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CMOS battery-how long its life?

Posted: Wed Jan 22, 2020 10:21 pm
by Nasikh
I have been using my X220 since 2011 (9 years), at least 95% of the time in an Ultrabase 3 (i.e., on AC) with the battery in the machine. To this day, I have never seen any sign that the CMOS battery is not working. How long can I expect it to last, given that almost all the time I am working on AC? Should I put in a new one, preemptively, before the original one dies?

Re: CMOS battery-how long its life?

Posted: Thu Jan 23, 2020 4:16 am
by RealBlackStuff
The usual CMOS life expectancy is about 5 years, but can be a lot longer.
As long as the voltage is between ~2.95V and ~3.3V, you're good to go.
If/when you replace it, check that there is no password set in BIOS (or that you know it)!

Re: CMOS battery-how long its life?

Posted: Thu Jan 23, 2020 10:28 am
by MikalE
As far as I know the battery in my T520 has never been replaced either and it's still ticking along. That goes for my two T510's and T500 too.

Re: CMOS battery-how long its life?

Posted: Thu Jan 23, 2020 1:07 pm
by w0qj
The CMOS battery in our T410 is ticking alive and well ;)

From our empirical observations, it is when you fully discharge your main battery, and then let your computer sit there unused (and unplugged) for months at a time.
ie: computer uses the CMOS battery to maintain itself.
That's when your CMOS battery is in danger. Just our two cents.

Re: CMOS battery-how long its life?

Posted: Thu Jan 23, 2020 3:23 pm
by kfzhu1229
The CMOS battery of my T42 and T43/p's all died about 1-2 years ago. So about 12-13 years in my usage.