ESP8266 Community Forum

- Sun Aug 14, 2016 4:15 pm #52952 Hmm, LiFePO4 batteries look like a good option. However I can't find them in any online store in the backwater country I live in. (I found one being sold for like $20, screw that).

I guess I'll stick to 3xNiMh batteries then. Or if I'm going to stick a regulator in there, I may as well go for 1xNiMh with a step-up regulator.

I read about people using a diode in conjunction with a 3.7V LiPo to drop the voltage by 0.7V, maybe that's worth a shot?

- Mon Aug 15, 2016 4:23 am #52974

I read about people using a diode in conjunction with a 3.7V LiPo to drop the voltage by 0.7V, maybe that's worth a shot?

Hi, yes this works, but during low power states (deep sleep) the current can drop below the diodes minimal working range and the voltage creeps up to the 3.7V. This need not be a problem as it 'seems' that the ESP can withstand 3.7V if not being run to hard - just watch for charging or fully charged voltages that are higher. If you can a voltage regulator is a better all round option as you'll get a better useable voltage range from the battery.

- Mon Aug 15, 2016 1:40 pm #53005

I read about people using a diode in conjunction with a 3.7V LiPo to drop the voltage by 0.7V, maybe that's worth a shot?

Hi, yes this works, but during low power states (deep sleep) the current can drop below the diodes minimal working range and the voltage creeps up to the 3.7V. This need not be a problem as it 'seems' that the ESP can withstand 3.7V if not being run to hard - just watch for charging or fully charged voltages that are higher. If you can a voltage regulator is a better all round option as you'll get a better useable voltage range from the battery.

Ah yes, I read about that, but since this project won't use deep sleep, but will power down (thanks for the idea from your post by the way!) instead, that shouldn't be a problem.

If I did use deep sleep it would be a potentially serious problem as "3.7V" batteries actually go up to 4.3V when fully charged, which will definitely fry a 8266 from what I've read.

I think it'll probably be simplest to use 3xNiMh batteries. But I also have one of those power bank thingies (which seems to house a 18650) which I could potentially use in conjunction with a butchered USB cable and a 5v to 3.3v regulator. But finding one with enough max current, low quiescent current, and high efficiency would probably be difficult. (I'd probably have to order one from aliexpress and wait 2 months for it to arrive).