Cylindrical cells - How do you do your final terminations?

[jonescg]

I recently re-packed an e-bike battery for a friend using 18650 cells, and while the hexagonal Kart kit was a dream to work with, the final terminations had me scratching my head. I ended up spot-welding the last parallel cells with excess tab and soldered heavier gauge wire to it - maybe 2.5 mm2 and adding connectors to that. I should also add I built a little case with FR4 and tape and potted the whole lot in epoxy resin.

But the end termination was pretty inelegant. Does anyone else have a nice solution for robust, high current connections to the first and last cells of an 18650 pack? The trick is to reliably get the power out, share the current evenly, and ensure it's robust enough to survive a thrashing.

And yes, I forgot to take a photo of the whole lot :x

 

[999zip999]

How big of a battery are you building and what are you going to be using it for how many amps

 

[jonescg]

In my recent case, it was 6p7s for a 24 V system. So there were three cell ends I spotwelded to and then soldered onto these bits of nickel tab. But it could have been 20 wide - the issue is the same. How to safely, and neatly get the power out.

 

[999zip999]

I was asking for the reason are you going to pull 20 amps or 80 amps that's the difference in the bus bar.

 

[jonescg]

Assume 1C continuous, or about 3 amps per paralleled cell.

 

[goatman]

ive been playing with the magnets and i was thinking of doing a bus bar sandwich.

1 magnet battery end, no magnet on the other where it gets sandwiched between copper bus bars and flush riveted. i dont know if you can spot weld copper in between 2 nickel strips with the magnet tabs. i might need to draw a better picture