For the current supply of the terminal Lithium-Ion batteries are used. A rechargeable, not exchangeable by the user, backup battery secures the program memory if the capacity of the main battery is low or during the change of the main battery. The backup battery is charged by the main battery.
4,0 hours (Cradle)
13- 25 hours
10 minutes for RAM
Further information, especially about calculating the running time can be found in the Hardware Manual.