My original battery got weak after about 3.5 years and I replaced it.
Now you've forced me to look at my replacement, which is leaking from it's top, causing corrosion...something to deal with, shucks, but thanks.
Running a battery down, like leaving the lights on, just one time even, can cause a wimpy battery to not be able to restore itself.
Our best bet would be a deep cycle battery...why didn't I do that ...
My lifetime experience is that battery life varies greatly, from 2 to 6+ years.
Note: In some forums, members have reported having trouble with short life of Optima agm type batteries, since they moved their production facilities to Mexico...yet my research today shows me that move was ten years ago. Johnson Controls owns Optima. All auto batteries that I've seen in recent years are made in Mexico.
"it's probably from the mexican water. there is a reason they say "don't drink the water" when you go down there
maybe the batteries don't like it either."
Recovering an AGM battery which is difficult to recharge: