# What are the characteristics of a motor that will generate current and is powered by a 30 cc, 2-stroke small engine?

Problem: I am trying to hobby-build a generator using a (old, working, throw-away gas, yard blower) 30 cc, 2-stroke engine. The 2-stroke engine will spin a motor and I want the motor to generate DC current.

My research:

• Normal small-fan motor without magnets will NOT work; and if it does, it is extremely inefficient
• Ideally, one should use a brushed, DC motor to generate the power
• A DC motor used as a generator typically has permanent magnets
• Brushed DC motor is preferred to brushless DC motor (not sure why)
• Brushed motors may be spun/rotated in either direction (CW, CCW); however, one direction (CW) is preferred and slightly more efficient
• One can generate AC current from a DC source using an inverter/converter
• Ideal building blocks: (input) gas/oil mix --> run 2-stroke-engine --> spin brushed DC motor --> generate DC power --> charge a 12 volts car battery (12-volt 1ah; 12 DCV) --> 12 VDC to 120 VAC Inverter/Converter --> 120 AC current (output)

What I have tried:

• I used a small-fan 120-volt AC motor (without a permanent magnet) and realized that it will not work; it generates very little power
• I did google-searches and found some small cheap brushed DC motors on Amazon [e.g. 12/24V 30W High Speed CW/CCW Permanent Magnet DC Motor For DIY Generator (DC 12V 3000RPM)]. Interestingly, its comments/description on Amazon says “The stator windings of the motor are copper wire…” this confused me since I believed that in a DC motor with permanent magnets, the stator is the permanent magnets; i.e. it is not based on stator windings. Also, the motor’s physical dimensions are 1.97 x 1.18 x 1.97 inches. It seems rather small (physically). Is this unit good enough? Will it overheat?
• Try a car alternator - controlling the field current controls the output & therefore the load. May 18, 2020 at 16:18
• Thanks Mike. I had thought about it initially since an alternator would convert and directly produce AC power; however, I decided to first check other alternatives as an alternator is a bit costly (minimum ~\$60 for used item). I will keep it in mind as I would not (then) need an inverter or battery. Thanks for your suggestion. May 18, 2020 at 18:08