Spring-loaded 18650 battery jig with banana jacks

An experiment in printing banana jacks and dovetails. Allows for flexible wiring. E.g., charge loose Li-ion cells in parallel, discharge in series.


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Printed without support at 0.65mm extrusion width and 0.4mm layer
height. Sliders were printed w/ 2 perimeters, the box with 1. You can
dial your favorite number of slots in the openscad source.

The banana jacks are experimental. My specimens are still going stong
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

I use 5cm pieces of 3mm dia. PLA filament as spring guide (ballpoint
pen springs will buckle when not supported). I straighten the pieces
by heating them with hot air until gravity starts to bend them, then
let them cool while rolling between two flat surfaces.

When friction-welding the spring-guide to the slider, I put the slider
on the rail and spin through the hole in the box to get the angle
perfectly. I move the slider slightly during welding to ensure that
the filament does not weld to the box.

Materials and methods

- [ per slot ]
- 2x 6cm length of 0.6mm dia. nickel/silver/gold plated copper wire.
- 1x compression spring from discarded ballpoint pen.
- 1x 5cm straightened 3mm dia. filament. (used as spring guide,
friction-welded or glued into a pit in the slider)



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4c4effa45c4dec417fc96ff7a11d0f8c?default=blank&size=40pul added this to the pp collection ago
05c026b73c89410a114b66062add7971?default=blank&size=40Tamion added this to the Elektronik collection ago
9ff4fb83040fbc1cafe1637ce1e0e166?default=blank&size=40jonasbits added this to the 18650 collection ago
4b1c6773c6915c60390afd75a5e222d0?default=blank&size=40HAMMER_T added this to the Electronics collection ago
396e53047db5fedbd8c27c2ef7509f97?default=blank&size=40drofnas added this to the Parts collection ago
C547b810270b9980d0200c7f15c58e0a?default=blank&size=40ThomasBe added this to the tools collection ago
Mini youmagineavataransel published this design ago