ESP8266 Community Forum

- Mon Apr 15, 2019 3:04 pm #81817 hi, I have an akku which delivers 3,7 V. I want to use it with a WEMOS D1 mini pro (V1.0.0) which normally accepts 3,3V. Is this a problem and do I have to size it down?

- Tue Apr 16, 2019 6:38 am #81828 For V1 of the Wemos you can use the battery power supply shield.

This shield is also able to charge your battery.

Assumption is the mother of all f*ckups. At least: that's what I'm assuming.

- Thu Apr 18, 2019 7:15 am #81867 From memory, I believe the maximum Vcc voltage of the ESP8266 is 3.6V.
Your battery has a nominal voltage of 3.7V, but it varies from 3.0V to 4.2V depending on whether it is empty or fully charged. So the 4.2V will probably kill your ESP is you connect it directly.

A method I have used before is boosting the battery voltage to around 5V using a step up converter module.
https://www.ebay.com/itm/DC-3-24V-to-5V-28V-9V-12V-24V-2A-Adjustable-Boost-Step-Up-Converter-Power-Module/112619032791?hash=item1a389e10d7:g:NE8AAOSwvDpbBoGe
And then a 3.3v linear regulator to make a nice and steady 3.3v (for example LD1117v33) with plenty of power. Maybe not the most efficient way, but it works fine.

- Thu Apr 18, 2019 2:08 pm #81887 thank you both answering that quick! I didn't thought about the voltage range. But this sounds like an idea. What do you think about using a LM 317 instead? But maybe if the Input changes the Output may vary too