MAKE pal Dino Segovis brings us this handy tutorial on running a stepper motor in “reverse,” i.e. turning the shaft mechanically in order to generate electrical power, instead of the normal usage. He writes:

Any electric motor will also output a voltage when it’s freely spinning. Stepper motors are much better at this because they have many times more poles to pass next to each other thus generating electrical pulses.

The AC current can be used as-is, he reports, to run LEDs, or easily rectified to give DC. [Thanks, Dino!]

## 6 thoughts on “How-To: Use a Stepper Motor as a DC Generator”

1. instead of a stepper motor, will this work?

would this work?
I found a DC magnetic motor. Will this work? It looks like a motor used in electric cars or vehicles. The power rating caught my eye. Could it be that simple? I’m not worried about the RPM, I have that problem solved so I can get any RPM needed without wind power. Could this motor put out as it states 11.5 KW continuous? If so, Why would I buy a 10kw windmill or solar system for \$30,000.00 USD when I can use a permanent magnet DC motor like this for 600.00 capable of 11.5 KW continuous. The equations V(V) × I(A) = P(W). Is this motor really going to put out 11KW of electricity or am I missing something here? Geez, I’d be ecstatic if it would even do 5KW. Sorry for the stupid question. I’m sure you are probably laughing at my craziness.

Power: 11.5 kW cont– 23 kW pk <—– ?
Voltage: 12-72 Volt rated
Max Speed: 3700 rpm @ 72V unloaded
———————————
EMC-RT200 w/
Alltrax AXE7245 Controller
38HP pk. Electric Drive Kit

Includes

EMC-RT200 Motor
Alltrax AXE7245 Controller
Choice of Throttle
Contactor
Wire Kit
Fuse Holder w/ Fuse

EMC-RT200 Motor

The EMC-RT200 is a brush-type, permanent magnet DC motor with very high efficiency. Capable of 11.5 KW continuous and 23 KW for 1 minute. For voltages from 12 to 72 VDC input and 200 amps continuous (400 amps for 1 minute). Designed for battery operated equipment. For more information, see the Performance Information section. Motor weight of 39 pounds. This motor has similar performance to the Lynch, Lemco, and AGNI motors

Power: 11.5 kW cont– 23 kW pk
Voltage: 12-72 Volt rated
Max Speed: 3700 rpm @ 72V unloaded
Size: 8" OD, 7.4 " long (w/o shaft)
Shaft: 7/8"x 1-3/4", 3/16" key
Weight: 39 lbs.

Click on an image above to enlarge in a new window ^
Controller

Alltrax AXE7245 72V 450A Programmable Controller

Alltrax controllers are fully programmable speed controllers for permanent magnet and series motors. The free Windows compatible programming software allows for complete control of max current, max speed, hi and lo voltage cut off, acceleration and deceleration rates and custom throttle settings.

Programmable via RS232 comm port using PC or Laptop
Integrated anodized heat-sink with multi bolt pattern for flexibility
Fully encapsulated epoxy fill – environmentally rugged design
Advanced MOSFET power transistor design for excellent efficiency and power transfer
1/2 Speed reverse option and "Plug Brake" options available

450 Amps
24-72 Volts
Works with 0-1k, 0-5k, k5-0 ohms, 6-10.5V & ITS Throttles

Throttle

Choose from…
– Magura Twist-Grip Potentiometer Throttle
– EZ-GO Pot Box Throttle (PB-6 Drop-in Replacement)

Contactor

Please specify your contactor coil voltage at checkout. 24V, 36/48V, or 72V