HP L17255-001 RTC battery is a replacement part for the real-time clock function in a compatible HP computer. HP’s service guide identifies this exact part number as the RTC battery spare part.
The RTC battery backs up CMOS configuration memory, which stores the system date and time along with other noncritical data. This helps retain those settings when the computer is not running from its main power source.
The guide shows the battery connected to the system board by a cable and released from its position inside the computer during removal. It is intended as a service replacement for the RTC battery specified by HP.