Replacing laptop CMOS battery.

[#1]

If I replace the battery am I correct in thinking that the laptop should then boot up with the default bios configuration? Which parameters are lost when the old battery is removed?

[#2 · Accepted solution]

@nozzer - Everything you have changed from the defaults in the BIOS, including time, enable / disabling of NICs, boot order etc. Having said that the only thing you will need to change after replacing it will be the system time.

[#3]

@Anonymous  Thanks. So the basic configuration is stored in the bios chip. I think I can manage to change the time! 

[#4]

You're welcome @nozzer - But not wanting to teach you to suck eggs here but replacing the battery in a laptop isn’t the easiest of things to do and by no means as easy as a PC. If you can, start by getting a service manual for it online, it will make the task so much easier, and allow you to get (order) the correct battery and gather any specific or odd tools needed to get it apart.

[#5]

Yes, the biggest problem is going to be getting at it! It's tucked away on top of the motherboard under the laptop cover, which means keyboard etc has to come off. I shall have a stab anyway.

[#6]

"Name and Shame" the manufacturer

The more enlightened put the CR2032 cell somewhere (relatively) accessible; such as a tray in battery compartment or (as per my Toshiba) under the same cover as the memory/HDD.

Phil

[#7]

It's a Clevo P170EM, about five years old (hence the battery), assembled by PCSpecialist. Generally a nice machine actually. I got a copy of the service manual and there is no mention of changing the CMOS battery, just a picture of where it is. Not even a battery type, so I will have to wait until it's out to identify it.

[#8]

As @PeeGee says, chances are it's a single CR2032 or multi-pack of same, but best to wait till it's open, just in case it not of the 'normal' variety.

[#9]

A small minority of computers do not use the default BIOS settings.  I presume this happens when the manufacturer makes some late-stage change.  If you want to be ultra-cautious it might be possible to back-up the BIOS settings before replacing the battery.

That said, you usually only know the CMOS battery is flat when the machine loses its settings so if you have survived that then there is nothing to worry about.

[#10]

I had an HP laptop moons ago, tried the cmos battery removal and the bios was still password locked when i rebuilt it.

Try it but don't pin your hopes on it.

[#11]

Good luck with replacing the CMOS battery, nozzer - I had to write off my brother's Asus laptop when the battery died in that. Absolutely impossible to get at, despite dismantling most of the computer - the battery seemed to be on top of the motherboard, underneath the keyboard. I've never seen so many little screws, all of different sizes, although I did manage to re-assemble everything with none left over! But still a write-off, nonetheless.

[#12]

Hey! That's where the battery on this is! 

I might leave it until it's absolutely necessary.