ESP8266 Community Forum

- Tue Oct 20, 2015 7:51 am #31827 Hi, have a look at this https://www.pololu.com/product/2122
It would give you best useage of your batteries as the input is from 2.7V to 11.8V and it has an enable or shutdown (SHDN) pin.
The text says:

Connections

The step-up/step-down regulator has four connections: shutdown (SHDN), input voltage (VIN), ground (GND), and output voltage (VOUT).

The SHDN pin can be driven low (under 0.4 V) to power down the regulator and put it in a low-power state. The quiescent current in this sleep mode is dominated by the current in the 100k pull-up resistor from SHDN to VIN. With SHDN held low, this resistor will draw 10 µA per volt on VIN (for example, the sleep current with a 5 V input will be 50 µA). The SHDN pin can be driven high (above 1.2 V) to enable the board, or it can be connected to VIN or left disconnected if you want to leave the board permanently enabled.

Lokking at the schematic https://www.pololu.com/picture/view/0J5668
R6 (100k) is just a pull up resistor for SHDN. If you can supply a voltage of more than 1.2V to this pin from your wake up source then the resistor is not needed and could be removed. That inturn would give a sleep current of 0.
This could also handle recharging of the batteries - a solar top up?

Last edited by Barnabybear on Tue Oct 20, 2015 8:03 am, edited 1 time in total.

- Tue Oct 20, 2015 7:53 am #31829 The battery voltage seems to drop rather quickly, does this indicate that the battery drains out?
Would be interesting to find out how long this can last on a '2000mAh' battery?

Thanks for the posting!

Greg

- Tue Oct 20, 2015 8:07 am #31833

The battery voltage seems to drop rather quickly, does this indicate that the battery drains out?
Would be interesting to find out how long this can last on a '2000mAh' battery?

Thanks for the posting!

Greg

It was not fully charged at all, just a random test to see how long will go 'as it is'. Now on day 2.
From 4.02V to 4.001V now is a uite decent voltage drop in this situation.

When drained out I will fully charge it and run another test if is interest about.
It's a small one, 4.8x3.8x0.5 cm, real, around 380-400mAh.

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- Tue Oct 20, 2015 10:41 am #31841

The battery voltage seems to drop rather quickly, does this indicate that the battery drains out?
Would be interesting to find out how long this can last on a '2000mAh' battery?

Thanks for the posting!

Greg

I think the scale on that graph can lead to the wrong conclusion: even if the voltage has barely moved, it appears as a big drop, because the lower part of the graph is not at 0v.