my Mac guru advised me to *always* run on battery power

I think running on battery all the time causes unnecessary batter cycles and will actually shorten battery life.

You can run off power adapter when available as long as you use the battery on a fairly regular basis.

Regards,

Captfred

My thought is that your "Mac guru" doesn't know what he's talking about.

Apple recommends charging and discharging the battery at least once per month.

A average lifecycle of the new batteries is 1000 full cycles, then it starts dropping to 80% capacity.

1000/12 months = 83 years. Average life of a MacBook Pro is anywhere from 3-7 years.

So likley one can discharge the battery a little more often than once a month. 😝

12 times a month for 7 years of life, 24 times a month for 3.5 years (or once a day apx)

https://www.apple.com/batteries/notebooks.html

Might be time to find a new "Mac Guru". That one doesn't appear to know what he is talking about.

Allan