The engine of a solar car I am designing(for my fictional stories but I would like a scientific point of view on this) is literally a DC circuit combined with mechanical force. First of all, there is a rechargeable battery. I would say it is about 24V fully charged. There are 2 wires coming off the battery(Positive or hot and Negative or neutral respectively) Connected very closely to the battery are the positive and negative leads of a voltmeter. This voltmeter is used as a battery gauge. I am not sure at all where to put an ammeter to prove the battery is dead or not. I mean the circuit is complicated as is(multimeter wouldn't work so I do need a separate voltmeter and ammeter for this circuit). There are 2 separate motors, each with their own positive and negative wires. These motors is where mechanical force comes into play. Each motor has to have the same voltage and current if the car is to go straight and the only time it should be different for each motor is when turning the car while it is running(Voltage should be lower in the motor that is in the same direction as the turn(so lower right motor voltage, right turn, lower left motor voltage, left turn). Also each motor is connected mechanically to the wheels in order to make the car move. But the only fuel here is the battery and this battery is a solar battery. The radio, speedometer, and distance meter(don't remember what it is called) also have their own positive and negative wires. All the negative wires are connected to the negative terminal of the battery and all the positive wires are connected to the positive terminal of the battery. The voltmeter has to be turned off separately from everything else. An ammeter would also. But anyway, I am not sure how I could without an integrated circuit(basically a mini computer acting as a resistor in this case) control the voltage in such a way that less current is sent to either the left or right motor(depending on turn direction) and thus there is a lower voltage across that motor when the car is turning. I mean any old resistor won't do. I am not sure if variable resistors will work or not to drop the current and the voltage in 1 and only 1 motor during a turn. I was wondering if you could help me work this out.