The Steamtug Blog

I have been experimenting with my little Stuart Turner 5A steam engine. Just using my garage air compressor which has trouble keeping up, but I have made a few runs driving a generator I bought. This is all for the intention of running this little steam engine on my boat Edelweiss, to provide electrical power to the beer fridge!

I needed a generator that would not need too many RPM’s as I wanted to direct drive this straight off the crankshaft, like the real generator sets on the ships I have worked on. So I was looking for something that would give me 10 amps, 13 volts at 200 rpm.

So I bought a great little 400 watt permanent magnet, 3 phase alternator. It was rated to reach 12 volts at only 60 rpm but using a clever planetary gear in the front that gave the rotor a 6 : 1 kick up in speed. It made 12 volts on my work bench turning the nut on the drive shaft with my spanner (that’s a wrench for y’all US folk)!

But with 3 phases working together (rectified to DC, of course) the torque required to turn was enormous, and the little steam engine struggled to turn it over, even when I dropped one phase out it jumped around but still found difficulty running over. So I put it onto a bicycle. And here too found it hard to push over the end of the stroke for my legs.

So I bought another little compact single phase high speed job. It is also permanent magnet, for a Kubota garden tractor and supposed to make 20 amps. It needed to spin faster, so I borrowed the power steering belt off Ethyl (my car) and drove it off the 8″ flywheel with some success. I got 13 volts into an 8 amp load.

Next I took off the gearbox on the other generator, made a coupling with an old spanned socket packed with cloth and stiff wire to fill in the drive faces. Direct drive without the gearbox, and 2 phase didn’t reach enough voltage. But with 3 phases, I got up to 9 volts into 8 amps, and 16 volts with a 4 amp load.

Experiments continue, but it seems you can’t beat good old RPM’s to make power!