ESP8266 Community Forum

- Thu Oct 15, 2015 4:34 am #31407 I power the module from a 3.7 v LiPo connected to the charging module (this one: http://www.aliexpress.com/item/Micro-US ... 26505.html). The problem is: it supplies 4.2 v and my ESP-07 doesn't work with it. I could make a voltage divider to cut it down to 3.3, but then when the charging module is disconnected and the battery powers ESP-07 it would cut the voltage too much.
Googled it and found LD1117 https://www.adafruit.com/products/2165. But I'm not sure if it won't cut the batteries voltage.
The perfect solution would be a regulator that holds steady 3.3 volts both when the charger is connected and the circuit gets 4.2 volts and when the circuit is battery powered (from 3.7, lowering down to 2.8 or something).
What would you suggest? Thanks!

- Fri Oct 16, 2015 5:34 am #31505 That LD1117 regulator would work ok, or you can get made up modules with regulator and its capacitors like this or this.

An issue is that those types of regulator have quite a high quiescent current - a few milliamps - so will drain the LIPO even if you're using sleep modes on the ESP. If thats important to what you're doing then something like a MAX604 or MCP1700 have much lower quiescent current.

- Fri Oct 16, 2015 6:54 am #31513 I was not successfull with well decoupled LD1117or AMS1117 driven with LiPo
Too big 'drop out voltage' (around 1V) !!

Better success with RichTek RT9167 used on ElectroDragon's adaptators for ESP12
I'm logging LiPo discharge voltage and have first problem around 3.6V LiPo voltage
Strong current changes when ESP awakes from deep-sleep cause short drop out (0.3V) voltage on regulator's output
Some drop out put ESP module in strange mode, ESP temperature arise....
Must put ESP in 'no wake' deep-sleep when LiPo voltage is 3.65V

SPX 3919 as used on Adafruit's Huzzah boards seems also OK according to their datasheet

3.0 V low drop regulator LiPo driven ?
LiFePo4 driving ESP modules without any regulator ??

Attachments

LiPo-ESP.png (45.87 KiB) Viewed 11039 times

- Fri Oct 16, 2015 9:42 am #31530

I power the module from a 3.7 v LiPo connected to the charging module (this one: http://www.aliexpress.com/item/Micro-US ... 26505.html). The problem is: it supplies 4.2 v and my ESP-07 doesn't work with it. I could make a voltage divider to cut it down to 3.3, but then when the charging module is disconnected and the battery powers ESP-07 it would cut the voltage too much.
Googled it and found LD1117 https://www.adafruit.com/products/2165. But I'm not sure if it won't cut the batteries voltage.
The perfect solution would be a regulator that holds steady 3.3 volts both when the charger is connected and the circuit gets 4.2 volts and when the circuit is battery powered (from 3.7, lowering down to 2.8 or something).
What would you suggest? Thanks!

Hi Alex, I'm facing the same problem. At the moment I have just placed a 1N4005 diode in series with the ESP8266.
I'm using an IRC18650-22p 2200mA Li-ion battery that charges at 4.17V. I get the following voltages:
Battery on charge = 4.17V
ESP off or in deep sleep = 3.89V
ESP on = 3.39V
Obviously this is not ideal as in deep sleep the ESP does not draw enough current to cause the diode to drop its normal working voltage. I'm sure there is a better suited diode about.
In theory with a voltdrop of 0.7V accross the loaded diode the battery should be able to discharge to 3.7V and still supply 3.0V to the ESP.

WARNING to anyone reading this. This example supplies a voltage in excess of the manufacturers specification. Just because it works for me does not mean it will work for you - you try at you own risk.