ESP8266 Community Forum

- Thu Jun 30, 2016 3:40 am #49985 Hi guys,

This is my first project with the ESP8266, so i went with the NodeMCU development board for ease of use. So the i have just about completed my weather station that has a DHT11 and a BMP180 attached to it. Now the issue i have is what is the best way to power it. Currently i have it connected to a 1800mah power bar. Unfortunatly this seems to only last 2 - 3 days before it needs a charge. I also have the board going into deep sleep after every reading( every 15 mins).

Obviously this is too short of time and dont want to be changing the battery every 2 days. I have got some 5V solar cells, but unfortunately the power bar is unable to charge as it powers.

So what i am looking for is a solution that allows me to change the battery every 2 weeks or to be able to have the batteries charge while being used.

I am still new to this so please go easy on me.

Many thanks in advance,

Jonathan

- Thu Jun 30, 2016 11:41 am #50003 Hi,
if you allready make use of deep sleep then the most problematic thing is your choice of board.
The NodeMCU has a very bad (current wise) 3.3V regulator and USB/serial chip.

You can try to power the NodeMCU via the 3.3V pin to cut out these two or move the "final" product to a standard ESP. For use on breadboard consider using an ESP-201.

In general you can power from a Li-Ion (LiCoO2) cell via an ldo regulator and check vcc (use system), if it drops under 2.8V consider the cell empty and go to deep sleep without wakeup time.

Or directly power from a LiFePO4 that has an acceptable 3.65V max and allmost constant 3.3V over more than 80% capacity; switch off as above.

For an estimate consider the esp 8266 drawing ~ 50µA in deep sleep, the flash chip ~15µA, the BMP180 ~4µA, the DHT11 ~60µA in standby. For the time of measurement I used an estimate of ~150mA for about 5s for the whole device. This gives ~ 1mA average with one measurement + upload to TSP @ 15min.