[throwaw-zxcvbn]

Apple replaces a laptop battery for free under Apple Care if its capacity falls below 80% of design capacity.

(Note that it's measured using Apple's diagnostic tools, not using the value displayed in the System Report).

Assuming, hypothetically, that some selfish person were happy to get a new battery paid by Apple for their expensive laptop as it approaches the end of the AppleCare contract, but the diagnostic pegs it at over 80% - would it be possible to push it under 80% over a few months? How? (Not a question most articles on laptop batteries address, for some reason...)

[skidd0]

I know when I was interested in a similar question several months ago, the advice I found was that laptop batteries like to stay at a higher charge level. Depleting the charge and allowing the cells to remain empty should damage the battery's capacity.

[solarkraft]

Lithium-Ion batteries really dislike being used to their limits, e.g. charging to 100% and discharging to 0%. They also dislike heat. Those should kill your battery fairly quickly.