Lithium rtc battery HP Compaq  Real Time Clock Battery New Battery for: HP Business Solutions Notebook [sb] HP NC6120 Series   We are delighted that you have taken the time and interest in viewing this auction for a new cmos bios battery for several of the HP Compaq Armada and Evo models listed. The peformance of a new cmos battery will bring back the power computing to your notebook that has lost it's date/time sequence. This item is the same battery type as the one that's in connected to your HP Compaq models listed above, inserted into a small connector that's on the motherboard. This is not the main battery that subs for the AC/DC adapter brick, rather the purpose of this battery is solely for the firmware of the bios chip to maintain date/time clock functions while the notebook is not in use.