The battery in one of the road runners is at least 12 years old (red top optima that was in the car when I got it) and is still good...it's on the battery tender whenever the car is in the garage. The battery in the Indy Ram is about 10 years old, also on a battery tender.
I am two years in on the third battery in 25 years of road time...
The first two went 10+ years...
Neither were ever on a 'tender'...
There is for sure a sweet spot of usage for batteries. The ones that last 8-12 years are usually not used often, but kept clean and used "just enough" to stretch the life span. However a lot of the batteries that last so long are bad as far as CCA to spec goes but they still have enough CCA to start the vehicle. Often car guys want the most CCA they can possible get not realizing that the 440 six pack roadrunner only needs like 400CCA to start, so that 800CCA battery can still start it for years after it would fail a load test.
My dads 08 ram was having no problems starting recently, it had 7 year old batteries in it. The truck still started fine but both batteries tested bad at the rated CCA. Both batteries together were good for about 750 CCA instead of 1700.
