A thermistor can be connected to the ESP32-S3 PowerFeather. This enables the charger IC to give a readout of the battery temperature, and to reduce or cut-off charging current when certain temperatures are hit.

Thermistor header pin location

The graph below shows the relationship between the max charging current % and the temperature.

Max charging current % and temperature relationship

If the user sets max charging current to 1000 mA for example, the charger IC is only able to allow charging to go that high if the battery temperature is within 15 C and 35 C. Outside of this temperature range, the max charging current is capped at a certain percentage, illustrated in the table below:

The following pictures show this in action (potentiometer is used instead to simulate a thermistor):

Charging current from 15 C - 35 C: ~ 1 A

Charging current from 10 C - 15 C: ~ 400 mA

Charging current from 0 C - 10 C: ~ 200 mA

No charging current below 0 C

Charging current from 35 C - 40 C: ~ 400 mA

Charging current from 40 C - 50 C: ~ 200 mA

No charging current above 50 C