Running an alternator in reverse?

Jack Shaft City

D.Duck44 said:

If rpm becomes a problem, it would be simple enough to set up a jackshaft and then you could gear up twice.

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Yes, Since the engine does not turn fast enough, I will use a jack shaft to get the RPM up high enough. The engine RPM is 245 and this is already stepped up to turn the propeller at 333 RPM. I plan to drive the alternator off the propeller shaft thru a jack shaft (or two).

IF you take the flywheel to a machine shop and have it turned to accept 2 V belts over 100A would be available with an OTS alt.

You could use a small Honda generator as back up for extended trips

FF said:

IF you take the flywheel to a machine shop and have it turned to accept 2 V belts over 100A would be available with an OTS alt.

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That would work if there was enough 'meat' on the flywheel. The flywheel rim is 3 inches wide but only 3/8 inches thick. Since the prop shaft is already turning faster I'll just drive it from there.

bayview said:

You could use a small Honda generator as back up for extended trips

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Yup. That's an option I have looked at. I may do that if nothing else pans out. The downside is having to carry two different types of fuel, gas and diesel. It looks to me that the John Deere PM alternator is going to work out.

Excuse me for not reading through everything, but what is your 12v amp draw for steady state running? I think you posted 15A back somewhere?

Also, with a 10" flywheel you do not need to cut v-grooves in it. It will have plenty of contact length/area with the v-belt just running flat on it to do what you need. The alt v-pulley will guide it just fine.

Ski in NC said:

Excuse me for not reading through everything, but what is your 12v amp draw for steady state running? I think you posted 15A back somewhere?

Also, with a 10" flywheel you do not need to cut v-grooves in it. It will have plenty of contact length/area with the v-belt just running flat on it to do what you need. The alt v-pulley will guide it just fine.

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I cannot put a belt on the flywheel, as when a steam engine "hangs up" on TDC or BDC the operator needs to kick the flywheel to get it moving again. This only happens occasionally but can be serious, like when you're reversing while approaching the dock.



My amp draw? The boiler blower (it's a "Beckett" furnace blower) has a 80% on, 20% off duty cycle. When it starts there's a 15A "peak" then it settles down to running at a few amps. Haven't measured it. But the important part is, is if the battery amperage available is less than 11A the control circuit will refuse to light off. What I've learned to do is steam away on one battery until it quits, then switch to the other battery and steam home. Kinda limits my range donchya see? For the rest of it I have LED nav lights, a Rule bilge pump, an Aquajet pump for the sink, and a PumpTec backup feedwater pump in case the mechanically driven pump fails (all of which are intermittent loads) and I'm running OpenCPN on a laptop that plugs into a cigarette socket, but of course that can run on it's own battery if need be for hours.

Hi Steamguy, Nice photo - that hull looks to be perfect for steam conversion - good lines with the vertical boiler & stack.

Didn't see what type of battery you are using. Some of the newer lithium have a much higher power density than the typical lead acid. Bought a stack of cells from a junk yard - Chevy Volt - still have to charge them.

Good luck - good steaming weather coming!!