OK to replace CMOS battery safely?

Jedipadawan

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Aug 16, 2016
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OK… Work on wooden laptop proceeds. The base has been - though is being modified, and the screen covering. Yet to fix the screen mounting to the base or to build the keyboard casing.

Given the old U135dx which this will be based on is in pieces I figured I may as well replace the CMOS battery while I here.

Only… While I have replaced the desktop circular CMOS batteries in days gone by without trouble I little more nervous when it comes to a laptop. The u135dx CMOS battery is on a lead with cable and should just plug and go but…

I have destroyed an old 386 by the wire slipping from the solder and wrecking the CMOS. There was no failsafe on those old machine. You lost the CMOS - you wrecked the motherboard.

So, while failure probability is low, the risk is high. If I *somehow* managed to plug the CMOS battery in incorrectly or the replacement is a dud… am I going to damage the motherboard? Do today's motherboards have any kind of BIOS protection? I have never replaced the CMOS battery of a laptop before!

I want to extend the life of this machine by at least another 5 years… not kill it in an instant.

Any advice gratefully received.

And, while at it… you might want to take a look at my hardware hints and tips including how to build a fully functioning, warp capable starship!

https://forums.linuxmint.com/viewtopic.php?f=58&t=229112
 

nukemaster

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I do not think you will have issues with no power while swapping the battery. Worst case the notebook forgets the time and some settings and you have to enter the bios and change some settings back.

I am not sure about laptops, but many desktops use the standby power(laptop would use its battery) to keep settings. The leaves very little load on the cmos battery.

My old laptop has never required a new battery and it is a bit over 12 years old.
 

nukemaster

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Replacing the battery should not be an issue.

Just make sure you get one with the same specs(voltage being the one you are after in this case. many are 3 volt lithium 2032 style batteries) and do not reverse the polarity(do not flip + and - on the battery).
 

Jedipadawan

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Aug 16, 2016
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Hi Nukemaster...

I will be getting the exact same model specified by laptop model.
Yes, i will be very carefully re: polarity. As it is the plug is polarised so it's not really an issue

But... if somehow the plug does not connect properly s thee is no a charge... just in case, against all the odds, will the laptop be OK.

That is my question. Just being paranoid here. It's just a plug in CMOS battery but, having killed one laptop in my lifetime, I'm just triple checking.

Many thanks!
 

JacobVR

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Jan 14, 2016
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Actually, I found out that in Laptops you Really never will have to replace the battery, as I noticed one time when I had to remove the CMOS Battery that the laptop uses it’s Battery Pack for thismatter also, I do not know if this is a standard for all laptops but my Acer Does uses it’s own battery instead of a CMOS CR2032 battery
 

Jedipadawan

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Aug 16, 2016
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Interesting. Only I will be replacing the CMOS battery while the laptop is in total pieces and not connected to a battery. It's the only way to access the CMOS battery. Also, although the battery is still gong strong, it is five years old and will need to be replaced at some point. Indeed, my father in law had no registered that I needed to access the battery pack and had to explain to him carefully that I had to be able to access the electronics and juts have a sealed box. He has added hinges!

So I am still a bit nervous. It will be switching out the CMS battery with no power! Fro my reading it seems modern laptops have a failsafe and replacing the battery will not cause harm even if there is a misfit. But having killed one old laptop before, I am still nervous.

Can anyone confirm?
 

nukemaster

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Moderator
I do not think you will have issues with no power while swapping the battery. Worst case the notebook forgets the time and some settings and you have to enter the bios and change some settings back.

I am not sure about laptops, but many desktops use the standby power(laptop would use its battery) to keep settings. The leaves very little load on the cmos battery.

My old laptop has never required a new battery and it is a bit over 12 years old.
 

Jedipadawan

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Aug 16, 2016
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>"My old laptop has never required a new battery and it is a bit over 12 years old. "

That's probably the money quote! It's just that, once this machine is put back together it ain't comingapart easilly. But the battery will be removable and that sounds like the key.

Thanks to all!
 
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