The original CMOS battery in my laptop - a 2032 lithium coin cell -
lasted 5 years. Since then the various replacements seem to last
only 6 to 9 months. The laptop power battery gave up after 18
months and was removed from the laptop perhaps 3 years ago, so I don't
think the relatively short life of the CMOS battery is due to the
absence of the main battery.

I intend to solder an extra CMOS battery in parallel and in an
accessible location, so I don't have to deep strip every time.

I'm guessing the short life is down to brand and, if so, does anyone
have any recommendations for the best make of coin-cell batteries?

Many thanks

Martin