I'm not an expert in electric car conversions. I do know that if you are reading a 48 volt system this means you have connected the 12 volt batteries in a series by connecting the positive terminal of one battery to the negative terminal of another battery. If it is supposed to be a 12 volt system connect the batteries in a line by connecting the positive terminal on one battery to the positive terminal to another battery. And negative to negative terminals. So that all batteries are jumping positive to positive and negative to negative. The same way you would jump a dead battery of a regular gas car using another vehicle.
