How Does a Heated Car Seat Work?

A red car on the road

Heated car seats are great additions to any boat, truck, or car and are included on many luxury models. The technology behind heated car seats, however, is no more sophisticated than that in an electric blanket. In fact, a heated blanket is essentially what the manufacturer has turned the car seat into.

The Resistor

Heated car seats work because a heating coil has been placed beneath the seat cover of the vehicle. A heating coil is a long element of wire through which electricity passes. The heating coil is referred to as a resistor because as the electricity is flowing through the coil it is resistant. The resistance causes friction and is released in form of heat.

The Relay

Just like many of the systems within a car, heated seats run on a relay switch. The relay switch is a relatively simple mechanical trigger that allows the device to begin receiving power. Used much like a railway stitch which allows trains to switch tracks, a relay allows electricity to switch circuits from a small amount of power to a much larger source. When the seats are turned on, a small amount of electricity begins flowing into the coil from an initial circuit. This initial circuit does not have much power output and is only used to create enough energy in the coil so that a magnetic field can form. The magnetic field pulls a lever and flips the relay switch for the heated seats to now receive power directly from the battery of the car.

The Thermostat

A silver car.

A thermostat is included within the seat covers as a precaution against overheating If allowed to run, the heating coil within the seats would continue to heat indefinitely. This overheating could cause a fire, injury, or damage to the entire car. As a precaution, the thermostat is set to monitor the heat output. Once the heat reaches the thermostats set temperature, it stops the relay power, the relay switch is opened, and the seats receive less power (or no power) until they cool down. When the seats begin to cool off too much, the initial relay is triggered by the thermostat and the seats are heated by the battery once more.

The thermostat is also what controls the high and low settings within many heated car seats. The buttons on the steering wheel or seat bracket connect to different setting levels for the thermostat. This allows for the thermostat to have several levels at which it turns on or off to control the heat.

Heated Car Seat Covers

If a heated seat does not come with the vehicle, it can be purchased as a heated car seat cover. With an adjustable strap they are designed to fit even strangely shaped seats and still provide comfort to the bottom and lower back of the chair. The largest benefit of upgrading to a heated car seat via a cover is that it doesn't require any invasive installation. Heated car seat covers plug into the standard 12-volt adapter and run identically to those which are mounted directly into the seat.