HP M21797-001 RTC battery is a spare part for HP systems. It backs the real-time clock circuit, supporting retention of system date, time, and noncritical data in RTC battery-backed CMOS memory.
The battery connects to the system board by a cable. During service, the cable is disconnected and the battery removed; installation follows the same procedure in reverse. This part is for servicing the RTC battery identified by M21797-001.