[BizarroLand]

Lithium batteries have an approximate 10 year shelf life under optimal conditions. Possibly less when heated consistently by a laptop running 24/7.

If your laptop is already 6-8 years old then if you want to keep the battery in as a UPS system it may be worth considering purchasing a new replacement battery and installing that (if it has not already been replaced)

Most computers will only need a small screwdriver and 10 minutes of work to swap the battery, although you will want to check youtube/ifixit for your specific model first just to make sure the battery isn't glued in or otherwise difficult to remove and replace.