batteries can be funny things.
Last year was driving the old david brown tractor at work at night in the vineyard with lights on and then the next morning it wouldnt start, so jump started it with a fendt. Then ran it for a while to charge it up. next morning same problem, jump start, run it, then put it on charge overnight. Started in the morning fine. next day, dead as anything. Re-charge the bettery...fine. next day dead. jump started it...fine. next day fine...next day fine, back to normal!!!!!