Automatic AA battery charger

Fully automatic (robotic) AA battery charger made with 3D printer and micro:bit. You just need to "pour" batteries and it automatically charges them one by one. The charging time of each battery is recorded separately and shown on the display. You can add Bluetooth monitoring / controlling features.

Necessary parts

* micro:bit (approx. 20 USD) https://microbit.org
* SG90 compatible mini servo (approx. 3 USD)
* any battery charger with charge status LED
* (optional) sensor shield (breakout board) for micro:bit (easy to connect the servo to micro:bit). For example, Keyestudio Ks0360 (approx. 10 USD)
* short parts
- spring extracted from cheap ball-point pen
- battery contact material (thin metal sheet)
- electronic wires and solder