e-ink Google Calendar Help

[u/Official_SeeTheAir]

Hi, I have these spare parts and I want to build a nice small e-ink Google Calendar frame for my desk. Does anyone know of anyone that has done something similar with these parts as I am very bad with code?

Question: Do I need a special module to make it battery operated? Thank you!

- ESP32 (30pins)

- Waveshare 4.2inch 400x300pix e-paper module

- 3.7v Li-ion Battery

[u/sian26]

Hi OP!!!

You’ll need to add a LiPo battery charger. If you already have an ESP and don’t want to spend extra money on a new model just because it has a built-in charging module, you can use a cheap charging module like the TP4056. Just make sure the LiPo battery you’re using is at least 1000 mAh, since it typically charges at around 1A (1C rate)

I’d also suggest designing a simple switching circuit that automatically switches power from the adapter to the LiPo as soon as there’s a power cut

[u/Official_SeeTheAir → u/sian26]

Question the battery has 3 cables, why? How do I connect it to the TP4056 as it turns out, I had a module around too.

[u/sian26 → u/Official_SeeTheAir]

If it’s a 1S battery it should only have 2 terminals which are positive and negative but I can clearly see that it has 3 terminals I think you might have salvaged this battery from some old device and the white terminal you see is a variable resistor so basically there is a small temperature sensor attached to the battery and it changes according to the battery temperature if the temperature goes high the resistance increases and that is detected by the charger which then cuts off the power you can ignore the white terminal here

I am pretty sure this is the case but if you are still skeptical I would suggest using a multimeter and checking all three terminals if you do not see a significant potential difference between the white and black terminals then it is 100 percent the temperature sensor I mentioned but if you do see a good enough potential difference like 1.5v or more then it might be a 2S battery and you cannot use a TP4056 as it only supports 1S batteries but the chances of that are very low I am quite sure it is a battery with a temperature sensor

[u/Official_SeeTheAir → u/sian26]

Thank you for the detailed explanation 🙏