On Sun, 24 Jun 2018 07:30:21 -0400, Paul wrote:

Store the battery at 60-70% charge. Storing the battery at an
even lower capacity would be better, but there is also a danger
it could self-discharge so low, that the charger would never
charge it again. If you left it at 70%, you could come back
three months later and check how much is left. And restore
it to the correct condition again.
snip

Agreed.

Some laptops actually have a control to set the
charging policy. Mine doesn't have that, and my
laptop always tries to charge to 100%. But some
laptops allow avoiding the "saturation charge" portion
of the charge curve, and they stop at around 80% charge.
That was a charging option specifically invented to
enhance battery lifetimes.

My Dell Inspiron has a "Dell Extended Battery Life" power profile that
keeps the battery between 60-70% about 95% of the time. Every so often
it allows the charge to dip to 50% or rise to 100%, but it mostly just
goes back and forth between 60% and 70%. The laptop is over 5 years old
and the original battery still gives me over 2 hours runtime, which is
all I ever asked of it even when it was new.

To the OP: What kind of laptop has a battery that is not easily
replaceable? Tablets and phones, but now laptops, too?