View Full Version : BIOS Battery
06-12-2001, 03:18 PM
I know I have to change the BIOS battery in my computer, a project that I'm not looking forward as most of my forays inside the beige box end in frustration and/or tragedy. I know it needs changing because it won't keep the time or date correct when I turn if off, much to the chagrin of some of my e-mail correspondents when I forget to reset it. Besides this, though, I've really noticed no problems with this beast as a result of having a dead battery except for the time problem. So, does the BIOS battery do anything besides keep the time updated? And if so, why am I not expereincing any other problems? Or am I just to stupid to realize them?
06-12-2001, 03:34 PM
Yes indeed the BIOS battery keeps other info current. The first sign that it's end of life is near, is that the time quits moving when one shuts the machine off, next the clock resets to a predetermined date. (01-01-80 is typical) The next thing to go is very bad for the computer, as it's the configuration of the HDD, and other motherboard settings.
Well I suppose that's not very bad for the computer, but it is for the operator. (In which case it can be VERY bad for the computer)
Now you'll probably hear that many new motherboards auto-detect the hard drive, so that's no longer an issue. Rest assured there are enough other things the battery keeps current,(no pun intended) it's not a good thing to lose all that data. Prior to replacing it, I'd note every setting in the BIOS. (There used to be applications that do this, but I know of no recent ones.)
FWIW, my first paragraph is what a "good" motherboard does. A bad one doesn't give any warning.
06-12-2001, 04:58 PM
just a nitpick:
The CMOS chip is the chip that required the battery. the BIOS is hardcoded and will not lose information if the battery goes dead.
You man continue now.
06-12-2001, 05:47 PM
Changing the BIOS battery is among the simplest and easiest things you can do. In most PC's made in the past 3-4 years the BIOS battery is a quarter sized 3 volt lithium battery that can be removed (gently) from the spring clip holding it to it's seat on the motherboard and taken to Radio Shack or a battery store kiosk in the mall for replacement. Unless your battery is unusually thick and needs special ordering RS (or any electronics store) should have the battery in stock. In older PC's (older Compaqs et al) the battery can be a special (and somewhat expensive) lithium package or simply a holder with 4 AA alkalines.
Do write down your BIOS setting parameters as you will have possibly have to re-enter some of them after replacement.
If you want to have the battery at the ready before replacing simply call your PC manufacturer or look at the owner's motherboard manual and it should have the battery type listed. Make sure you remember what side the battery + and - were facing when you remove it so you can replace it with the correct polarity.
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