Tutorial for MKR IoT Carrier Battery

I bought the "Explore IoT KIT" with the Arduino MKR WIFI 1010 and the MKR IoT Carrier a couple weeks ago and noticed that the Carrier can be powered via a battery (18650 Li-Ion).

However, I could not find any tutorial, about how to set up the energy-supply via the battery.

Is it only plug and play or do I have to write a special piece of code to charge the battery via the arduino?

I would be grateful for any help or tutorial about this matter.

This is fully automatic. The charger controlller is internally connected via I2C so can be programmed.
Thus everything is automatic and i don't know of a lib for that chip and it might be harmful to write crab into it's register, the only usefull code in my opinion is:

int Batt_int = analogRead(ADC_BATTERY);
    // Convert the analog reading (which goes from 0 - 1023) to a voltage (0 - 4.3V):
    float Batt_int_v = Batt_int * (4.3 / 1023.0);