CMOS battery?

richardj · Post by **richardj** » Sat Sep 18, 2004 10:34 pm

Does a PC have to have a functioning battery to enable it to recognize the drives?

Mine crashed on reboot and then would not recognize any of the drives. After many hours and much agony, I removed the battery & disconnected the power (to clear the cmos) then hooked everything back up and it returned to normal. I believe the battery was not making good contact. I know the battery retains the cmos info when powered down, but if its out ,will the cmos loose the ability to recognize the drives even if the AC power is on?

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Red Squirrel · Post by **Red Squirrel** » Sat Sep 18, 2004 10:41 pm

Yes and no. The drive information (cylinders, heads etc) is stored in the cmos and it defers from drive to drive, and size. So the only way for it to boot is that it has this information, so with a dead cmos battery you need to go in the bios and reset this information (usually doing an autodetect will do the trick). I had a PC that I had to do that every time I turned it on.

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richardj · Post by **richardj** » Tue Sep 21, 2004 2:00 am

I understand that, but

with the battery out & the CMOS set on automatic (for drive recognition)

it still would not boot up.

Each drive came up "not installed".

As soon as I reinstalled the battery & pushed the contacts down really hard,

it recognized all the drives & I've had no problem since.

It has a PC CHips

motherboard.

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Red Squirrel · Post by **Red Squirrel** » Tue Sep 21, 2004 3:35 pm

Yeah since you need to reset it each time without shutting off the computer.

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richardj · Post by **richardj** » Tue Sep 21, 2004 11:22 pm

The thing is that with the CMOS set on automatic & the battery in it recognizizes the drives

if I take the battery out it won't recognize the drives.

What I'm trying to figure out & never heard of is:

Why , when you have AC power on

do you need the battery in place on order for the Bios to recognize the drives?

Archived topic from Iceteks, old topic ID:2655, old post ID:21861

Red Squirrel · Post by **Red Squirrel** » Wed Sep 22, 2004 8:36 am

The default is probably to not detect automaticly, so that's why even though you set it there, the battery is dead so it uses default settings when it boots.

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richardj · Post by **richardj** » Wed Sep 22, 2004 10:11 pm

I know we're beating this to death-BUT

The default is to detect automaticly, as this is what the CMOS defaults to when you yank all the power.

I can set the bios to autodetect the drives.

When the battery is out it detects nothing & says "not installed"

When I reinstall the battery, it detects them fine.

So, the question still is why does the CMOS )or Bios) need a battery to detect the drives when AC is present?

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Red Squirrel · Post by **Red Squirrel** » Wed Sep 22, 2004 10:21 pm

Hmm I never had that proble with my situation but maybe your bios is different. So I guess the best route to go is to just replace it with a new battery. From what I heard as long as you have the right voltage your safe so if you can't find the same kind just get one with the right voltage.

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