2x 18650 holder for headlamp strap

I have a very nice headlamp, but it's way too power hungry for a single 18650 cell, even after i swapped it for one with more capacity. The charging circuit is way too weak, so it takes ages to recharge I created a simple plate that fits onto a 20mm wide strap, then merged it with a modified 2x18650 holder The original model uses wires for contacts. I made the holes wider to fit a 5mm wide nickel strip, which makes a far better contact, as well as being easier to assemble. The holder model is also simplified to get rid of markings and wire channels. There is a small gap between the plate and the spring part, created by a negative volume setting. It should be filled with easy to remove support material to make the spring move freely. Use supports -> everywhere to do that Holders themselves are very slightly enlarged to make it possible to insert/take out cells without tools. Original model's size makes it impossible to get them out without prying with something flat

Printing - PETG is probably best for this. Use whatever settings you want in terms of layer height and infill, but make sure that the thin parts at the ends are printed solid for durability (maybe use 4-5 perimeters for that) Assembly - make contacts using wires or 5mm nickel strips, connect via soldering or spot welding. Connect holders in parallel, and attach them to your headlamp's battery contacts with a flexible wire. I also used a strip of double sided tape to add a piece of foam packaging material, so that the flat plastic piece doesn't press against my head ! Make sure that cells used in parallel are equally charged to avoid high charge distribution currents ! Also consider adding some kind of reverse polarity protection if your headlamp doesn't have it already (a high current shottky diode, for example)

Category: Tools