I’ve had batteries last up to 12 years, replaced the 12 year old one in our 72 Monte Carlo because we were going to drive to Ohio for a VCCA tour, it was a delco that was still working ok just tested a little weak. I’ve never used a battery tender, and usually get 4 to 6 years out of the 6 volt batteries I buy at the farm store. 5 of our 9 vehicles are 6 volt plus the tractor.
