Battery pack thread - SHARE YOUR TIPS, TRICKS, FAILS ETC

I’ve seen a few where the entire pack is wrapped thick with kapton tape instead of using heat shrink, that gives me concerns about heat. But also I think the ‘heat proof’ part is more about withstanding heat than preventing it from going through the tape

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Good point. I’ve learnt that lesson. Now I stick a bit of fish paper on any cell blocks next to what I’m working on. And I like to do the parallel side first, too sketchy when the series is done and you’ve got cells that close

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I think we should be happy that it wasn’t the 2 main leads. 10:36 he was also really lucky.

When you fold the battery do you just fold it or is there a secret trick?

I totally forgot about that, thanks!

there’s a bit of trick. problems can occur if the fold is off-center because one cell blocks will be higher than the other. once the nickel has a kink its fairly impossible to move it. so as you fold them open, leave them apart a little then push them firmly down against the table as you push them together

after watching Homeland i often feel like im building a bomb haha :flushed: particularly with the balance leads :rofl:


@TinnieSinker remember the battery pack could get off-center? Well it happend. And you were 100% right. It’s impossible to fix. It doesn’t really matter to me since the battery fits without any problems.

IMG_3518 IMG_3523 IMG_3520 .


oh bummer! though at least it still fits. bit of foam will fix that gap, no worries

how did you do the nickel in the middle? curious as i’m about to do a double stack pack as well

For the spot welder part I had a total of 6 nickel strips crossing. 2 layers X 3 cells.

It was quite hard to bend it when it was flat with the table so instead I lifted it and then folded. Should probably had kept it on the table and lift it up slowly while it was bending.

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Save the center portion of your fish paper gaskets. They work great as a cell spacers for your P packs. 20181104_130415 20181103_224546 20181103_224553 20181103_224544 20181103_224549


I did my best with this external range extending battery to isolate all the P groups with multiple layers of masking/fiberglass/electrical tape. I re-used adhesive backed fish paper for some of the wires, and kept fish paper on all the positive leads. I sandwiched every wire with electrical tape. The pack works great, it’s probably not up to the standards of everyone else here… But you guys think it’s still safe?

I used a bestech BMS with discharge bypassed, charge only. Charges great, discharges great, and I’ve got a low voltage alarm (that reads a little low, 0.3v low on average, I guess this is good) to monitor each of the P groups, and since I won’t be using it if I’m not riding or next to it, I’ll know when to pull the plug if a P group gets too low. All in all, the pack tests out to about 400wh, 6S6P.

To seal it all up I did a wrap of electrical tape on all exposed parts, glued craft foam to make it as evenly shaped as possible and remove stress from around the BMS, charge, and discharge wires, and taped it all up tight with more fiber tape.

Pics of the build:

20181104_215520 20181104_215531 20181104_220524 20181104_224712 20181104_230759 20181104_233924 20181104_233947 20181105_002838 20181105_010305 20181105_011555 20181105_011902 20181105_013154 20181105_024706 20181105_024822 20181105_024942

I’ll be working on printing an enclosure for it that snaps securely to the board and hopefully looks badass too.


I’ve had my board running for one day and already know I want a range extender lol


I’ve found that half of the cure for this (besides increasing battery ampere*hours) is learning how to ride in a way that maximizes range. Just something I learned makes a huge difference that I didn’t suspect as much


I think changing the gearing up will make a huge difference , cuz currently I’m pretty much going max speed all the time.

I think that’s better for range :man_shrugging:

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Wow just wow. Is it a scooter arm?

Curious as to how you performed this test. Did you just take a lighter to it until it caught fire?

Have you ever looked at a spec sheet for fish paper? Did you know that there are a lot of different types of fish paper and that most of them are not fire retardant? They are not meant to be fire retardant. Fish paper is used as a tough, wear resistant, non-conductive, protector for electrical applications. Most of them are rated up to 150C. Do you know the temperature of an open flame from a lighter? Some fish paper types are waterproof but most aren’t. Very few are fire retardant but vast majority are not.

All of this to say, that you have unrealistic expectations from fish paper. The reason it is used in battery making is to provide a excellent dielectric and wear resistance while being free of any conductive particles.


Kapton tape will work fine, it is electrically non-conductive but has good thermal properties, it can be used in wider temperature conditions than most other tapes and it is also a good thermal conductor (as far as tapes go)

The only issue is that kapton tape is not wear resistant and is easy to puncture. So if that’s of any concern I would not use it there. Fishpaper would be more appropriate.

I suggest you look up spec sheets for all these things. You will learn a lot.

When working on cells right next to another bank and there is a possibility of shorting, I use fridge magnet kind of mats on top of the exposed parts that I’m not working on. These stick to the cells and won’t slide around, are electrically non conductive and you can move them and reuse them as many times you want.

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Thanks! It’s a longboard:

maybe its time for current control? :thinking: