The Steamboating Forum

(not mine)

https://sfbay.craigslist.org/sfc/clt/d/ ... 42390.html

https://youtu.be/YZxkR8NLEW4

I tried that same? Setup on the tug engine and could never spin it fast enough to make it work. I made a smaller pulley for the alternator and I even had a larger flywheel, best I could get was 9-1/2 volts output at the rectifier. It looked the exact same alternator, I even took it to an starter/generator shop, they tested it and it worked perfectly. I simply couldn't spin it fast enough.

Wound up using a small 60v ? brushed DC motor, works perfect.

If that is just a typical automobile alternator you indeed will not get much power from that configuration, you need much a higher rpm to get into the range for automobile alternators to start producing current. I note the video showing the engine running on compressed air doesn't show the electricity generation...

Unless the alternator has been modified. ...

WindBlue Permanent Magnet Alternators start with the frame of a common Delco automobile alternator, but they replace the guts with permanent magnets and different windings so that it works at lower speeds and without requiring a battery.

I recommend taking a look at WindBlue Power's DC-540 Permanent Magnet Alternator. I have used WindBlue PMAs to produce 200-300Watts with the same PM Research Engine and more with some other steam engines.

Unfortunately WindBlue seems to have kicked the bucket...

Looks like Missouri Wind and Solar https://mwands.com/ sells a similar product. Might want to search for 'PMA'

-CB

Automotive alternators work fine, you just need to spin them fast enough - ours produces 20 -30 amps at normal running speed..... we gear it up by about 13:1 from the crank... (2-stage, ,chain then belt)... the following table gives charging current v engine and alternator RPM...from my spreadsheet and alternator specs....
(sorry it does not format well....there are three columns engine RPM, Alternator RPM and Charge Current)
Crank RPM Alternator RPM Alternator Current (A)
50 679 10
103 1398 30
123 1669 34
147 1995 43
253 3434 68
303 4112 74
550 7464 79

There are numerous PMDC (Permanent Magnet Direct Current) motors on ebay, they will function as motors or generators equally well. I prefer to get Pacific Scientific motors, they are high quality, come 12, 24, 36, 90 VDC, with RPM ranges far lower than automotive alternators. My electric boat uses a 24 Volt 3/4 HP PMDC motor that I got on ebay, new, for $40. Running fine on 12 or 24 VDC since 2004. Get a machine rated for continuous duty, nameplates usually have this rating displayed.

On DC motors what matters is V/K rating. That is volts per thousand RPM.

I'd like to know more about that feed water heater. Cute. Wonder if it could be scaled up a bit and whether it's real any better or lower loss than a tube within a tube type. I'd been thinking about maybe 18" long with a 1/2" copper pipe within a 3/4" pipe for my 3 x 4 launch engine.

Also, I have a Stuart #1 about half completed and was thinking about hooking up a small car alternator to it. But the efficiency of engines that small is not that great. I'd rather find a Stuart Sirius and sort of duplicate the Firefly WW2 battery charger. For use with my low powered ham station. Anyone have a Sirius that they want to trade for a #1?

Mike

have you looked at the small alternators used with a small domestic windmill, max 600 RPM about 300W?
Jack

Thats another consideration too on our boats, the output capacity of the generating device and available horsepower. It requires about 1 hp per 30 amps. Most of our steam plants are maxed out pushing the hull at speed, so to use a 60 Amp generating device on a low battery would be a considerable negative to shaft horsepower.

The setup I have puts out about 10 amps at cruise speed, and there is a noticeable slight loss in speed. 60 amps would be very evident.

I've been out for five days and engaging the generator for an hour er so per day keeps the battery up enough to run pumps, charge cell phones and conservative use of the spotlight. There are inexpensive solid state regulators that I plan to add in the future.

From Lopez Mike: "I'd like to know more about that feed water heater. "

This is a brazed plate type heat exchanger, somewhat "overkill" to heat the feedwater for our typical steamboat feedwater flow. My tube-in-tube heater is only about 0.4 square feet heat transfer surface area, and brings the feedwater to my boiler, about 80 PPH (pounds per hour) at about 194F with atmospheric engine exhaust (212F). Full description of this heater posted on thread "Margaret S Sidewheeler Recent Modifications" in "Members' Websites and Boats"

The plate type heat exchangers have been used as full exhaust condensers in steamboats, almost 10x the heat transfer duty of the feedwater heater, and I believe Radow uses this setup. I prefer shell and tube type condensers, as it is easier to clean out fouling on the seawater side, with flow inside the tubes.