Ask Our Experts: Dead Battery Blues

Advice on extending the life of your laptop's CMOS battery.

Tom Mainelli

I spent $2000 on a notebook and seven years later the $3 CMOS battery died, necessitating a $300 repair. Why can't manufacturers make the battery user-replaceable?

Vern Wolfe, via e-mail

Senior Editor Tom Mainelli responds: Notebook vendors I talked to say that the average CMOS battery, which powers a tiny bit of memory for storing vital system data when there's no other power source, will last anywhere from five to seven years. The cramped confines of most laptops often make it impractical to put the coin-size CMOS battery in a more accessible spot, and vendors note that the vast majority of users replace their notebook every three to four years anyway. To ensure your CMOS battery lives a long, full life, try not to let your notebook's regular battery run completely out of juice.

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