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Old 22-02-2007, 15:13   #1
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Power-on-Demand Generator

I was thinking of buying a electric start gasoline 115/240 volt generator for the boat.
Are there add on systems which will start the generator "on demand" that is automatically start the generator when the freezer/air conditioner cycles.
I was in a gasoline powered golf cart recently and the motor started and stopped by depressing the accelerator.
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Old 22-02-2007, 15:25   #2
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Yes, there are such systems. But, I would NEVER put one on my boat. I've seen 'em on houseboats, but IMHO this is VERY DANGEROUS. The combination of a gasoline generator with start-on-demand scares me to death.

Bill

Hmmm, let's see, maybe a hot water-on-demand propane water heater for the shower?
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Old 22-02-2007, 15:30   #3
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power on demand generator

It doesn't scare me.
Can anyone tell me what they are called and where I could look at buying one.
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Old 22-02-2007, 15:58   #4
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Hi beau
It seems a lot of people live in fear. Check this out, it might help.
Houseboat Forums: On-demand Generator
good luck and do not be scared.
Paul
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Old 22-02-2007, 16:30   #5
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If you get an autostart gen set, at least get diesel. Seriously, starting a gasoline engine without first ventilating the compartment is asking for explosion and fire.

There are somethings worthy of fear. I don't care what house boats do, wouldn't have one up my rear if I had room for the Queen Mary.

George
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Old 22-02-2007, 16:38   #6
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on demand generator

Thank you for your concern. The gasoline generator is to be placed in a soundproof box , above deck, with a continuously running 12volt fan.
That is, the fan starts 3 minutes before you start the motor. These systems are very popular in Australia and are manufacturered by a number of suppliers. There are sound baffles on each end of the box. They work very well and are very quiet.
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Old 22-02-2007, 17:21   #7
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BlueWater power boats installs this system in all of their boats and I believe some are diesel.
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Old 22-02-2007, 20:32   #8
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Set up properly, it shouldnt matter what fuel it is on. Gasoline is only an issue if the fuel or it's vapour gets into the bilge/engine room, not because the engine runs on it. If the system is designed to have a remote fuel tank, then it doesn't matter where the genset goes.
However, have diesel genset simply means you don't have to have another fuel. The fuel can come from your main tanks.

As for "on demand", not knowing the finer deatils of what you are doing, I would suggest this may not be the way to go. If your AC and feezer and what ever are cycling a lot, then the genset is going to be stop/start an aweful lot which is going to create a lot of wear. I would suggest you use a battery bank powering an inverter that will run the equipment and let that be the regular "on demand" power device with the Genset charging the battery banks when the voltage gets low enough. That aspect can also be made automatic.
If on demand generating is really the way you want to go, then an auto start system could easily be made and retrofitted to the genset.
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Old 23-02-2007, 09:40   #9
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I have started looking into this area, and I would say a 12v system looks interesting (for me anyway, because most of my demand is 12V) A DC generator can vary in speed according to load and quite easily auto-start if needed. So, a DC generator charging a battery bank, with an inverter for the odd 110/240V appliance seems attractive.
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Old 23-02-2007, 10:32   #10
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The inverter type Gensets like Honda, work by having an inverter produce the output and the genset powering the inverter. As the load on the inverter increases, the genset speeds up to produce the required power. So the engine speed alters to the load.
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Old 23-02-2007, 11:47   #11
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Moby, Are you looking into a permanently installed unit or a portable and what units have you considered?
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Old 14-07-2010, 05:49   #12
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Originally Posted by beau View Post
It doesn't scare me.
Can anyone tell me what they are called and where I could look at buying one.
No problem for you to purchase a generator (electric start) diesel or petrol powered with demand-start.

If you contact any Honda Power Equipment Dealer in Australia you may obtain details on generators with this feature.

Or contact Honda MPE (Australia) direct telephone 03 9290 1133 email powerequip@hondampe.com.au
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Old 14-07-2010, 08:21   #13
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Greetings and welcome aboard the CF, Deejays.

It might be interesting to learn what Beau did, following his 2007 query.
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Old 14-07-2010, 09:56   #14
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Why anyone would want to do this on a boat, I can't understand. Auto-starting a genset just because your refrigerator compressor cycles on?! Imagine the wear, tear, noise, and expense from having a genset cycle on and off all day and night to respond to every little fluctuation in demand.

What, are you not going to have a battery bank? Battery banks manage fluctuations in demand with vastly greater efficiency. You can capture power from your main engine when you're motoring also, so you don't have to generate. You can take with you power stored from your shore power connection, too.

The coventional setup of battery bank charged by main engine/shore power/diesel genset/(and solar and/or wind if you like) is not conventional because the whole world of cruisers are stupid. It is the most efficient and convenient way to power your boat using currently practical technology.

It is best to equip your boat with 12v, or better 24v equipment including refrigeration, but for those things which are not really practical to run on DC you can use an inverter. But air conditioning demands a lot of power, and to air condition anything other than a tiny space with a huge battery bank will need a generator running pretty much continuously.

I suppose there might be some sense in a generator auto-startup system for the specific purpose of running air conditioning -- the only electrical consumer I can think of that would benefit from such an approach. You could achieve a benefit in having the genset shut down when the A/C compressors are not needed. Auto-start systems exist for diesel generators (at least) -- they are used for standby power applications on land. I don't see any technical obstacle to doing it -- you could design such a system to supply a certain amount of power to the A/C system -- enough so that the brain is active and understands when the compressor needs to come on -- and maybe the invertor will even supply enough power to start up the compressor, but then the genset will start up to take over the load.

Such systems are available off the shelf. Some Cummins gensets, for example, can be delivered with them: http://www.cumminsonan.com/autostart/ and I will bet (too lazy to google it at the moment) that there are some retrofit options out there too.
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Old 14-07-2010, 11:59   #15
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Believe it or not, although I'm a deepwater sailor I lived aboard a houseboat for the better part of 17 years. A gasoline-powered houseboat. With two big Crusader engines and a 7.5KW generator. The boat could do 27 knots wide open, and we were the most active boat in our marina. Overnited at anchor 2-3 nites a week, even in winter when the ice permitted.

I came to know that in the houseboat community generator start-on-demand is a very common setup. I also know that -- especially on a gasoline-powered boat -- this is VERY VERY DANGEROUS. That's why I originally posted three years ago that this scares me to death, and some mindless individual(s) not fully familiar with the risks said "don't be scared".

Spontaneous fuel leaks can and do happen. It takes only a small amount of gasoline, vaporized in the engine room, to create an explosive situation. If you've ever seen a gasoline fume explosion aboard a boat, you'd be a believer. I have....the houseboat behind me blew up, and blew the owner into the water. I've seen the results of other gasoline fume explosions aboard boats. If you're not scared you simply don't know enough to be scared.

The OP said -- after several posts -- that he's planning to install the generator on the after deck. I assume that means above decks, where fumes would pass harmlessly overboard and not work their way belowdecks thru vents or other openings in the deck. That is certainly a better setup than having the generator in an enclosed space but I, too, still don't like the idea of generator start on demand.

That said, I had my first ride in a Toyota Prius last Saturday. Between my house and the restaurant we went to some 2 miles away, the engine started not less than eight times. While this isn't dangerous, it's damned annoying IMHO. Sorry, Toyota, I have had six of your cars in the past 34 years and love your stuff, but not the start-engine-on-demand Prius! And, this sucker even has a battery!!

Bill
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