Had to press any key to reset CMOS when dad's laptop died.

Thready · Oct 27, 2025

My dad's laptop has been plugged into his desk's outlet for years, only removed from the charger to move something, but never used off the charger. Last night his charger stopped charging and we didn't realize until his pc gave a low battery warning and went out. I plugged in my mom's charger and the charging light came on, so it was obviously his 45 watt charger that went out. When it came back on, it told me the CMOS had to reset and press any key to continue. Is that a bad CMOS battery and the CMOS chip was using the charger to stay on? Is a CMOS battery just a 2032? If I open the laptop and replace the CMOS battery then that message won't come on anymore if my dad's laptop loses power right? Or is there something else completely going on? The only reason I can think of for the CMOS going out when the computer goes to 0% is the CMOS battery is depleted and it was using the charge from the wall to stay on.

dacrone · Oct 27, 2025

Thready said:
My dad's laptop has been plugged into his desk's outlet for years, only removed from the charger to move something, but never used off the charger. Last night his charger stopped charging and we didn't realize until his pc gave a low battery warning and went out. I plugged in my mom's charger and the charging light came on, so it was obviously his 45 watt charger that went out. When it came back on, it told me the CMOS had to reset and press any key to continue. Is that a bad CMOS battery and the CMOS chip was using the charger to stay on? Is a CMOS battery just a 2032? If I open the laptop and replace the CMOS battery then that message won't come on anymore if my dad's laptop loses power right? Or is there something else completely going on? The only reason I can think of for the CMOS going out when the computer goes to 0% is the CMOS battery is depleted and it was using the charge from the wall to stay on.

1) yeah, its a coincell battery. pretty sure its 2032 but i havent replaced one in some time, so not 100% positive. i'd google the exact model to be sure (or just open it up).

2) being on the charger for that length of time... you may want to check the laptop battery too. it may be swollen by now

Thready · Oct 27, 2025

dacrone said:
1) yeah, its a coincell battery. pretty sure its 2032 but i havent replaced one in some time, so not 100% positive. i'd google the exact model to be sure (or just open it up).

2) being on the charger for that length of time... you may want to check the laptop battery too. it may be swollen by now

I thought about checking the battery for swelling but I don't know what the threshold between normal and swollen is other than the extreme examples I've seen on social media. I assume if I press my finger into it and it has any give whatsoever then it's swollen?

dacrone · Oct 27, 2025

Thready said:
I thought about checking the battery for swelling but I don't know what the threshold between normal and swollen is other than the extreme examples I've seen on social media. I assume if I press my finger into it and it has any give whatsoever then it's swollen?

you'll know when you see it lol. if its still pretty flat, you're good. if its swollen (especially after that length of time) it would most likely stick to the bottom panel when you try to take it off, and/or be a tight fit when you try to put the bottom back on.

Ghot · Oct 27, 2025

@Thready

If it IS a CR 2032 (which it probably is), they cost about $6.
For example... CR 2032 batteries x4 $5.97

But you can get them anywhere. Drug stores, Walmart, Home Depot, Jewelry stores, etc.

On a desktop computer you can just pop out the old one and pop in a new one.

On a laptop... who knows. I don't.
All that a CMOS battery does, is make it possible for the BIOS not to forget it's settings.

Here's ten points for filling out your computer specs. We like it when you do that.

Thready · Oct 27, 2025

Ghot said:
@Thready

If it IS a CR 2032 (which it probably is), they cost about $6.
For example...

CR 2032 batteries x4 $5.97

On a desktop computer you can just pop out the old one and pop in a new one.

On a laptop... who knows. I don't.

Here's ten points for filling out your computer specs. We like it when you do that.

Thank you for the points! I still have too many hard drives to count. I let them die all the way before replacing them, because I have enough backup to run a small country's entire economy

Thready · Oct 27, 2025

dacrone said:
you'll know when you see it lol. if its still pretty flat, you're good. if its swollen (especially after that length of time) it would most likely stick to the bottom panel when you try to take it off, and/or be a tight fit when you try to put the bottom back on.

oh ok so it would be obvious that it's bad

Ghot · Oct 27, 2025

Thready said:
oh ok so it would be obvious that it's bad

If it's bad, the BIOS will forget all the settings, and that "might" generate a "reset BIOS to defaults" message.

Usually, if the CMOS battery is bad, the computer won't do anything, it will just sit there like a brick.
Then when you replace the battery, you'll have to rest a few things in the BIOS.
How many things, all depends on the manufacturer.

I would probably just call the laptop manufacturer and ask about that message you got.

On a regular desktop motherboard, they come set to defaults, and the builder has to pick and choose what settings to set in the BIOS.
On a laptop, the laptop manufacturer chooses those things.

Sometimes a loss of power can cause a glitch in the BIOS, and you might also get a message like that.
On a desktop motherboard, the message is usually something like... Press F1 to enter setup.
Setup in this case is the BIOS.

Helmut · Oct 27, 2025

It will probably be a standard 2032 3v Lithium cell, but on some Laptops it is welded to flying leads, shrink wrapped and a plug, those you won't find stocked in normal stores, Amazon will have them.

The BIOS settings would have reset to safe defaults, not a problem on a Laptop as that probably not changed since purchase.

Spunk · Oct 27, 2025

What is the Make and Model # of the laptop?
If it was a desktop the CMOS battery would be CR 2032 coin looking watch battery available in any drug store or store that sells electronics.
But depending on the Manufacturer, the CMOS Battery on a laptop can be a coin size batter that has a wire on it that has to be plugged into the motherboard.
As stated, many new laptops have the CMOS battery soldered onto the motherboard and are not replaceable.

itsme1 · Oct 27, 2025

In my Dell laptop I have a classic CR2032 3V lithium button battery like a desktop. It is removed like a desktop.

mort · Oct 27, 2025

I just changed several Laptop CMOS 2032's (older Lenovos and a Dell) like this one with a small 2 pin connector:

Even a new ThinkPad had this type. Never seen a CMOS battery soldered to the motherboard, that can't be true!

bobkn · Oct 27, 2025

mort said:
(snip)

Even a new ThinkPad had this type. Never seen a CMOS battery soldered to the motherboard, that can't be true!

According to Copilot, some thin/light laptops have soldered-in CMOS batteries. Replacing one would be a repair.

Jeepers. Planned obsolescence to a high degree.

Steve C · Oct 28, 2025

Very likely you need a new CR2032 CMOS battery. Accessibility varies. My 2014 Dell laptop had the CMOS battery covered by part of the plastic frame (daft design!) so I very carefully cut an access window.

Thready · Nov 9, 2025

Ghot said:
If it's bad, the BIOS will forget all the settings, and that "might" generate a "reset BIOS to defaults" message.

Usually, if the CMOS battery is bad, the computer won't do anything, it will just sit there like a brick.
Then when you replace the battery, you'll have to rest a few things in the BIOS.
How many things, all depends on the manufacturer.

I would probably just call the laptop manufacturer and ask about that message you got.

On a regular desktop motherboard, they come set to defaults, and the builder has to pick and choose what settings to set in the BIOS.
On a laptop, the laptop manufacturer chooses those things.

Sometimes a loss of power can cause a glitch in the BIOS, and you might also get a message like that.
On a desktop motherboard, the message is usually something like... Press F1 to enter setup.
Setup in this case is the BIOS.

The laptop is a cheapo from 3 years ago so I probably wouldn't get any support for it. It might have happened because of what you said about it losing power. My dad must not have noticed it was dying until it was all the way dead and by then it just had that bios glitch. But if the laptop goes out like the dinosaurs I already have the whole thing backed up to my Synology.

Thready · Nov 9, 2025

Spunk said:
What is the Make and Model # of the laptop?
If it was a desktop the CMOS battery would be CR 2032 coin looking watch battery available in any drug store or store that sells electronics.
But depending on the Manufacturer, the CMOS Battery on a laptop can be a coin size batter that has a wire on it that has to be plugged into the motherboard.
As stated, many new laptops have the CMOS battery soldered onto the motherboard and are not replaceable.

I don't have the model number but it was a $300 ASUS laptop to replace his previous laptop that he dropped out of his wheelchair. I probably will just open it to see if the battery is replaceable and if it isn't then we're already saving up for a new laptop anyway.

DarkShadowMD · Nov 9, 2025

Ejem... just for the record, modern systems are so thin they lack a CMOS battery. I know this first hand because my HP resets settings and gives a bad checksum every time I open it to replace thermal paste, or for example, to upgrade RAM like I did last time. Apparently manufacturers rely on the main battery to hold the BIOS settings and save them settings.

If this laptop is recent build, the most probability is that it will come without a CMOS battery, and the moment the main battery died, everything in BIOS was reset because there was no charge to keep them. Just reconfigure settings or reset to default as soon as your battery has charge and keep going, it shouldn't have any problem. Nowadays batteries have a protection for when you have them to the AC all the time, preventing 100% charges to preserve battery endurance.

Had to press any key to reset CMOS when dad's laptop died.

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