ESP32-H2-DevKit-Lipo - Battery measures

[lmerckx]

Hello,

I have the Olimex ESP32-H2-DevKit-Lipo and a battery 3.7V 1400mAh (JA-803450P) and try to measure the voltage of the battery to compute the percentage of the battery but I receive strange results.

I soldered jumpers BAT_SENSE_E and PWR_SENSE_E1 as explained in the manual and tried the example code to read pins 25 (POWER_SENSE) and 2 (BATTERY).

It works perfectly for the POWER_SENSE: testing with USB connection or battery only, it returns me the expected result.
But I have issues when trying to read the battery voltage.
- when connecting USB only: I always receive the analog value 652 or 653 (so 3716.40 mV or 3722,10 mV after multiplying by 5.7).
- when connecting both USB and battery: most of the time, I receive the same value but once on 10 measures I receive another value: 667 or 668 (so 3801.90 mV or 3807.60 mV). -> I suppose this to be the real measure of the battery because the value slightly increase with time.
- when connecting with battery only: again, I think I receive only the value 652 or 653. To be honest, I'm still not sure of that because I don't have the serial connection to debug and must rely only on my Zigbee report.

Is it the normal behavior of the pin ? I check my solder twice with multimeter and it seems quite good.
Any idea ?

Thanks in advance.

[LubOlimex]

Seems fine to me. It just takes a lot of time to fully charge and discharge. The board is set to charge with only 100mA. Let it charge for a couple of hours and compare the value again. The JA-803450P should go up to 4.2V when fully charged. Alternatively let your software run only on battery and check the progress without connecting the USB to it.