[GTALUG] war story: CMOS battery AKA Real Time Clock (RTC) battery in a notebook

[Don Tai]

That is such terrible design. They could have put the CMOS battery
anywhere, like somewhere serviceable.

On Wed, 19 Oct 2022 at 19:58, D. Hugh Redelmeier via talk <talk at gtalug.org>
wrote:

> Almost all PCs have settings that they want to keep while the computer is
> off or even unplugged.  Ones that they don't want to keep on disk.  Things
> you set up from the firmware setup screen.
>
> Furthermore, they have a realtime clock that runs when the machine is
> turned off or unplugged.
>
> These are all powered by a lithium coin cell.
>
> Eventually, that battery runs down and you have to replace it.  Five or
> ten years of lifetime seems normal.
>
> When it runs down, the computer will forget the date, time, and all its
> setting when it is turned off.  This is annoying: every time you start up
> you have to fill in the time and other settings.
>
> Luckily, for most computers it is easy to replace: it is in a socket in
> the motherboard.  The battery can be sourced from Dollarama or Amazon for
> a buck or two.  Just get the size right.
>
> For (some? all?) notebooks the coin cell battery isn't used if there is a
> charge in the main battery.  So you may not notice that the coin cell
> battery is failing.
>
> I flattened my notebook's main battery somehow (left it sleeping for a
> week?).  When I powered it on, it had no idea of the time nor what to
> boot.
>
> Upon investigation, I find that I have to completely disassemble my
> computer to replace the battery!  They placed it on the top of the main
> board whereas access is to the bottom.  If you care, you can read page 50
> of
> <https://dl.dell.com/topicspdf/xps-15-9560-laptop_setup-guide_en-us.pdf>
>
> It looks as if I will need some new thermal grease since I have to remove
> the heat sink from the processor.  And the coin cell assembly is not
> generic -- no Dollarama battery.
> <
> https://www.amazon.ca/LeFix-Replacement-Battery-Connector-Precision/dp/B082G35D4R/
> >
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