I would consider a Load Tester for the battery. You could start to see "cells" shorting in older batteries. Cold Cranking Amperes (CCA) could give you some idea of battery health. Hey but if you know your limitations with older batteries then I wouldn't take cross country trips. Great video, very informative.
only way to truly know the state of any lead acid battery is with a hydrometer. those batterys are older and with that said there total capacity is less. yes they charge fully and will read full voltage but as soon as they are put under a load there capacity drops much faster then new batteries.
