I have a gem car that was reconfigured to support marine gel batteries.
After sitting for a while, I charged it up and drove it to town and back. Now it won’t start because the battery is low. I checked all the batteries with a multi-meter and they are all ~12 volts except the battery on the driver’s right hand side – the one connected to the power switch – has dropped to ~5 volts.
I put it on a trickle charger but after a day it is still at ~5 volts.
In addition, I think this particular battery is a replacement from a previous individual battery that went bad, probably located in the same spot.
What do you think is going on here?