fischertechnik 14500 rechargeable battery box

thingiverse

**Warning: Use at Your Own Risk!** Lithium-ion batteries are potentially hazardous if mishandled. Never leave them unattended or charge them without supervision. Not suitable for children due to the risk of electrical shock. Always use a protection cap to prevent short circuits. I needed a compact, rechargeable battery box that would fit in my Fischertechnik setup and provide more power than standard 9V rechargeable block batteries. Since the 18650 type is too large, I chose two 14500 batteries, which allowed me to design a small 30x20x60 mm form factor. Together, they deliver around 6.0-8.4 V, sufficient for many Fischertechnik applications. To use with unprotected batteries, I included a [HX-2S-01 protection shield](https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=2S+5A+Li-ion+Lithium+Battery+Protection+Board+Pad+Module&_sacat=0) in the design to prevent overcharging and -discharging. You'll also need a piece of 0.8mm wire for the contacts and some pin headers. When using this box for the first time or after changing batteries, you must initialize the protection board by applying a charging current to the P+/P- contacts (or the + / - contacts of the printed case). If the batteries are charged, you can simply use their own current to do so, which is convenient if you charge them externally. Check the images for instructions on how to connect from the board's P- to B-. If anything is unclear from the pictures, please send me a message and I'll provide further information. Please consider showing your appreciation by leaving a "like" or posting your make. You can find my other Fischertechnik designs [here](https://www.thingiverse.com/juh/designs). Watch a video tutorial on how to assemble this box: https://youtu.be/hU7KIjeh6Fw