Non Car Related Question

are these deep cycle batteries, or regular auto batteries? Are you regularly running them low and letting the cart sit for days, weeks, before fully (15+ hrs) charging them? Sulfation occurs as any SLA battery is discharging, but recharging it breaks that up. If the sulfation is allowed to sit for an extended time, it hardens, and reduces the performance of the battery. Does your Club Car charger have an automatic desulfation mode? If so, that may be why it isn't kicking off and "hanging up". It may be intentionally attempting to overcharge the battery for 16-24hrs to recondition it.