The battery in question is a 12 volt, 31 ah wheelchair batter, though I'm using it in a remote controlled golf caddy. Recently replaced the battery. the old one was starting to just make it through 9 holes and was around seven years old.

Took the new one home last Saturday and put it on the charger and charger showed all the correct lights to indicate charging/charged. Monday a.m. took it off the charger because I was playing after work. When I get it all loaded up and hit the "go" button, it was very sluggish. I had to give it some assistance, particularly up hills. Finished the 9 holes, took it home, back on the charger. Tuesday afternoon I took it off the charger and tested it with multimeter - 12+ volts. Ran it around the yard unloaded, then loaded (very sluggish) for 5-10 minutes and checked it again and it showed 10.X volts. Today (Wednesday) I took it off the charger before work to simulate a golf day and tested it when I got home - 12.9 volts. Ran it some more unloaded (again sluggish) - maybe 5-6 minutes - then tested it again and it was 12.5 volts.

Does the power come from the volts? That's my assumption. Can it test to 12 volts but still not be "full strength"? Leaving the battery off a charger while at work had never been an issue, including with the recent old battery - it started off strong but ran "out of gas" toward the end of the round - so that shouldn't be the issue.

Is there anything I can do to further test things (with the caveat that I'm not particularly electronically inclined)?

I am in contact with the maker of the caddy (Kangaroo Golf), but I was hoping to eliminate the battery as a problem, if possible.

Thanks.