TV battery life? And Interstate longeivity? Diesel trucks.

I replaced the original 1997 Ford batteries in 2016 before we went on a cross country trip. They were still good but I couldn't believe they would last much longer. The truck is only used to haul the camper and the battery minder is always plugged in when it is parked. I am running the Interstate batteries now and if they last 15 more years they will probably outlive me.