How do Electric Cars Work?

When you press the accelerator pedal in an electric car you are telling the controller how much voltage to provide to the motor from the batteries. In the simplest example the controller would act as an on/off switch. You press the pedal and the full power from the batteries is sent to the motor. To control your speed you would have to continuously press and release the accelerator. This would be rather inconvenient.

Instead of pressing a switch on and off the acellerator turns a potentiometer which in turn tells the controller how much power to send to the motor. The controller then pulses the power on and off at the correct rate to maintain the speed the potentiometer is sending it. Think of the controller like a gate that quickly opens and closes at a rate designed to keep the motor in the speed parameters you desire.

Most cars use a redundant system of two potentiometers, the controller checks to see that both are sending the same signal otherwise it remains off. This prevents a dangerous situation that could occur if a potentiometer failed in the full-on position.

All of the batteries in electric cars must be charged from an external power source. Charging time depnds on the type and capacity of the batteries and the type of outlet they are charging from. A standard 120v outlet can provide about 1.5kw per hour of charge. If you plug it into a 240v circuit then about 6.6kw per hour can be charged, drastically cutting charge time.

Batteries also eventually lose their ability to hld a charge and must be replaced (See our battery life article for more information), when calculating efficiency this must be taken into account.

With so few moving parts, electric cars are much simpler than an internal cobustion engine vehicle. The fewer moving parts also means less maintenece. For more on electric cars, see our article page.

No comments have been provided.