Flat BIOS Battery - any problems?

Overread · Dec 19, 2011

Ok so lets say the battery in the motherboard goes dry for an extended period of time (lets say weeks). Is there any risk to the computer or computer data itself? In short would one come back to a pile of parts that won't work or simply have to reset the time in the BIOS to get things running as normal?

camz · Dec 19, 2011

Your CMOS BIOS battery is supplying power in order to maintain the data stored in your bios. Having it depleted out on you when your PC is plugged probably won't do anything. However, if you unplug your computer with a depleted bios battery, your bios settings will reset back to its default settings. Your bios has two sources of power, the bios battery and the power from the wall. If you take out both of those, the bios will default. One source has to supply power to the CMOS in order to maintain its state. So your time stamp, boot sequence and others will probably change. The key is the boot sequence, if it resets it will probably try to boot form a disk drive, so your OS platform won't launch as it's stack pointed from your hard drive.

If you haven't already, take down the profile settings of your operational BIOS before changing out the battery. If your bios resets, then you have your settings down in paper. If you want to go hardcore, reflash your bios to where the default settings are your operational settings so in case the bios resets, it resets to an operational state.

No harm no foul should happen to your hardware if the bios battery goes out on you - just a matter of software settings and like you said the time stamp.

unpopular · Dec 19, 2011

If your bios battery is dead, then it's probably a pretty good sign that your computer is getting old. Once charged, these batteries should last years before they drain completely and a decade or more before they're dead entirely.

Besides, isn't most BIOS data stored on flash memory these days?

camz · Dec 19, 2011

On the older ones I don't think you can charge the bios battery. I've seen alot of motherboards and it's supplied probably by a CR2032 which I don't think the market includes rechargeable batteries on their boards.

Yes if they board is up to spec if should run for years, atleast 5 good ones.

Edit: Unless you meant charged, as in new battery.

kamerageek · Dec 19, 2011

Your personal data is all stored on your hard disk drive. The data on that disk is easily recoverable even if the computer becomes inoperable. The worst thing that can happen in the case of a dead CMOS battery is that your basic hardware settings going away.

A good PC repair shop can get you running again for a few dollars.

unpopular · Dec 19, 2011

camz said:
On the older ones I don't think you can charge the bios battery. I've seen alot of motherboards and it's supplied probably by a CR2032 which I don't think the market includes rechargeable batteries on their boards.

Yes if they board is up to spec if should run for years, atleast 5 good ones.

Edit: Unless you meant charged, as in new battery.

Those old button battery types I haven't seen in eons. Usually they use some kind of rechargeable canister-type battery now, and at least on a Mac, they've been using flash memory which doesn't need the constant power source. I'd imagine newer PCs also use flash memory for BIOS parameters.

Trever1t · Dec 19, 2011

I have an old Vaio that has a dead cmos battery...it's a pita because the clock is always off and some programs rely on time but other than that it's ok. I just have to set the time when I go to use it, which is rarely (it's a 3rd backup)

Overread · Dec 19, 2011

Thanks for the input all - its put my mind at rest since I couldn't get hold of a replacement and I'm heading off home for Christmas.

cgipson1 · Dec 19, 2011

camz said:
Your CMOS BIOS battery is supplying power in order to maintain the data stored in your bios. Having it depleted out on you when your PC is plugged probably won't do anything. However, if you unplug your computer with a depleted bios battery, your bios settings will reset back to its default settings. Your bios has two sources of power, the bios battery and the power from the wall. If you take out both of those, the bios will default. One source has to supply power to the CMOS in order to maintain its state. So your time stamp, boot sequence and others will probably change. The key is the boot sequence, if it resets it will probably try to boot form a disk drive, so your OS platform won't launch as it's stack pointed from your hard drive.

If you haven't already, take down the profile settings of your operational BIOS before changing out the battery. If your bios resets, then you have your settings down in paper. If you want to go hardcore, reflash your bios to where the default settings are your operational settings so in case the bios resets, it resets to an operational state.

No harm no foul should happen to your hardware if the bios battery goes out on you - just a matter of software settings and like you said the time stamp.

^^^ This!