De-soldering cells from an e-bike battery

[Linnarl]

Hello!

I have aquired an ebike battery (36V 15Ah, very good condition) pretty cheap, and now I'm thinking about ways to utilize it. One idea is to upgrade my existing electric longboard, however this would require de-soldering the cells of the pack and mounting them in a flatter fashion to fit the board. This leads me to my question:

What ways are there to de-solder the spot-welded cells of the e-bike battery for reuse? They are mounted in groups, each cell welded to a plate grouping them in parallel with 6 spot welds/cell (roughly)

Ideas? I can grab some pictures if needed.

Thanks!

 

[amberwolf]

if they're spot welded, you can't desolder them, as they aren't soldered.

You would need to cut the connecting strips, between cells, only at the points that make cell groups the size of what you need them to be.

Do not remove any strips from any cells; don't break any spotwelds.

Whereever possible, keep all the parallel cells in one group together, if they'll fit in the space you have.

Wherever possible, keep the series connections intact, too, and just "fold" them so the cells are end to end instead of side by side.

Reconnecting the cells together could be done either by spotwelding if you have a spotwelder, or by soldering sufficiently thick wire on the very ends or edges of the strips, as far away from the cells themselves as possible, to avoid heat damage to teh cells.

Use the largest tip possible, often called a hammer or chisel tip, usually close to the size of an average thumb. That holds enough heat to very quickly heat the area and the solder and make the joint, so you can remove the heat before it reaches the cells.

Other pack building and repair threads around the forum have more detailed info, but it may be a lot of reading to find them.

Toolpack re-use threads probably have the most info on cell rearranging.

 

[Linnarl]

Great information!
I can likely fold out all the parallel groups, resulting in a pack as long as 10 cells end to end. This won't fit my usecase, so I'll try to snip the pack in two and connect by a thick wire between them. I'll look into the threads you suggested as well, thank you!