BIOS battery query

CurlyWhirly · 4 Feb 2006 at 16:46

I have a query to do with the BIOS battery.
Would I be right in thinking that the battery only provides power for the BIOS settings (including the time) while the PC is off or does the battery also provide power while the PC is on?

I am just wondering if, generally speaking, the battery lasts longer if you have your PC on for most of the day as mine normally is.

I do realise that most PC's are upgraded before the BIOS battery ever goes flat but I'm just curious :rolleyes:

CurlyWhirly · 4 Feb 2006 at 19:13

Scream said:
A few minutes charge of the battery would last for a good while but like any other rechargable battery, its good to keep recharging it.

So are you saying that when the PC is on that the motherboard is recharging the battery then?

If so, I had no idea that this was the case as I just thought that the battery keeps using it's power reserves until it eventually gets too drained and has to be replaced.
Interesting indeed!

Thanks for replying BTW

CurlyWhirly · 4 Feb 2006 at 19:26

lordedmond said:
look in your manual and google the batt. no. to find out

Thanks.

It doesn't say in the manual and to be honest it isn't important enough to me to physically inspect the motherboard!

Let's say for instance that the battery has a 5 year life, would it lose it's charge more quickly if the PC was only used occasionally as opposed to being in regular use?

That's what I was trying to find out but I didn't word the question properly

CurlyWhirly · 4 Feb 2006 at 19:43

Thanks.

I now know that CMOS batteries are not rechargeable, so I assume that the BIOS settings are powered by the battery even when the PC is on then?

Also would I be right in thinking that the PC would still boot even if the CMOS battery was flat?
The clock time would obviously be wrong but what about the actual BIOS settings?
Would they revert to default settings?

CurlyWhirly · 4 Feb 2006 at 19:52

Jeff Crawly said:
Constantly flashing the BIOS and changing settings in the BIOS will run it down quicker as these functions draw more current from the CMOS battery

Crikey, I go into the BIOS quite frequently to have a nose!
I didn't know that it runs the battery down quicker! :eek:

I am upgrading to a 64 bit PC within the next 12 months so it doesn't really matter to me but as I intend on selling this PC cheaply (as it's over 3 years old), I just wondered whether the PC would still be able to boot if the CMOS battery went flat, hence my query.

CurlyWhirly · 5 Feb 2006 at 01:52

lordedmond said:
if your worried they are not more than a fiver just replace it

I wasn't that worried just curious as to whether the PC would still boot with a flat CMOS battery!

CurlyWhirly · 5 Feb 2006 at 04:13

Steves_pc said:
but should still boot into windows assuming the 1st hdd is the bootable one.

Thanks.
That's all I needed to know.

CurlyWhirly · 3 Apr 2006 at 14:29

I have just read this thread and also this post:

manveruppd said:
Clearing the CMOS doesn't make you need a reflash, it just resets the BIOS to defaults. It's actually non-volatile - the battery is just there to maintain the clock working when the computer's off. I've had PCs whose CMOS battery died and they were still working, they just always displayed the year as 1980 no matter how many times I fixed it.

I'm curious

When your CMOS battery dies do you just lose the date and time settings or are other BIOS settings affected as well :confused:

I thought that the BIOS settings were also affected.

CurlyWhirly · 3 Apr 2006 at 15:03

Thanks lumocolor