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

[Dave Collier-Brown]

As Honda once said in an owner's manual, "engine does not contain any service parts".

I think you were supposed to throw the bike away when the oil got dirty (;-)

--dave

On 10/19/22 21:10, Don Tai via talk wrote:
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<mailto: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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--
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
dave.collier-brown at indexexchange.com<mailto:dave.collier-brown at indexexchange.com> |              -- Mark Twain


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