To use an automotive alternator to generate electricity, you need the following things:

Alternator without internal voltage regulator
(rebuilt pre 1972 Chevrolet is good)

50 watt, 50 ohm rheostat (try Newark electronics in Chicago, IL for new), Herbach and Rademan (phone 800-848-8001) for used 100 ohm, 25 watt rheostat

Brackets (homemade as shown in photos)

12 gauge wire (black and red)

Ammeter (approx 0-15 amps)

Voltmeter (approx 0-25 volts)


Fuseholder w/ 10 amp fuse

Battery cables (red and black)

Starter cable

Ignition (battery) cutoff switch (from auto parts store)

Misc. connectors and wiring blocks

Car or lawn tractor battery

12v Light or other 12v device to draw power

Fan Belt

Turnbuckle and other misc. hardware

Hook everything up as shown. Note that where red wires cross black in diagram, there is a small half circle (this implies NO connection).

Test the rheostat with a multimeter before using to make sure that as you turn the knob, resistance goes up.

Hook the alternator to the power source with a fan belt (5 HP gas motor, 1 hp+ steam engine, windmill, water wheel, donkey powered treadmill, etc.) and turn on the ignition switch. NOTE: Never rotate the alternator pulley at high speeds without having it hooked up and turned on to the battery, it will be damaged!

Use the turnbuckle on the alternator bracket to get the proper amount on tension on the belt.

Start your power source carefully.

Watch the meters and use the rheostat to contol the amount of electricity fed to the "F" (field) terminal on the alternator. More rheostat resistance=less power output from alternator.

Try to keep the volts at 12-15. Watch your meters constantly! This is not a self-regulating system! The voltage will vary according to speed, and current draw.

If you aren't paying attention, you could damage the system by letting it go over 15 volts. Shut the mechanical power source (5 HP gas motor, 1 hp+ steam engine, windmill, water wheel, donkey powered treadmill, etc.) down if this happens. DO NOT turn off the alternator ignition cutoff switch before stopping the rotation of the alternator that is hooked to your mechanical power source.

DO NOT hook up expensive electronic equipment to this system while it is generating. While generating, use this only for SUPERVISED charging of the battery or such purposes such as lighting.

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