Bought my 172N 10 years ago: had a new Gill 24V lead/acid battery in
it. Three years later, cranking speed diminished slightly, so in goes a
new one. Three years later, another one. Hmmmm. Batteries must last
about three years. Arguing with success, I got one of them thar RG
Concordes from Aircraft Spruce when the last Gill slowed down. After a
little less than a year, cranking speed diminished slightly. Then
stopped altogether. Cowl off and on for charger hook-up several (too
many) times. PITA Called Aircraft Spruce. No problem; just send
documentation that came with battery (o.k.) and copy of log books. Huh?
I didn't have to send copies of the logbooks when I gave my credit card
number to buy the battery. Logbook copying, besides being none of their
business, is onerous, time consuming, and burdensome. So fukit; called
Sky Ranch for another Gill. Life back to normal.
I guess I'm just gettin' old and cranky. Flame away if I'm too far
beyond left field.

Blue Skies
N5217D based HTH