Like HowStuffWorks on Facebook!

What is a potentiometer in an electric car?

An electric car has a motor that needs a controller and battery pack to run. The controller is connected by heavy cables to the battery pack and the motor. The controller is like a switch that transfers electrical power in pulses from the batteries to the motor. It is also the biggest part under the hood of an electric car. The amount of power to transfer is signaled to the controller by a pair of potentiometers that are attached to the gas pedal. Full power means that the gas pedal is being floored by the driver, and the battery must deliver maximum power through the controller to the motor to maintain the speed.

The gas pedal has a cable that connects to the pair of potentiometers. Electric cars have two potentiometers that deliver the same signal to the controller. This is for safety reasons. The controller checks that the readings from both potentiometers are the same. If they are not showing equal signals, the controller doesn't operate and no power is transferred from the battery to the electric car's motor. This is designed to prevent situations where one potentiometer might be faulty and could potentially send a signal for a full power transfer that isn't necessary. The potentiometers read the setting of the gas pedal as accelerated by the driver, and the transfer of power is pulsed to the motor from the battery through the controller to regulate the speed of the car.