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Old 10-03-2009, 08:08   #1
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Looking for information on building my own genset

After looking at the prices of a 3-5Kw genset and shaking my head... I have decieded in my spare time... oh year sure... to research building my own diesel genset.
Requirements are to be able to run 2 ac units at the same time, or charge batteries and make water. The watermaker as well will be home grown.

Base power to be supplied by Kubota Z482, which supplies 13HP at 3600 rpm, but I will depower it a bit for longevity so figure on 8-9 HP.

I am currently looking for new ones, and have found one in England that would cost ~1500 usd delivered. In the USA, a new one is ~2500 give or take plus shipping. Also there are many available used, and I am looking at those as well.
There will of course be costs involved with marinizing it, adding heat exchanger, exhaust, etc.

The Generator head is where I am currently stumped. There are many out there at around 500 USD for a 5Kw unit, but don't think they will hold up well in the enviroment that it will need to operate in. There is a very interesting one 186PMG but am researching where if possible to purchase one. They are available in Australia, but the wrong phase and hertz.

Any help on this would be appreciated. As I consider myself a do it yourselfer, I really don't want people feeling the need to talk me into buying a 6K to 12K unit becasue thats what they did. I understand that they are out there, but really don't have the desire for that. I would not install one before I paid that price for something I think should cost roughly 2500 bucks installed by my self.
I plan on changing out my 1500 w watt inverter for a 3000 watt victron inverter charger to help with start up loads and such. I have 880 amphours of batteries. The air conditioning units will be 16,500 and 12000 btu. Mostly at night the 16,5 would be the only one running.
I have a CO detector.
The unit will installed so that there will be very little to no sound, so the I don't want you anchored near me replies can be left out thank you very much...

Have some insight on this ?

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Old 10-03-2009, 08:28   #2
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Why not buy a used boat generator and rebuild it? It will be a generator that has already been engineered for a boat and all the parts will be available by purchasing a rebuild kit. This sounds like much less hassle than building your own from scratch and is probably around the same price.

Besides, the noise enclosure will fit perfect.


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Old 10-03-2009, 09:01   #3
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Just a thought, I have seen lots of small and portable generators on ebay. They cost about $150.00 new. Some of these are two cycle and others are four cycle.
Also Honda makes several generators for about $500, some with electric start. Maybe one of these could be made to work for you.
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Old 10-03-2009, 13:18   #4

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Sam, cheap gensets are often disposable crap made in China from scrap metal. They're designed for emergency use,i.e. once or twice a year during a storm outage, or a camping weekend, and that's all.

Bob, try looking for US military surplus gensets. Like anything in the surplus market--there are bargains to be had and sometimes, not. A friend of mine bought one in two consignments (generator head from one party, motor from the other) and the hardest part was getting the two lines up to bolt together. Built rather heavy--very different from China Trade stuff.
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Old 10-03-2009, 13:52   #5
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Those Honda ultralight/ultraquiet generators are amazing. I spent about $500 for one a few years ago, and it performed flawlessly. Most people carry gas onboard for their outboard anyway, so the fuel isn't really a concern in my book.

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Old 10-03-2009, 15:35   #6
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First you may have to convert your entire requirement into W, VA, or A.
A 5 KW is around 20A 240V or 40A 110V
I doubt than a 5kw will be able to start a second ac units. You should find out this from manufacturer data sheets.
To run an AC generator with an inverters require that they can synchronise with each other and share the load. This is complicated stuff and inverters who can synchronise with the electricity supply are not cheap.
An 1100 inverter will just start an ordinary 140 l freezer rated at 240V 0.8A.
Aussie stuff can often get converted to 110V 60Hz but I believe will be cheaper to buy in the US.
A Perkins K1000 cost around 4000 OZ
A marinizing kit for above from Sabre 2000 OZ
A 2 pole 3000 rpm 5kW generator 800.
I spent 10 500 $ building my gen set, but it is more complex, 7000 would have been the minimum.
Be careful you can spend a lot of money and have nothing at the end.
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Old 10-03-2009, 22:38   #7
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Nice generator.

Hellosailor, the military surplus sounds like a good idea, but not sure the diminsions would be right.

One of the PO had a gas genset at one time on the deck near the mast. There is wiring for it and a plug on the mast base, and a transfer switch. I don't want to go that route. But I could, and am looking into using the Honda eu 2 or 3k. But of course it would be louder, vibration would be more, and there is the PIA of using gas vrs diesel.

I am thinking of a small kubota engine, 13 hp, I can change it to fresh water cooling with a heat exchanger, a waterlift muffler. But the generator head is the place I am not sure of. How to mate it to the engine, and then to control the engine for the proper voltage and hz.
Also want a power take off for a CAT pump for a watermaker project.
I ordered the back issue of good old boat where someone built there own watermaker. Hoping somone here has done the genset thing.

A new kubota engine is available in England for just over a grand, and a 5.5 kw gen for 500 on ebay, I figure another grand to install it and that is 2500, over half what a nextgen would cost.'
I was going to just put in a windgen, but figured that if I could pull this off, for not much more money I would have a more robust system.

Chala, the victron 3kw inverter charger will share the load with a genset, so that it will help, up to the 3000 watts the inverter can supply for start up loads. Depending on the draw of course. My flagship 16.5k btu ac draws 11.3 amps cooling, but the start up is of course 2 or 3 times that. The victron will help supply the difference from the batteries.

Very much still in the planning stages and I appreciate all your comments.
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Old 11-03-2009, 03:06   #8
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Well one of the benifits of working the night shift is the ability to read a lot.

Now rethinking the whole honda generator thing.
Maybe it might work for us in the short to medium term.
Anyone have the 3000 watt honda ? or the other choice is 2 of the EU2000i generators working together when we want to cool down the boat and single for charging with the inverter to help balence the load.

Think I will have to go to the honda store in town and take a look at it.

Whats the lifespan of these honda generators when subjected to the marine enviroment?
And on a plus side could use it at home to power some small things in case of a outage/hurricane.
So many choices......
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Old 11-03-2009, 03:34   #9
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I have no idea as to what size motor is needed to run this but it might be worth a look. Just something I found when looking around the other day. ENERGO-TEC
I used to be undecided but now I'm not so sure.
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Old 12-03-2009, 23:41   #10
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Thanks. Won't work for me though.
The unit I am considering will output 4Kw. A kubota 13hp will run it fine with juice to spare I hope for a CAT pump for the watermaker.
Just need to hunt up the parts. Looking on ebay now for what I need.

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