How to Use a Car Alternator to Make a Generator

eHow may earn compensation through affiliate links in this story.

Things You'll Need

  • 1/2-inch plywood sheet, 4 feet x 6 feet

  • Car alternator

  • Alternator belt

  • 8 lag bolts, 1/4-inch

  • Power drill

  • Carbide bit, 1/4-inch

  • Horizontal shaft lawnmower engine

  • Power converter, AC/DC

  • 4-inch steel pulley

  • ARC welder (optional)

  • #3 filler bar (optional)

Did you know a car alternator can be turned into a generator with a little know how and persistence? The car alternator's role is to produce electricity for your vehicle. So, with minor modifications, the alternator will produce electricity for a home. It charges batteries and runs small appliances or lights. Once hooked up to a lawn mower motor the generator produces a charge like it is still in your vehicle.


Step 1

Mount alternator to 1/2-inch plywood sheet with 1/4-inch steel lag bolts.

Step 2

Place horizontal shaft lawnmower on top of the same plywood sheet. Arrange the motor so the shaft is parallel to the shaft of the alternator. Mark the sides of the lawnmower motor for mounting with a marker and remove the motor.

Step 3

Weld a four-inch steel pulley to the lawnmower motor shaft using an ARC welder and #3 filler bar. You can have this done professionally if you're not proficient at welding.


Step 4

Place the lawnmower motor onto the plywood base again and fit a car alternator belt around the alternator pulley and the motor shaft pulley. Slide the lawnmower to the side so the belt is tight.

Step 5

Drill holes for mounting the lawnmower motor to the plywood with a 1/4-inch bit. Use 1/4-inch lag bolts to secure the motor to the plywood.

Step 6

Connect an AC/DC power converter to the alternator terminals. Hook up your battery or appliance to the AC/DC power converter.

Step 7

Power on the lawnmower motor to produce electric current.


Adjust the size of the pulley on the lawnmower motor shaft to create the proper speed for producing electricity with your particular combination of alternator and lawnmower engine. Belt size will vary depending on how far apart your alternator and engine shaft are positioned.


references & resources