Picked up a 2005 GEM eL from government auction. Batteries are 2023 AGM, seem to accept a full charge. I attached a volt meter to the positive/negative terminals to the controller box. When I turn on the power I have typically 80 volts. I have run for about 30 minutes, stop and go. Seemed to be working fine for a couple of days. Voltage would drop to about 74 volts. Then the next day ran for about 15 minutes, and machine slowed down and stopped. Voltage was down to about 62 volts. However if I turned it off and back on it showed 74 volts but then dropped back down to 62 volts. Could this be a battery issue or maybe pedal/controller.
For some reason I am not seeing where you are plugging in this car between use. (like every day)
If not- you should be. Lead Acid cells(AGM) do not like to sit after drained. They work best if charged up and resting at a high State of Charge.
The general rule is that a 12v battery should not be drained below 50% SOC. Looking at this chart shows 50% is about 12v.
Yes. a 12v battery is considered depleted and in need of charge when it is showing you 12v.
You need to give a good checkup to all of your batteries. There is a chance one or more of them is going dead.
What about warning lights, turtle, wrench, codes etc? Run a wrench over all the battery connections, a single loose one can act like that. How many miles vs. battery condition if you’ve got bars indicating level of charge? It is conceivable that you may only get a dozen or so miles from a charge. I got 16 before swapping to Lithiums. More data please.