The RTC battery is charged as soon as a power source is connected; battery, power supply, or vehicle adaptor
The RTC battery runs approx. 8,000 hrs until it is empty, i.e., a little less than 1 year.
It takes about 50 hours to recharge the battery, as it charges at a minimal current.
If the RTC battery is empty, the default state is restored, i.e., all BIOS settings as well as the time and date must be reset.
If a BIOS password is stored, it is NOT deleted and must be entered to configure any settings.