CMOS battery failed

[agstanesby]

On power up the following message is displayed:

CMOS checksum error - Defaults loaded
CMOS battery failed

This error occurs when the PC is swithed off for several hours (overnight for example) but doesn't occur after the PC has been powered on for several hours (during the day for example).

I would normaly change the battery but there is no external battery on the motherboard.

My question is, what would be the best way to remedy this failure?

[joelen]

If there is actually no battery on the motherboard itself- you probably have noe that is built into the BIOS chip--- quite expensive to replace unless you can find another moard with one and switch it--

What motherboard?

[Milenko]

There has to be a battery there somewhere. Whenever you find it, it needs to be replaced, cause it's dead. Some older motherboards had the battery soldered directly onto the board, in which case it'll be fairly tought to replace cause you'll have to remove and re-solder the battery. Some of those boards also had pins on the board to connect an external battery that you are probably more familiar with. Look at the board closely with all the cable unhooked so you can see everything well. Somewhere are the battery there should be a set of pins, usually four, but with one missing (in order to key the plug). There's where yer external battery will go (if that plug exists).

[joelen]

We actually used to sell a MB with no external battery-- it really was built into the BIOS chip... it's really fun for our new techs who get someone on the phone who has the same error you're getting--- the just won't believe tha caller- that there really is NO battery!

I don't recall the make model or i would post it--- i'll talk to our other bench tech when he comes in and try and find a link....

[Mr_Miyagi]

must be a fairly old machine...

incidentally, some mobos allow you to connect an external "normal" battery (as an add-on), there maybe a connector somewhere that allows this. check the mobo manual. this is obviously a bit of a bodge-job. but hey? if it solves it.

[Platypus]

If there is a black box with a name such as Dallas, Houston Tech or Odin on it, it is the Real Time Clock/CMOS/Backup Battery.

See this topic:
http://forums.windrivers.com/cgi-bin...c&f=1&t=001358

Ruslan's post has some links that could be helpful.

[agstanesby]

Originally posted by Platypus:
If there is a black box with a name such as Dallas, Houston Tech or Odin on it, it is the Real Time Clock/CMOS/Backup Battery.

See this topic:
[URL=http://forums.windrivers.com/cgi-bin/forum3/ultimatebb.cgi?ubb=get_topic&f=1&t=001358]http://forums.windrivers.com/cgi-bin/forum3/ultimatebb.cgi?ubb=get_topic&f=1&t=001358[/UR L]

Ruslan's post has some links that could be helpful.

Thanks to everyone who replied! and thanks to Platypus whos hit the nail on the head.

It was 'hiding' under the power connections
and its in a socket!

Thanks again!