Can You Run an Alternator in Reverse?

An alternator may not be in the best place in your car.

Moving the location of an alternator in an engine compartment is an easier process than most people would think. Whatever the reason you need to move it, with the right mounting brackets and fan setup, your alternator can be turned upside down and run in reverse.

How the Alternator Works

Because an alternator produces alternating current (AC), which does not have a negative or a positive as direct current does, it does not matter in which direction the alternator turns. AC is omnidirectional, meaning it flows back and forth and moves in either direction. Direct current only flows in one direction.

The Alternator Charges the Battery

The systems in a car operate from direct current (DC) converted from the alternator's alternating current via a diode bridge. While a battery starts the car, when the engine runs, the alternator powers the DC systems as it continually recharges the battery.

Reverse an Alternator's Direction

When you reverse the direction the alternator turns by moving its location, also add a fan that reverses its direction as well, if it currently does not. Because the majority of fans that cool the alternator run in only one direction, if you reverse the alternator without changing the fan to match its direction, the fan will not cool the alternator and the alternator will overheat and fail.

References

• Lextreme: Lexus-Toyota Reverse Alternator Mount
• Mister Fix It: Alternators