Last spring I installed an autotransformer so I could take 240VAC off my inverter, and I've learned that my well pump and my welder (the only things that need 240VAC around here) run much better off the inverter than they do off the generator. So we decided to build an alternator for the listeroid that's dedicated to charging the batteries.
The alternator is basically identical to the ones we build for 10 foot wind turbines. Just like the steam engine project I turned out a wheel hub to fit the shaft of the engine.
The magnet rotors are 12 inches in diameter each, with 12 2 inch dia x 1/2 inch thick N40 grade NdFeB magnets. We banded them with stainless steel and cast vinyl ester around them.
There is the engine with one magnet rotor mounted on the shaft.
We built a 'stator bracket' out of angle iron that bolts to the engine where the fuel tank used to bolt on. The 3-phase stator has 9 coils, wired in star. Each coil has 28 turns of wire - we wound with 4 strands of #15 gage wire.
There it is all finished up!
A view from the side...
It pretty much works as I had expected. 650 rpm (the rated speed for this engine) gets us right at 2KW give or take a bit depending on battery voltage. It gets a bit warm to the touch but certainly not anywhere near 'hot'. It's very efficient. It's also much easier to start the engine now that the belt is gone. I'll leave the old generator on there and keep the belt for 'backup' but as it is now it's much more efficient and a much more practical generator. As it's currently setup we are getting right at 8kWh from a gallon of diesel fuel. Soon we'll add a second tank and experiment with running veggie oil!
Pictured above is the sine wave of a single phase produced by this alternator.
The 'otherpower.com' engine room.....