Question on PC & Peripherals:

I would like to find out if the CMOS battery in my PC recharges itself when the computer is switched on. Usually when the battery is weak, it causes problems particularly in booting up the PC. How can I prolong the life of the CMOS battery? Does leaving the PC switched on have a charging effect on the CMOS battery or does it damage the cell? How long does CMOS batteries generally last?

Submitted by CNET Asia reader, via email

Answer:

The CMOS battery is a non-rechargeable Lithium cell which powers the chipset when the machine is off. This prevents your mainboard's system time and BIOs settings from resetting each time the power is switched off. In other words, leaving the PC switched on will not charge the CMOS battery, neither will it damage the cell.

When the battery becomes weak, you just have to replace it. The cell normally lasts for at least a couple of years and, most likely, by the time you need to change it you would already be considering upgrading your mainboard anyway.