In AT Commands Manual rev 004 for OS 6.61:
The section on the battery charging command AT+WBCM doesn’t make clear that when a charger is plugged in, you have to turn the charger on again. My assumption from reading that section was that you enabled the charger, and it would charger when ever the battery needed to be charged and the charger was present. It turns out that you need to send a AT+WBCM=1,2 or similar every time the charger in plugged in.
Also, when an “unusual voltage or temperature” is reached, it is unclear whether the charger will be turned off or not.