Identifying that BAD 18650!

Just under this melted white insulation is the negative contact. With time and vibration you could have a :fire: I bet many of the cells look like that under the copper bus bar from the heat of soldering. All the positive ends should have the fish paper circle insulations. I would at a minimum rebuild all the positive sides if you want the pack to be safe after solving the bad cell issue. Sorry to spam your thread. image


This will just get them hot again. Less heat is better. IF that was to be done, only on the poisitive ends for sure

All that’s separating these cells, insulating them from one P pack to the other on top of it, is about 0.2mm of heat shrink! No + ring protectors either! :hushed:

Honestly I’d either bin these cells and get a properly built pack or if you really have to, de-solder everything, disassemble them all and start over with proper insulation and silicon coated wire…


I bet there’s friction scuffs already on the heatshrinks. 0.1 now. The balance wires look like they’re rubbing and the BMS isn’t even wrapped up. Parralel connections more built up than series?

If you have to take it apart use a Dremel or some wrenches to pull the copper out. The less soldering the better. When you build batteries you need to imagine if anything close or overlapping were to make a connection. Which usually ends in catastrophic failure unless it’s a p group. For a 12s10p you need a lot of fishpaper

That’s a bomb! Or at least the picture which @rojitor posted.

Get rid of this battery, I know it’s a lot of money but how much is your life or your family worth?

The hot glue has no contact, no isolation at all, mechanical stress on all solder joints only, no padding (on a MTB bro, that must shake well). How long did you use this battery?

I know there are not much fans of soldering Li-ion but it’s possible. Soldered this pack with 80-100W iron, flux, flat copper wires (3mm²) and copper bar for serial connections (4mm²), works flawlessly.

112038h 221416h 220157e

Furthermore I put fishpaper on all battery poles after soldering and heat shrinked all paralell packs. Between the packs is 2mm neoprene rubber and also around. Everything inside enclosure is glued with flexible glue.

After my heavy crash where I destroyed the front truck and cracked the deck only 2-3 packs shifted a bit but everything is working also thanks to flexible wires and padding. If I had your battery it would look different.

Please rethink your battery design, it is very dangerous.


all- thanks for all the responses - a note on the board , this is my first eskate and I purchased it used about 3 weeks ago for 800 quid , I come from a quadcopter background so know what I’m doing when it comes to the electronics - never used a BMS on a quad so had to read up how it worked and did kind of think that the way this was wired looked dangerous! I have gone on it at least 10-15miles /charged it twice only as kept cutting at 44v, i had not opened the case as it was cable tied shut (i thought cabled tied to the board) so had not seen the state of the battery.

However I have taken your comments on-board (no pun) everyone’s shock and horror at the pictures and rojitor’s picture made me pull the trigger and I ordered 4x16000mAh 6s Lipos, will run them as 12s2p (2 for spare to take with me on long rides - the battery box can take all 4 with room to spare) , would I need a BMS with 2x lipo or could i just wire them in? If so could i use the one i already have? Either way I would remove the batteries and use a balance charger to recharge them everytime. And I agree it looks like a real mess ! Thanks for all your replies. Took me so long to reply as i had reached my post limit and had to wait 24hours!

I removed all the 18650’s and thought you would enjoy the pictures, any one want to buy 120x18650 buy assumes all responsibility :smiley: lol :smiley:

IMG_2521 IMG_2520

And the board: A3D8D2F7-3AEA-46C1-90CE-592B396CF946%20(1)


lol dude, how many different cells are those :smile:

no self-praising here, but thats a good soldering


I was wondering where you went. Haha.

That battery may get the award for the worst one on this forum. :nauseated_face: :face_vomiting: :fire: There is nothing about the construction that could be considered even sub standard.

That BMS is ultra weird too and the size of bus. It must be recycled from something large.

If you have a hobby charger you can just ballance on every charge cycle and not use a BMS. Just one tip though, hotglue all the ballance connectors wires just near the plug, both battery side and charger side. I found with constant use one pin can come loose and you could charge the pack minus one cell and not notice.

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OMG there are more of them LOL

I’m getting anxious just looking at the pics, get those somewhere fireproof ! :slight_smile:

Well everyone - Thank you all for your help, thought you may enjoy an image of the battery bay now :slight_smile: