Man says running it at idle for 15~20 minutes once a month is not enough to keep them in top shape.
One died & put all the work onto the other, which decided to go on strike, demanding higher voltage. Fortunately I have access to a heavy duty charger.
Surviving battery is at 90% state of health according to BM’s testing gadget… some good news, at least.
Problem came to light when I did a test-run before taking a prospective buyer for a test-drive. Only just managed to light the fire.
Decided I couldn’t sell her with a problem I know about, so called in the expert, who told me one battery OK but I should book a funeral for the other one.
Pity I can’t add another $200+ to the asking price…
Gotta wear it as part of maintenance. Warranty on heavy vehicle batteries is 12 months.