[Blessed66]

Depends on where you live, to an extent, as well.

Couple of years ago the average life of an automotive battery was reported to be 2-5 years. Cold snaps and hot spells, along with discharging, are the worst enemies of a lead acid battery in normal operating conditions.

Also, I did some fact checking. It appears the majority of Odyssey and Optima batteries are AGM. I swore at some point (this may be more of the above reference "Gel" & "AGM" catchphrasing) they were advertised as Gel batteries? I can't find any old literature or advertising the back that up, so maybe I've just lost my mind.

At any rate, if your battery is NOT a deep cycle, you also need to know that 10.5V is considered 0% charge.