# 18650 cell Kit development



## electro wrks (Mar 5, 2012)

Fantastic work. Do you think you can get away with not having some kind of spring loaded electrical contact points? It could be only on one end of the cells, with the cells floating somewhat in their mounts. Normal cell length tolerances, age, and corrosion factors could cause problems with your design. I was looking into cold worked (maybe heat-treated) brasses and beryllium coppers as the spring contact/conductor material. The beryllium copper apparently has some toxicity issues. 

Maybe I missed it. What C-rate of discharge were you using for the heat build-up test? At one time I remember checking into specialized heat conducting, electrically insulating plastics for the shell material of batteries like this to reduce heat build-up. 

Great work, don't forget to feed the baby.


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## riba2233 (Apr 29, 2015)

That space in the middle could probably fit a BMS, so you would only have two wires coming out


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## agniusm (Apr 30, 2012)

I don't think there will be unloaded contacts as measurements taken at the weakest point on the edge if you can see how standoff pattern goes. Cells are not floating. On one end there is rigid backing of the cover, on the other end low set polyurethane foam from Rogers. Its 1.6mm thick, compressed 50% so it will allow for cell contracting and expanding but will keep it firm in place when external forces are applied. Its 1.8kg per cell compression, its not that bad. Spotwelding is done at .5kg pressure or less. Regarding corrosion, my solution is nickel plating. I've done it on my second prototype, but thought I don't need to waste money on prototype cause it won't see corrosion being warm and dry Here is the proto 2:










Riba, yes, I bet you could squeeze BMS no problem. Bestechpower has compatible ones by the size.

I have new design comming for sale in 6,5,4,3s flavours with discharge limited only by cell type. Stay tuned, same tech inside


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