Super low voltage 2000 e825

Newbie owner here of 2000 e825. Has 6 Trojan maroon batteries not that old per guy I bought from. Used my car a few rides just fine. Charged it my first time after it had been sitting a few weeks. Came back overnight and now nobody’s home at all except dash green elec display showing four 0000’s. No headlights, no e-brake buzzer, No ignition response, etc. Checked batteries w volt meter and they are all super low like 1.7 - 3.2 V ! Could all the batteries got shot in a matter of a few weeks? Can I use 12v external car charger on each battery if they are still all connected/linked together or do I have to disconnect the chain of batteries to charge each truly independent of another?

If your going to leave your gem for more than a could days, you need to turn off the battery disconnect or it will drain your batteries. That would be my guess on what happened. Hurry up and put a manual charger on the batteries to get the voltage up enough for the the gem charger to kick in, do it ASAP having the batteries drained down that low is not good for them. Try to keep them all around the same voltage when manually changing them so they stay balanced.

Important also to check the electrolyte levels, Flooded Lead Acid (FLA) are notorious for drying out and that definitely damages them. Use only distilled water to top off to the “full” indicator in the fill hole.