Hey I just replaced the accelerator and pedal on my gem that I just bought. It now will run but it goes great for about 1/4 mile then drops all bars to red on battery and slows to a stop. When I bought it it had one marine battery and the rest were gel. I got a new gel battery for that one. Sometimes I turn the switch on and 24 appears after turning lights on it goes back to zero and works the batteries drop.
Short answer, the rest of your batteries need to be replaced. They were abused or tired out by the previous owner. A big clue is that someone dropped in a mismatched battery just to sell the car.
However, depending on the age of the remaining cells(fairly new?), you might be able to resurrect some life out of this pack by load testing each cell and look for another dead one. You might get lucky if some of the others are still holding up. It is not the best solution, but it might get you some more time to sort out this car.
Let the charger go through another charge cycle and unplug the car.
Put a meter on each battery and note the voltage. Write these numbers down. They should all be fairly close to each other.
Then put the meter on the first battery again.
With a firm foot on the brake, press down on the accelerator a bit and see how far and fast the voltage drops. Repeat this for each battery in the chain. A bad battery will be obvious. Especially since you have a new battery in the chain to compare the others to.
Code 24 issus is interesting. It is listed as - Motor current High in FWD. Electrical Fault. Inspect controller.
I’ll have to let the collective wisdom of the board get back to you on this one.
I wouldn’t think it has anything to do with your headlights. I suppose you could try checking your main plug on your controller, blowing it out with air, maybe give it a shot with contact cleaner/wd40 and refasten it nice and tight.