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Old 14-04-2013, 06:25   #31
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Re: Small 1KW Diesel Generator

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There are a number of small 3.5 to 5 kw AC generators available which use Kubota or Farymann one or two cyl diesel engines. Go to:

Marine Generator Test - Victron Energy

In addition Fischer Panda sells a 3.2 kw DC generator that has an autostart feature
That Fischer Panda is a pretty good model of how not to design a small genset. This is absolutely horrifying: Fischer Panda: The Final Chapter. The multitude of engineering problems with this device are extremely well documented here.

One of the things mentioned in the Sail Whisper blog is that the Kubota 1-cylinder diesels are rated (according to Fischer Panda) for only 1500 hours service life, and cannot be used at rated power for long periods. Fischer Panda told him that anything over 125 amps is "overloading" the genset. That's 1.6kW; less than half of the advertised power of that genset. Yikes.

Other comments on the one-cylinder Kubota engine:

"They used a 2cylinder Kubota. Mine was a one cylinder model. They run at a much higher RPM, and thus produce more heat, and heat is the enemy of mechanical stuff. Mine ran at a crisp 2800rpm, and was so loud even the guys with the reefer units would park elsewhere. It lasted about 3 years, then puked coolant out the top and died. Disposable engine. 7hp commercial rototiller engine I later found out."

Marine Generator. Low revs or high revs?


I like Lloyd's generator very much, much better than the Fischer-Panda. But if I were designing a bullet-proof, trouble-free small genset for cruisers, I would do it somewhat differently. For one thing, I would not use the one-lunger Kubota engine at all, much less at its maximum output, trying to produce 3.6kW of power, which based on all of the above reports seems like a recipe for trouble to me.

I would make it as simple as possible, and I would make it "open source" -- which means (a) designed with the most commonly available, off-the-shelf parts possible; and (b) designed with as many parts as possible which can be easily fabricated in a third-world machine shop; and (c) publish all of the engineering drawings so that parts can be made up in the field.

I would make it extremely simple, and I would significantly derate both motor and alternator for trouble-free and long life.

I would probably use the two-cylinder Kubota and derate it to 1800 RPM or so. Driving with double v-belts an off-the-shelf schoolbus alternator like a Leece-Neville or Prestolite which can be rebuilt anywhere by any third-world auto electric shop. Best of all if the alternator is the same one you are using on the main engine -- then you can keep one whole spare alternator for both positions and Bob's your uncle. Alternator derated to about 70% of its maximum power. Regulated with a common three-stage regulator like a Balmar or Adverc (again, best of all if this is the same regulator you are using on your main alternator -- one spare for both applications).

Power take-off like Lloyd's for refrigeration, hydraulics, dive compressor, etc.

No motor control system at all and no electronics (other than the off-the-shelf regulator). Hand throttle, by cable if necessary (if direct access to the genset is awkward). You watch the current draw and throttle down manually when you need less power. Thus one less complex component to fail.

Heat exchanger from the Yanmar or Perkins parts bin, and mounted in a way that just about any old marine heat exchanger lying around can be used in a pinch (and drawings supplied for fabricating one in a real pinch). Ditto with the water pump">raw water pump and exhaust elbow. Location of all of these parts designed for totally simple accessibility from one side, with plenty of room to get to everything.

Who would like a genset like that?



To my mind, a DC generator really only has one significant advantage -- you don't need an accurate RPM control, and you can vary the motor speed for quieter and more efficient running at lower loads. That is because converting AC to DC or DC to AC is just not a problem if you have a modern inverter/charger, so I really don't think you care whether you are getting AC or DC power from your generator.

Therefore, low speed, heavy duty AC gensets, available off the shelf, fulfill most of this mission. They have simple air-cooled alternators which are rarely used at maximum output. They use simple, heavy duty, low-speed, large displacement, three-cylinder Yanmar or Lugger engines which at max load are still only putting out 50% or less of their designed maximum power.

Northern Lights makes a 4.5kW marine genset which I often drool over. For anyone with space for it (and it's quite small), that is just as good a solution as my Open Source Genset, I think, in most respects. And it would have one huge advantage in being much quieter. Disadvantages are that it is more expensive, heavier, and bulkier, and has proprietary parts. But if you take care of a genset of that type, you will rarely need any parts at all, proprietary or otherwise.
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Old 14-04-2013, 07:13   #32
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Re: Small 1KW Diesel Generator

NextGen out of Jacksonville, FL makes a 3.5 kw genset powered by a 1 cyl Kubota. Weighs 160 lbs. Runs at 2800 rpm. Only 28" long, and 15" height and width. Uses 2/10 gal/hour fuel on average. I have their larger set and have been very pleased.
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Old 14-04-2013, 09:17   #33
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Re: Small 1KW Diesel Generator

I have zero experience with the single cylinder Kubota, but I noticed that Duncan replaced his failed Fischer Panda with another gen which used a Kubota 2 cyl engine. Does this mean that single cylinder Kubotas are junk, but two cylinder versions are reliable? Certainly the two cylinder Kubota in my Onan has been flawless since new.

However, the idea of using mostly "off the shelf" parts has considerable merit, and using identical alternators on both the aux gen and main engine (and presumably identical regulators) is a good idea too.

I notice that the little Honda generators have an excellent reputation, but the air cooled gas engines are less than desirable on a boat. Has anyone ever tried to replace one with a water cooled diesel?
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Old 14-04-2013, 11:25   #34
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Re: Small 1KW Diesel Generator

I have a WhisperGen on board and am sad to see the company fail. When it works, it is magic- quiet as a mouse, with 60A at 12V DC, able to heat the boat comfortably on a cold night, sophisticated controls but... It uses a fire box to operate a heat exchanger at a very high temperature, which requires a copper mesh to distribute the diesel fuel for proper combustion. Mine carbons up in 100-200 hours, requiring disassemble down in the lazerette (it was supposed to last 500 hours). With an uncertain source of parts and a lot of complex parts, I fear it won't last too long, but it sure has been a nice little generator. A big solar installation is the back up plan.
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Old 14-04-2013, 13:31   #35
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Re: Small 1KW Diesel Generator

Found a link to a site quoting on small Kubota engines, if anyone is interested. Remember these are just engines, no transmission or generator attached.
Kubota Diesel Engines For Sale- diesel engine motor.com
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Old 14-04-2013, 16:39   #36
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Re: Small 1KW Diesel Generator

Does anyone know of available third party marinization bits and pieces for the Kubota Z482, I used to buy them in the UK, but the company is gone. As far as I can see all the current ones are OEMed to specific builders.

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Old 03-09-2013, 11:07   #37
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Small 1KW Diesel Generator

Dear Cruisers community,

I am a student and I am doing an a feasibility study of a carbon neutral product that would cater for boat users <1kW.

I am writing an academic document comparing different solutions for 1KW power and i am specifically now looking at diesel generator.

I would be really interested to have your feedback on cost, quality and customer experience in relation with the usage of diesel generator. The most important metrics for me is: once you bought a small diesel generator, how long it last, how much it costs to use and service and any comments you may have. Happy to share my results with useful contributors.

I would like to thank you in advance for your help.

Best regards,

Olivier
London Business School, London, UK
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Old 03-09-2013, 11:12   #38
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Re: Small 1KW Diesel Generator

Quote:
Originally Posted by Olivier8888 View Post
Dear Cruisers community,

I am a student and I am doing an a feasibility study of a carbon neutral product that would cater for boat users <1kW.

I am writing an academic document comparing different solutions for 1KW power and i am specifically now looking at diesel generator.

I would be really interested to have your feedback on cost, quality and customer experience in relation with the usage of diesel generator. The most important metrics for me is: once you bought a small diesel generator, how long it last, how much it costs to use and service and any comments you may have. Happy to share my results with useful contributors.

I would like to thank you in advance for your help.

Best regards,

Olivier
London Business School, London, UK
As far as I know, there are no marine diesel generators of under 1kW. They generally start at 3kW and go up from there, with the average ones being probably 6 - 8 kW.

There used to be a Stirling cycle cogeneration plant called Whispergen, which produced around 1kW of electrical power in addition to heat. The factory in New Zealand was destroyed in the earthquake there and it was never rebuilt.
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Old 03-09-2013, 11:17   #39
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Re: Small 6KW Diesel Generator

Dear Cruisers community,

I am a student and I am doing an a feasibility study of a carbon neutral product that would cater for boat users <6kW. I am just changing the level of power - I apologise for that. My question remain the same for small 6KW diesel generator. I would be interested to know what you are using the small diesel generator for.

I am writing an academic document comparing different solutions for 6KW power and i am specifically now looking at diesel generator.

I would be really interested to have your feedback on cost, quality and customer experience in relation with the usage of diesel generator. The most important metrics for me is: once you bought a small diesel generator, how long it last, how much it costs to use and service and any comments you may have. Happy to share my results with useful contributors.

I would like to thank you in advance for your help.

Best regards,

Olivier
London Business School, London, UK
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Old 03-09-2013, 12:14   #40
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Re: Small 6KW Diesel Generator

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Originally Posted by Olivier8888 View Post
My question remain the same for small 6KW diesel generator. I would be interested to know what you are using the small diesel generator for.
The smaller generators tend to be used to charge the battery bank, maybe running only one hour per day. Most of that energy went into the refrigeration system, although not all cruisers run refrigerators.

Larger generators are often used to provide air conditioning, especially on powerboats.

In terms of sailboats, more and more of us are using solar panels and/or wind generators rather than using diesel generators.

The larger the vessel, the more likely it is to have a generator installed.
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Old 03-09-2013, 13:04   #41
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Re: Small 1KW Diesel Generator

Oliver,

I suggest you go to the Southampton Boat Show starting in a couple of weeks and speak to the manufacturers and importers.

Pete
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Old 03-09-2013, 15:11   #42
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Re: Small 1KW Diesel Generator

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Diesels under 10hp are almost non existent, and for a 1kw generator you would want I am thinking around 3.5hp.
15ld225s - lombardinigroup.it

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Old 04-09-2013, 06:38   #43
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Re: Small 1KW Diesel Generator

I purchased a MASE 2.5 KW diesel generator from a gentleman who was repowering his trawler and have yet to install it into my 43' cutter. It is small and relatively light, weighing just over 100 lbs. You might look into the MASE line of generators.
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Old 04-09-2013, 06:57   #44
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Re: Small 1KW Diesel Generator

Dont know where you would get/keep the feedstock,but checkout :Free plans for a FEMA "gasafier" This will reduce your Footprint..
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Old 04-09-2013, 07:17   #45
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Re: Small 1KW Diesel Generator

A hint: Anything Diesel powered is going to be heavy, due to the nature of its combustion; "much thicker and heavier block/cylinders". An auxiliary Diesel powered generator on a sailboat...is as rare as chicken teeth!

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