Battery clasp for three 18650 cells.

youmagine

Printed on my RepRap Prusa i2 without support at 0.65mm extrusion width and 0.4mm layer height, single-perimeter, 20% infill. I use the clasp to charge loose li-ion cells in parallel. One could also wire the clasp for series connection of the cells, but I recommend against that, as one needs to be much more careful when assembling a pack, and accidentally short circuiting li-ion cells is something to avoid at all costs. The banana jacks are experimental. My specimens are still going strong after about 50 insertions using 0.6mm wire. The jacks appear to work best with plugs that have a "cage spring". Classic plugs with a "banana spring" work too, but you need to orient them so that the spring opposes the wire for reliable contact. The "bunch of springy wire" style plugs don't seem to work reliably because the contact wire sets itself between the spring wires instead of compressing any of them. As an alternative to banana jacks, the 4mm holes could be used as strain relief for stranded wire soldered to the contact wire.