A little off-topic, but worth saying.

The best way to get the longest life from a lead-acid battery is to
always keep it topped off. It's amazing to me how many people use
their batteries, then let them set in various states of discharge,
then charge it the night before they go flying again. Or they don't
charge it at all until their instruments quit. Some might not know
there are chemical differences in a battery at different states of
charge. The more you keep it topped off, the longer it will continue
to perform well.

I have two 7ah batteries that I alternate. The first thing I do when I
get home from flying is put it back on the charger. Five years old and
going strong. I test them once a year with my West Mountian Radio
battery analyzer. They're almost as healthy as when they were brand
new.