Looking for feedback on the battery I built

Hey, so I was a little overly anxious to get started on my build and after putting several miles on it now I’ce decided to come back and see what I can do to refine my build. I firstly wanted to get the communities thoughts on the battery I made. I’d also like feedback on the ideas I had for mounting the BMS and FOCBOX to the bottom of the board.

First off the Battery. I didn’t have a large enough shrink warp so I took two pieces and taped it together. It worked surprisingly well :smile: the second smaller wire goes to my battery meter which has an on off button so I can check the voltage without connecting the loop key. I tried to use fish paper to isolate the 2 rows of cells but realized after the fact that I have nothing between the cells in the other direction… I’ve seen at least one person mention that the hot glue I used might not be sufficient at holding everything together since it can melt if the battery warms up enough I’m hoping that the balance wires will be ok in the configuration but want others opinion before all my hard work goes up in flames: Overview%20of%20battery Bottom%20view%20of%20battery Negative%20lead Possative%20lead Left%20side%20of%20battery Right%20side%20of%20battery

Here is the FOCBOX mount I designed and printed. I drew a lot of inspiration from what is available on buildkitboard.com as they offer a 3D printed mount for sale. I added space next to the FOCBOX so can use double sided tape to mount the receiver as well. I will use the rest of the empty space to mount the Bluetooth module I ordered to the plate as well most likely using more double sided tape. FOCBOX%20mounted%20to%20plate FOCBOX%20and%20plate

Lastly I wanted to connect the BMS to the bottom of the board as well so I made a very simple mount specifically for the Bestech BMS. I had to swap the screws from the top of the BMS to the bottom since they were longer but I think it will work out nicely (P.S. this bms id dead because I accidentally put power through the e-switch wires :frowning:) Top%20of%20BMS Bottom%20of%20BMS

Thanks in advance for all your input. This community has been awesome to be part of!



Things like this are generally considered dangerous. If something pokes that corner and pushes either one under the insulation it has the potential to short out the P group.


I tried to keep an eye on that sort of thing on the possessive side of the battery, would you say its a better idea to have trimmed the corners so there is less of a chance of something like that happening?

Yes I believe the current consensus on the forums is that trimmed corners are preferable. I think that was how @deltazeta 's board went up in smoke?


One thing is that the balance wires shouldn’t cross over each other. Reduces the chance of them shorting each other out


Ok, I can remove the heat shrink and clean that up but what would be the advised way of doing so? should I just run it through channels between battery and then back up to the end via the gap between the two rows of cells?

IMG_7676 Clean balance wires are key!


looks great :open_mouth:

oh damn… looks like I’ve got some work to do tonight :slight_smile: lol fantastic battery!

What size pack is this? Do you mind sharing what it cost? I’m curious on the pricing of lipo vs li ion.

Great first build man. One thing that is guaranteed is help with batteries on the forum. I’ve probably done more research on battery building than any other aspect and still haven’t had the nerve to build from scratch.:sweat: Have rewired a new bms though and used the gurus on here to do it right. Still managed to cross over 2 p packs in my connector. Bms started to heat up on its own and man theres nothing like that to make you change your undies. It was easy to spot though because of the tidy routing and labelled packs. I now do all my battery tinkering even just connectors etc outside on my deck with a fire extinguisher nearby. Point is check and double check and then check again. Mistakes are easy and there are no second chances with batteries.

This is a 10S3P using Samsung 30Q I bought from Nkon. I just put together this parts list and it turns out the battery cost more than I though it did lol… but on the plus side I’m going to make back some of my money by helping a friend build their battery and he’ll buy some of the parts from me. Looks like I was just under 300 but now I’ve got a spot welder and the knoledge and confidence to make another battery for friends :slight_smile: (on a side note I went for a 4.3 mile ride the other day on my board and only used about 27% of the battery capacity!! image

EDIT: I should mention that some of that I had to use for others parts of the build like the silicon wire and the xt90 plugs so they weren’t 100% a battery expense

yeah, I accidently put power through the e-switch wires on my first BMS and fried it… felt like such an idiot… when I got the new one I sat down double/triple checked everything and then like an idiot totally over looked that the first balance lead was connected to the wrong spot… I was lucky that it only fried the e-switch and I am still able to use the BMS with a loop key. The fact that I’m helping a friend has made me reach out to see what I can do better for the next time and how I can improve on my first build. I just came back from pulling all the balance leads off the battery and trimming them but I’m still not happy with it… I made the leads too short and the BMS is almost touching the battery on the one side… I’d like another half inch of slack to allow some movement due to vibration and what-not. Either way this is what I ended up with after the first go at “improvements” I’ll do it all again tomorrow and that time I think I’ll take a different approach and see how it works out.

Thanks everyone for the advice and suggestions so far!!


I trimmed a bunch of the excess wire from the leads but like I said I took too much off on some… I keep trying to use the fishpaper between the rows of cells but I feel like its a big part of why I’m having a hard time… I suspect is still probably advised that I use it unless someone has another idea. I think I’m just stuck in a rut and can only see the one solution… I like the example @ARetardedPillow shared but not entirely sure how I can replicate that. Its going to be my goal to morrow though.


Yes, except I wouldn’t cross the balance wires over one another until after they exit the cell area, then cross them all over so they’re in the correct order

Right where those cross each other will wear down due to vibration eventually making a place where a short could happen

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And just to be safe I try to connect the balance wires to the negative terminals as opposed to the positive ones, because in general the positive side of the cell is more dangerous

Honestly that was my goal but, I failed miserably lol. Like I said I’ll do better tomorrow :slight_smile: I’ll definitely make sure to avoid crossing any wires till i’m out of the battery

These aren’t balance wires, but they were accidentally crossed for about 200 miles and they had already worn through the blue heat shrink that was against them and there was a big indent in the insulation right where they crossed. Just because they were crossed. It creates a pressure point. Had I not caught this, it would have caused a failure (best case) or a fire (worst case)


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did not know that. and like I said hours of research. I probably saw it a hundred times and it didn’t sink in lol

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This is the best ballance wire job I have seen. There still is some crossing, but can that be totally eliminated? I guess the crossing can be after the cells in the free air just before the balance plug. They are well insulated from the cells though. IMG-20180704-WA0018

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That’s really good-looking. Who made that?

I would bring the wires out of the battery in the same order they happen to be in and not cross any, then cross them all in the circled area