I'm still not happy with our electric motor. Well, the motor is great, but storing electricity to run it is a pain in the neck. Whoever can engineer a more energy-dense storage method for a reasonable price will surely make a Brazilian dollars, some of them mine.
We bought a power supply box from an electrical supply store, and had it shipped to Sipsey's apartment in the city. This box, about a foot long, 3 inches thick and 5 inches wide, takes 120vac in and makes 48vdc out. Our little suitcase generator makes 1.6 kW, so we get about 30 amps of 48vdc power. There is an adjustment screw on the power supply, to adjust the output voltage.
We ran an exterior grade 12awg extension cord from the 120vac plug on the generator to the power supply. Then from the 48vdc we go to a switch. The switch has inputs from the battery bank and the power supply. The switch outputs to the motor.
Somehow the dealer for this product doesn't include the mounting brackets with the box itself. They are sold separately, cost $.50 each, and were out of stock when I ordered. Argh! So instead of having the perfect parts for $1.00, I bought a stick of aluminum for $12.00 and had to make it myself. Grrr. The stick of aluminum wasn't quite big enough, so I had to use extra nuts as spacers to get the bracket to hit both the wall and the mounting holes in the power supply. They are held on by bits of tape so they'll hold still while we install it.

Heaven forbid, I actually put it together correctly (though I won't show you the final installation until I fix a few cosmetic errors that a real electrician would have a fit over). We fired up the generator, and it made the motor work! Though, of course, I had the voltage up too high (still well within the motor's limits), and overloaded our poor little generator. That was kind of exciting, since we started drifting towards the mooring field. We switched it to battery power, picked up one of the tons of free moorings offered by Port Washington, and troubleshat. I shortly decided the power supply was asking for more power than the generator could create, and the generator stopped making power. So we simply restarted the generator and all was well. I also found out that if I drop the throttle quickly it turns off the power supply, but if I bring it down slowly it's fine.
This is the lowest cost option for long duration motoring on our boat. We have considered many options, and this is probably not the longer term solution, but it is sufficient for right now. Other options have included more batteries, lithium batteries, an outboard, a 2nd generator, a diesel generator, or a new diesel engine. Does anyone have a different option we haven't considered? I"m pretty sure we've got the pros and cons of these options pretty clear.
Moore Better Later