I would build a small present for my friend's child who has a 3D pen like this:
3D pen link
By now it only works with an AC-DC adaptor, so it always requires a wall plug. My idea is to build a battery pack to allow the use even when there's no AC plug.
Reading the "3D pen tech. details" I sketched some project requirements:
- voltage: 12V
- current: 2A (max I suppose)
- Li-Ion battery like 18650
- At least 3000mAh capacity
- Integrated IC for battery recharge and battery over-discharge protection
- Others IC to protect output and avoid overheating etc (if required)
- 3D printed custom case, so I'm not too dimension limited (smaller is better obviously).
My first idea was to use 4 18650 cells, to reach a voltage between 16.8V (full charged) and 13.6V. Then using a step-down board to level voltage to 12V.
Another solution will be using only 3 cells (12.6V – 10.2V) without any regulator, and using only a over-discharge IC. This solution is the simpler, but I have no idea if the pen would tolerate under/over voltage.
What do you suggest? There's any other solution to achieve that?
Best Answer
Buy a mini-UPS from eBay. They are cheap and some of them provide a 12VDC output as well as a 5VDC USB socket for emergency phone charging. They have internal Li-ion batteries.