A 80% battery is just that an 80% chunk of lead and steel worth about 2 to 3 hours of hard use before it needs recharging. I have sent out batteries out for cleaning , load test and acid adjustments. The battery company took as many a three batteries to make one good one rated at 80%. They also informed me as to the limitations of a 80% battery. I ended up having to pretty much replace all the batteries where I was the maint mananger. Replaced with DEKA batteries. Paid a little more but got it back in longer service.