Homemade mini gasoline generator 12 V from a trimmer

This is the smallest generator that can be made from a trimmer (mower) engine. Extremely small dimensions are achieved through the use of a permanent magnet generator without field windings.
This installation can supply consumers with a voltage of 12 V, and can be used to charge batteries in places where there is no electricity. This is especially true in winter.

Will need

• Engine from trimmer. The lowest power one is perfect (0.6 kW).
  
• In this example, a 12-volt Yamaha motorcycle generator is used.
  
• Bearing from the rod of a lawn mower.

A few words about the Yamaha generator. It was removed from a motorcycle, but it would be fine from any other company, that’s not the point. Its power is about 100 W. The output voltage is regulated by a PWM regulator - removed from the same motorcycle. It receives three-phase alternating voltage from the windings. The regulator straightens and stabilizes it.

To increase the torque speed, the design of the generator differs from classical models in that the rotor rotates outside, and the stator with windings is located inside.

Making a gasoline generator from a trimmer engine

We cut the rod shaft with a grinder. We sharpen and cut threads for the rotor on a lathe. To secure the stator, we machine a sleeve from a hollow aluminum billet.

We press a steel ring onto it, previously turned on the same machine.

We sharpen the hole for the bearing, which is taken from the already unnecessary trimmer rod. We install the bearing, fasten the bushing to the standard mount instead of the rod. We drill holes on the steel ring to mount the stator.
Screw the stator. We install the rotor on the shaft and secure it with a nut.
The frame of the gasoline generator is made of thin aluminum profile. Everything bends perfectly. The engine mounting lugs are also made of aluminum and welded to the frame.

The end result is this design.

Very lightweight design. All that remains is to make a casing for the generator to prevent touching the rotating part.

Examination. Trying to charge a car battery. Charging has begun, as can be seen from the increase in voltmeter readings.

Holds a charge current of 5.5 Amps very well.

It was decided to add an AC outlet to take AC voltage directly from the windings, and there it reaches 80-90 Volts at maximum engine speed. You never know what it will be needed for.

I also introduced a three-position switch into the circuit: middle - off, left - alternating current to the outlet, right - constant voltage 12 V.

An incredibly useful thing in the household, I think it can be useful for many things.
A motorcycle generator is certainly small, but it does not require an initial voltage to start, compared to a car generator. And the weight of the installation is almost negligible.

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