DIY 10s4p 21700 Electric Skateboard Battery (Tutorial)

[@scornman]

Just a bit confused why you used a red and black wire both going to the same joints. What is the thinking behind that? Could not a single neutral colour wire be a better choice?

[@RBEMotion]

Haha someone else asked about this too. It's not uncommon practice in the battery builder community. It's literally only so I use both colors of wire evenly. I don't buy a lot, so it's important for me to use them relatively evenly.

[@duh7048]

Clear wrap is both nice looking & I think it helps with maintenance. My friend has a board that is down because of a battery failure but it’s under warranty so there’s no cutting the pack open. He tested it & there are cells down but we figure it’s most likely a broken link. It would be nice to see all the way through & have a better idea. I think more companies should be transparent(pun intended)! Har har

[@RBEMotion]

Haha totally agree, I like clear shrink wrap too. Every time I see blue or black it just makes me wonder what it looks like inside.

[@scoty7392]

Nice build but I kept waiting for the main leads to touch when you were applying the heatshrink!😂

[@RBEMotion]

Lol that would be awful, I should probably have taped over one of them

[@jamo9000]

Great Video - Whats the clear tape with lines in called that you've wrapped around the fish paper on each series group ?

[@RBEMotion]

Thanks mate! The clear tape is typically referred to as fiber tape or reinforced packing tape.

[@MoAvW]

Great tutorial! If I may, one advise, try to keep any metals away from the pack. I've noticed you were a bit close with the tin wire to the pack positive soldering the negative.

[@RBEMotion]

Yep, definitely something to keep an eye out for. You only short solder across a battery one time lol

[@matteos.6712]

Loved the video! And quite cool the clear wrap, good work mate!

[@RBEMotion]

Thanks! Glad you enjoyed, I love how it came out as well.

[@gatishiphoshoko6529]

proper battery pack build well done

[@RBEMotion]

Thank you man!

[@kitmarshall4084]

I noticed that you’re using 10g wire to bridge the P group, is it bad to spot weld a nickel strip instead? Looking to make a 12s1p pack… do they sell U-shape nickel strip that runs to the top and down to the cell?

[@RBEMotion]

For this battery, I used 12awg wire to bridge the P groups, it's nice and flexible, so if they deck you're building on flexes a bit in a similar way, it would be a good idea to do something similar. For a 12s1p pack, you'd want to be careful where you solder, so as to keep as much heat out of the cells as possible. Mboards does sell single p group nickel, so that may be an option to consider. If you aren't doing a flex pack, you might be able to weld the whole thing.

[@VllKlNG]

Really nice video. Confused why the use of red and black wiring between the packs on the same terminals. Logically that would mean a short, but I'm guessing they are just jumper wires with the same potential... They could be any color of the same right?

[@RBEMotion]

Thank you! I just used two colors because it lets me burn through my stock of cables more evenly. If I only used red or only used black I'd have a bunch left over from the other color. They're all just series connections, as you can see, both red and black go to the same spots on each P group.

[@VllKlNG]

@@RBEMotion awesome - yea that seemed to be the only logical conclusion to me too, just couldn't see if there was something hidden by the camera angles. :)

[@RBEMotion]

@@VllKlNG Nope you got it :)

[@wesleyvinal9801]

This threw me for a loop too. Had same question…

[@RBEMotion]

@@wesleyvinal9801 Lol I apologize for the confusion, as I mentioned, was just efficiently using my available cables

[@urbandecay3436]

Is it cheaper to make your own battery pack or at least significantly cheaper to make the work worth it?

[@RBEMotion]

It really depends on how much stuff you already have, if you've worked with these kinds of things before, and if you're confident in your skills. Sometimes it can be worth more to someone to pay and have it professionally done by one of the many trusted battery builders. However, to answer your question, if you know where to get the stuff, and have the tools already, building it yourself is definitely cheaper. If you don't have any of the tools, and only need a single battery, buying one can be better for sure. Personally, I've built over 10 now and my tool cost has more than paid itself off.

[@SparkyJames]

It’s not cheaper at all if you only make one or two batteries. You do it because you want to make your own battery.

[@rylflush3427]

Nice video! is there a reason why one of the P groups at the end did not have a balance wire on it?

[@RBEMotion]

All of the P-groups do actually have a balance wire. You may be getting confused about the junction of cells 5 and 6. Since the end of the pack there is a common terminal, you only use one single balance lead to connect to it.

[@ДжабаевИбрагим]

Hi, nice video and its execution! Please, answer the questions. Have you used that battery and how did the soldering behave? Doesn't the vibration destroy it?

[@RBEMotion]

Thank you! This battery has seen hundreds of miles of use since it was built, and everything is still holding on strong. It was built in a way to withstand light flexing, even though the deck is quite stiff, and should handle the vibrations just fine since it was installed into the board using foam.

[@MadDonJuan]

Very nice tutorial. Thanks for sharing.

[@RBEMotion]

Thanks for watching!

[@mta3562]

Great video, where do you get your spot welder. Look like a heavy duty welder tips

[@RBEMotion]

Thanks! I got my spot welder from KWeld, techincally a German company, but I bought it from their contact in the US that sells them. The tips are pretty heavy duty. Sometimes they get dull but you can file them back into points.

[@prizmacore9439]

Whats a good place to buy 21700 li-ion battery cells from? I've been looking at the 18650 battery store.

[@RBEMotion]

Yep they're great, a lot of us buy from them. US based ofc.

[@jmtx.]

Awesome tutorial with everything very neat and tidy! For the tabs in Series, could they have been overlapped and spot-welded together instead?

[@RBEMotion]

Thank you! I would highly recommend against doing something like that. In my opinon, there is too much vibration and flexing in an esk8 pack to make something like that viable / reliable.

[@Eric_Tennant]

Nice build

[@RBEMotion]

Thank you!

[@medicforu6952]

what enclosure did you use for it

[@RBEMotion]

The enclosure for this battery is a custom kydex one that's on the client's board, I built it a long time ago.

[@Zachsnotboard]

thank you for this, I am going to have to repair two groups on my 18s 5p battery soon. I know how to solder from fpv drones but any advice for something 18s ?

[@RBEMotion]

Ah sorry for the late reply! Read this at work and forgot to get back to you. There isn't much different in 18s versus a 10s, just be aware of the situation and make sure you highlight your safety as your number one priority, the sparks from 18s are much bigger than 10s. If you're repairing a pack, I would check every single connection in the whole thing, since you're taking it apart anyway. What part of it seems to be broken? It's not good pratice to solder directly to cells since it dumps the heat into them so quickly.

[@dustenmaxwell8946]

Great tutorial! I'm working on a 12s4p 40t pack right now. Will be first time spot welding, though I've built 5 or 6 packs using outdated cell-level fusing with printed holders. Only question is why didn't you solder the charge leads onto pack before shrink wrap?

[@RBEMotion]

Thank you! I'm not exactly sure what you mean, the charge leads shold have been soldered on already, I just didn't connect it up to the port yet because that was still being decided on the customer's build.

[@dustenmaxwell8946]

@@RBEMotion oh maybe I just didn't notice them. I usually use 16awg wire soldered next to pack mains. Black to bms and red to charge port. Not doggin on ya 🤙 just watching heat shrink section and being like "where's da charge cords!?"

[@RBEMotion]

Ah gotcha. Yeah I usually do the same, 16awg soldered to main pos and then bms soldered / connected to main neg. It's also theoretically possible I waited to put them on since I later installed the pack into the client's board. In any case, this was a long time ago so I don't fully remember. All I can say is he's still riding it all the time!

[@SparkyJames]

That is a beautiful looking battery 👍

[@RBEMotion]

Thank you man!

[@awesomerpyt6594]

Great video ! Also wanted to ask if you would recommend using 21700 batteries to make a pack over 18650? What benefits or drawbacks there are one over the other?

[@RBEMotion]

Thanks! That's kind of an involved question and every build needs its own consideration to answer that properly. However, most 18650's are a thing of the past. The only ones worth using right now IMO are the Molicell P26a or the Molicell P28a. I would probably only use them in very space constrained builds, otherwise, 21700 is just the best option right now. Generally higher discharge and capacity.

[@awesomerpyt6594]

@@RBEMotion thank you for your answer.

[@Leenvanmaurik]

Nice vid! This is super helpfull! Thank you ❤

[@RBEMotion]

Thank you! I'm glad that you found it useful!

[@AlexRodriguez-nv9pr]

Where can I find the clear heat shrink you used? I would love to be able to see the inside of my pack

[@RBEMotion]

You can actually find it right on Amazon, just search for "Clear Battery Heat Shrinkable Tubing." the brand of the stuff I used for this pack was Causin.

[@AlexRodriguez-nv9pr]

@@RBEMotion would you be able to share a link to it. I can't find the specific one you're mentioning. Thanks

[@RBEMotion]

@@AlexRodriguez-nv9pr I would like to keep links out of my comments, if you shoot me an email at [e-mail] I'll send you the link!

[@quellcristfalconer9457]

For a 14s8p pack of the same cells, would 12 gauge wire still be sufficient to connect the p-packs? Or would 8 gauge wire be better?

[@RBEMotion]

For a pack of that size, you're looking at approximately 200-240A continuous according to those cells' tested rating. Personally if I were building it I'd plan for 250A. 12AWG many-strand copper wire is rated for approximately 41A continuous to stay cool, with 61A warming it up. 10AWG is rated to stay cool at around 55A, with 82A warming it up. For you, since you have way more current than the 12AWG, I would recommend at least 5x 12AWG per connection, but if I were personally building it, I would use 3x 10AWG wire per connection. To fully take advantage of the current of the cells, you want to make sure your wires are not a safety hazard or a bottleneck. Soldering all those 10AWG connections will be arduous, but it will be worth it in the end when you've got a pack capable of easily 250A continuous. Keep in mind that you will rarely pull that full potential unless you're on 4wd offroad, and you're heavy. For me, I would maybe consider 4x 12AWG and not set the current draw as high on my ESC's just because 4x 12 is easier to solder. Let me know if this answers your questions

[@MrJob91]

@@RBEMotion respect for the time investment into this answer. you're totally correct and it really shows your passion for battery building and the trade-offs you have to make between making something that works and spec sheets.

[@RBEMotion]

@@MrJob91 Of course man, high quality is always what I strive for.

[@SharvinSoosaipillai]

Hey video was awesome :) just curious about how you were able to recharge the battery when it dies. Is there are specific port on the BMS that allows for charging? Or did you charge it an alternate way?

[@RBEMotion]

Hey there, yes, the charge port connects to battery positive and the C- port on the bms. This allows you to charge it with whatever charge port you solder on.

[@SharvinSoosaipillai]

@@RBEMotion Thanks for the feedback, just a couple of follow up questions since this is my first time building a battery. For the BMS I have chosen, it is quite similar to the one shown in this video (as there is only a B- and a P-), so if I wanted to bypass the BMS, should I just connect it in the same way you have? Additionally in the BMS diagram, there is a P+ and p- area, but what does that area actually mean (does it mean the positive and negative terminals for the power)? Finally, once the battery pack is discharged, would it just go straight into my components (switch followed by my vesc in that order)?

[@RBEMotion]

@@SharvinSoosaipillai Usually, bypassed discharge will be very similar on all bms. It's always best to reference the official BMS documentation, not what I say though. There, you'll find what you need to know. P- and P+ can mean different things depending on the BMS and its design. When you're running bypassed discharge, your current will go straight into your load (vesc), which will need to utilize an internal voltage protection circuit (battery lower cutoff in settings) to ensure the battery is not over discharged.

[@SharvinSoosaipillai]

Sounds good! Thanks for the help =D

[@Brennen_Nisporic]

Great video. How much did the build cost ?

[@RBEMotion]

It cost my customer just under $500, however, battery build costs vary on complexity, size, and materials.

[@RhythmBlade]

What did you use to separate the nickel tabs abd keep them from touching? Also how big is this width wise?

[@RBEMotion]

What exact tabs are you talking about? There shouldn't really be any need to separate nickel tabs on this pack. All of the series connections are wired together anways. The electricity will take the path of least resistance no matter what. Width wise, it's 8 cells wide, so around 170 mm

[@RhythmBlade]

@@RBEMotion oh I see, my mistake I thought I saw something in the middle separating the 2 lol. Would you be able to provide a simple schematic for this at all? I'm just having a hard time recreating this from the video alone. Mainly just the way the positive and negative terminals are facing and the balance wires from the bms. I've made a 10s2p battery already but need to upgrade for the sake of my motors so i do have a bit of experience lol (enough not to blow anything up) and yes I'm new to this hobby

[@RBEMotion]

Totally get it haha it can be confusing at first. If you're building your own stuff I'd suggest making an account at forum.esk8.news to get more information than you even need lol I can draw something up or look for one, but it's fairly simple. There is an actual schematic represented in the video for the bms wiring but I get how confusing that can be, was hard for me too when I started a couple years ago. If I have time later today I'll try to find a layout. I'm actually filming another battery video today but it's a bit different than this one

[@RhythmBlade]

@@RBEMotion take your time! And the bms wiring is actually pretty easy to follow, I have an esk8 account but I just don't know how to post on esk8😂 but I'm in no rush so please take your time, you have a lot more important things to do! I'll study the video more and browse the esk8 forums in the mean time. Until then thank you very much for taking the time to reply and thank you for being so willing to help. I appreciat it very much!

[@RBEMotion]

Haha of course man always willing to help out. If you find more specific questions after looking around some more, feel free to ask again. Also, check out my other battery video, you might find it helpful as well.

[@bigmeme1429]

Hey Dude, nice tutorial :)) but I have one question... What is the total capacity of the battery?

[@RBEMotion]

Thank you, glad you enjoyed! The total capacity should be about 16AH, since each cell is 4AH, and there are four in parallel.

[@tkdluvsgoldens733]

why is lead 11 and 12 on the same pack? Will it read same voltage?

[@RBEMotion]

Lead 11 and 12 go to different spots on the battery, take a look at the diagram again 👍 Lead 11 would be between cell group 11 and 12, and lead 12 would be on the battery positive

[@odetteanoh1831]

For me you are ingeneer plus clever clubs innove plus great🎉.i like and i sucribe

[@RBEMotion]

Thanks for watching!

[@theslimzable]

Can this pack flex?

[@RBEMotion]

You've got a couple options. The simple answer as shown in the thumbnail is to not use heatshrink tubing. After placing the clear tubing around the whole pack, it is not able to flex. That's okay because it was going into a stiff deck. However, you can get around this by shrinking it and then cutting through along the joints, or using several smaller pieces across the whole thing. To directly answer your question, with the single piece of heatshrink, no. Without the heatshrink, yes.

[@theslimzable]

@@RBEMotion thank you so much!

[@RBEMotion]

Anytime!

[@odetteanoh1831]

Thank you for your help🎉 i like and i suscribe.great

[@RBEMotion]

Glad you enjoyed the video!

[@channel-ug9gt]

you could have just spotwelded the series together ... no wire was needed.... why not like that ?

[@RBEMotion]

That's a bit more of a loaded question than you might think. You are correct. You could just weld them together, however, that connection is nowhere near as durable as the silicon wires. Using silicon wires like this is our standard practice for packs in boards. Without the heatshrink applied to this whole pack, it could easily be completely flexible. Also, nickel has a very bad cyclic loading life, meaning that after repeated bends, it breaks. I would never want to risk a series connection breaking, so I use wires. There are certain applications where nickel series connections are appropriate, and you might watch my latest video to see that. I would typically only use nickel for series if I was absolutely sure it wasn't going to bend, or if the pack had additional supporting structures that take the load, rather than the tiny nickel spot welds. Does that make sense?

[@doncorley975]

Can someone give me a detailed battery build of a 10s5p flat or 10s6p I have 90 Samsung 32e

[@RBEMotion]

The build process would be extremely similar to the one pictured here, except that it would be wider. Usually we rarely do 5p in single stack and almost never 6p, because there aren't many enclosures out there wide enough to do that.

[@jamescalkins6069]

Would this set up work in an evolve GT, if I reuse the BMS from the original battery pack?

[@RBEMotion]

Hmmm - hard to say. I've never opened one up before. From what I hear they are pretty tight. Lee Wright did a video quite a while ago doing an Evolve GT mod, maybe you can figure out the answer to that if you check it out?

[@jamescalkins6069]

Would you be willing to do one if I sent it to you?

[@venomkill]

top my friend.

[@RBEMotion]

Thank you!

[@eBoard3R]

⚡🤙🏼🤙🏼⚡

[@RBEMotion]

⚡⚡⚡✌️✌️

[@terryyoung1473]

how can you solder a red wire and black wire to the same piece of nickle i am sorry i am a 60 year old rookie

[@RBEMotion]

This seems to have caused more confusion than I expected lol - I only used black and red because I wanted to evenly utilize the cable that I had laying around. The color doesn't really matter though, it could have been orange or purple or blue and it would serve the same purpose. All of those connections that go from the positive at one end, around to the negative at the other end, are the series connections for the battery. They are simply there to transmit the power through the pack.

[@Esk-be8kd]

Looks like my mboards battery

[@RBEMotion]

Haha yep, he learned from my videos and other advice!

[@top_banana]

You made a mistake. As I see the battery pack. You did 5 red wires on the top ones but missed the far left one bottom parallel set. Then doubled up on the far right bottom.

[@RBEMotion]

Well, it charges, discharges, and balances properly, and has been running for years - I don't believe any mistake was made. Sometimes, it can be confusing to look at some of the wiring. What you're probably seeing, is the fact that the 6th connection is on the bridged group on the left. What you see is one big contact, rather than two smaller ones. If you draw onto each of the parallel groups with a positive and negative, you'll see that I've hit the positive and negative on every single series group, without missing any. Each connection between cells gets one wire, and even though it looks like one is missed, its actually just connected on the opposite side of the same joined connection. Does that make any more sense?