Spring-less Dual 18650 Holder (w/ Charging Module)

thingiverse

I'm working on a project that involves powering some Wemos D1 minis using 18650 batteries for extended periods of time. I purchased battery holders from Amazon, but they were subpar - cheaply made and had such a tight fit that the spring wouldn't push the battery up to the positive connection. I decided to design my own battery holders instead. The design is straightforward: there's a top cap with a slot for a charging/protection module and a bottom cap for the batteries alone. You use simple tabbing wire, often used in custom solar panels, for the leads. For each end, 52mm of 5mm tabbing wire will be used. Fold over the wire at 12mm from each end and insert it through the cap, then fold it around the detents. Place rubber bands in the notches on the holder top and bottom to secure the tabs onto the battery leads. The charging/protection module is relatively common, and I've linked to the ones I'm using below. The module should fit snugly into the slot. I used hot glue both as an insulator for the board leads and to hold the board in place. There's a long slot running along the bottom of the case for the lead wires and a slot at the top to charge without removing or dismounting the batteries. The design consists of two outer shells, one with mounting holes and the other plain. In my tests, I was able to power a Wemos D1 mini powering 26 NeoPixels for about six hours before they started showing any signs of power degradation - and even then it was some very light flicker at the end of the string. At around eight hours, I stopped the test with no further degradation observed. Disclaimer: When working with lithium-ion batteries, you need to be extremely careful. These batteries can explode, so if you don't know what you're doing, it's best to pass on this project. What I used - apart from the printed parts and basic hookup wire: Charging module: https://www.amazon.com/gp/product/B071RG4YWM/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1 Tabbing wire: https://www.amazon.com/Nickel-0-1x5mm-Battery-Welding-0-15mm/dp/B07W6VFFYS/ref=sr_1_2?keywords=5mm+18650+tab&qid=1584331035&sr=8-2 (I actually used .2mm x 5mm but that seems to be no longer available) 18650 Batteries: Since I'm using my own protection circuit, I'm happy with non-protected batteries. There are many fakes and questionable batteries on Amazon, so maybe stop by your local 'vape' shop and ask them for a decent battery. Keep in mind that the module above is a charging module and only delivers battery voltage (~3.7-4.2) out. This is fine for the Wemos and NeoPixels but if you need a constant 5v or something, you'll need a different module.