The nPM1100 Power Management Integrated Circuit (PMIC) implements thermal protection based on battery temperature via the NTC pin.
When using a battery pack with an integrated thermistor, battery connector P2 should be used and header P5 should be left unconnected.
When using a battery pack without an integrated thermistor or when using connector P3, P6, or P8 pin 2, a 10 kΩ onboard resistor can be used instead of a thermistor by shorting P5 pin 2 and pin 3.
Optionally, a thermistor can also be mounted onboard via R19 footprint. P5 pins 1 and 2 must be shorted together to connect the thermistor.
If there is no NTC in the battery pack and the P5 header is not adjusted, charging will not occur and the CHG LED will not light up.