Battery problem?

[rbgarst]

I have a 48v club car ds. The batteries are about 5 1/2 years old. When fully charged they each show around 9.2 or 9.3 volts. Bank shows around 56.4 volts. This morning after about 25 minutes of continued driving my state of charge meter had dropped 3 bars and it is really slow going uphill, I mean creeping. I checked the voltage on each battery after my ride and each one showed 8.3 or 8.4 volts and bank showed 50.1. So I assume my SOC meter is not working properly. My question is, why is it creeping uphill if it still has 50volt charge? Do I have a problem other job than the batteries?