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Smallest Diesel generator

 
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So I have wondered for a while just how small one can practically make a Diesel generator.  I can easily find a Generac 5k model that does have nice fuel sipping qualities.  I was wondering if there is something even smaller like a 2k generator or even an inverter generator for making just enough power to run a little cabin?

Eric
 
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Northern Tool has a belt-drive generator head rated at 2.6 kW for $399.99.  The more difficult find is the engine....but it appears easier these days here in the US to find ~10 hp pull-start air-cooled imported diesel engines for under $1,000.00, although I can't speak to their quality.
 
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The inherit higher minimum required quality (cost) of a diesel engine goes UP as they get smaller.  It means a small generator isn't very economical to build.  RV's and semis with aux power to run the AC at night have made them more available, but more like ten kw, not two.

The cheapest way I know to do it is get a yanmar engine from one of the Japanese used imported tractors. I have seen them for under a grand with low hours in the teen hp range.  Basically the frame rails from radiator to flywheel from a tractor with a bad tranny.  I want to get one and add that northern tool generator head plus an air compressor pump.  
 
Eric Hanson
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John, R,

Yeah, I kinda thought that going down in size was going to go up in cost.  Occasionally I get a wild hair—just a weird fantasy of mine—to spend a winter deep in the Alaskan bush (I absolutely love snow!) but I still want some creature comforts.  My thought was to basically run a diesel electric system and mostly use batteries to run some lights and a few electronics.  As the battery bank runs low I would run the diesel to charge up the batteries.  

I am not going to do this little plan, I was just thinking about how it might work.

Eric
 
John Weiland
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I've never had an air-cooled diesel engine, but I've always wanted one and on occasion will make a purchase like that if the price is right.  I've liked the NorthStar gensets, both PTO tractor-driven and otherwise, and would probably buy a generator head from them if I wanted the extra back-up power.  But I might also set up the engine itself to be used for powering multiple items, the generator being only one of them.  Seems like Yanmar and some of the Chinese makes are more available as single-cyl air-cooled pull-start items through eBay and elsewhere, so I've not given up on the idea.  Good luck on what you decide to do!....
 
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Kubota makes a 4500 watt, diesel generator. It was the smallest I could find, but was not too bad in price: $2375.

I have the equivalent of a NorthStar PTO Generator, mine is 20 KW and runs my whole house when the grid goes down. It puts a few extra hours on my tractor, but my tractor is always running too, and maintained, so it is always available for back up generator work.

For your cabin, you could put in radiant floor heat, find a liquid cooled generator, and have co-generation; the coolant cools the engine and heats your cabin, and the generator of course produces electricity. In the summer, shut the valves going to the floor and just use the engines radiator to cool the motor.
 
Travis Johnson
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Here is the link for that 4500 Watt air cooled Generator...

4500 Watt Diesel Generator
 
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Used construction equipment auctions.   Mobile light plants. They use a 3 cly diesel, liquid cooled. The lights are useless unless you have a big function in the back forty some night. But without the lights on, they run & run & run.
We use them all the time on job sites as portable generators. I see them listed at auctions all the time for less than $1000. And they have a 2" ball hitch and tow anyplace.  
 
Eric Hanson
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Travis,

Thanks.  I too have looked at PTO generators.  I decided against one as it requires my tractor, and therefore would not be able to use the tractor and generator at the same time.  

Typically I think about using a generator when we have winter storms.  I would want to run my tractor, likely to clear the 450’ driveway.  I would want some electricity at the same time and my generator provides that part.  Also, the last time I looked at a PTO generator, the price was about twice that of my Generac, 5.5k generator which does not run everything, but run enough for me.

Eric
 
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I had a Kubota 4.0 hp marine diesel DC genset with a large frame alternator to charge batteries. And water cooled to heat a hydronic floor doing cogeneration of electricity and heat. I sold it reluctantly because it was sitting outside not getting used and I decided to downsize and hit the road. I thought about taking it with me on my trailer but the solar does such a good job it wouldn’t get used enough to make it worthwhile. I don’t think Kubota makes these particular ES-300 marine units anymore but they are available used occasionally. They run at 1800 rpm and have a big flywheel. That’s important on a small diesel.
There was a blog by a guy in Canada, solarhomestead.com, who used a 10 hp diesel runnng a old externally regulated Motorcraft 100 amp alternator direct to his deep cycle batteries with no regulator. He ran it full field for a hour or so to “bulk” charge. Then he topped off the batteries with solar. Simplest system I’ve ever seen.
 
Travis Johnson
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Eric Hanson wrote:Travis,

Thanks.  I too have looked at PTO generators.  I decided against one as it requires my tractor, and therefore would not be able to use the tractor and generator at the same time.  

Typically I think about using a generator when we have winter storms.  I would want to run my tractor, likely to clear the 450’ driveway.  I would want some electricity at the same time and my generator provides that part.  Also, the last time I looked at a PTO generator, the price was about twice that of my Generac, 5.5k generator which does not run everything, but run enough for me.

Eric



I understand, but here are a few additional points, but please, please, please do not think I am trying to convince you of anything, just giving you additional ways to look at a PTO generator.

For me, shutting down the generator for an hour or two to go plow snow is not going to kill anyone in my family. The house will not get cold. Life will go on, and I can schedule when I plow snow at my convenience.

Another thing that is nice is, a PTO generator has Clean Power. That is huge because a small portable generator does not have that capability. Nothing in my house is going to burn up, or blow up because of unclean power.

It does not take much to power a PTO generator. While designed to be powered by a PTO, something as simple as a flat leather belt, encircled around the rear tire of a jacked up old truck, with a stick pressing on the gas pedal at the right RPM will get you power. Yeah that is 100% redneck, but it would work, and we are not talking a little bit of power, but enough to power your whole house.

Or buy an old tractor that has a working engine and PTO and nothing else.

I even thought about making a set of rolls for mine so that I can drive my car or truck onto the rolls, and power the PTO with whatever...tractor, car, SUV. Put whatever onto the rolls, put it in gear, and power the generator that way. You see what I mean, it does not take much to power it by something other than a tractor. But for very little money, you get so much power. Mine is 20 KW and costs around $1500 new. My parents bought a Generac and it was close to $7000 installed for 14 KW. I got about $200 in mine. It was given to me, but was missing the PTO shaft. A PTO shaft was $180, and then I replaced the oil in it, and bought a quart of paint to paint it.
 
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I've got an ETK 5 kW diesel genset with electric starter that we picked up six years ago because we keep a lot of food (especially meat) in a couple of chest freezers and our region is prone to occasional power cuts that have the potential to last for well over a day. It's a pretty run-of-the-mill Chinese air-cooled 6 HP motor spinning a single-phase AC induction gennie. I think this is the most common configuration you will find in the low end, and it means that the AC power will be relatively "clean" (pure sine wave) albeit prone to frequency wobbles, as it's only as good as the RPM governor on the motor. The next model up is a 3-phase unit, same engine and output power. These are cheap, but not nasty and it's gotten us through several multi-hour outages including being able to carry on with working remotely.

Things I now know about this type of genset:

1) It is freaking LOUD. As in you really need to be wearing ear protection if you're anywhere near the thing. If I keep it as our main backup I will eventually build a little insulated shed next to the garage to house it, and run a long duct around the back for the exhaust. On the times that we had it running in order to keep working, I was really jealous of Sharon's office location upstairs and on the side of the house opposite the garage. With my window shut, and with my nice headphones on and music playing, it was still annoying as all get out.

2) You need to keep the battery topped up. I'm probably going to get a little trickle charger for this purpose, maybe a small PV panel. I originally was pretty good about starting and running it every three months to try and maintain the battery, but this was not really good enough and if the power failed right now I would need to jump it from the car to get it going. Because...

3) A 6 HP diesel motor is not something you want to start with a recoil rope. I nearly dislocated my arm when I tried. There is a decompression valve that you need to engage, and the manual says to use two hands. I would say use two burly dudes (I'm not as strong as I used to be but I can still swing a 30 kg feed sack onto my shoulder to carry it across the paddock).

4) Think about how you will actually connect it to your residential supply. There is a proper way to do this, and there is also a "suicide lead." You absolutely MUST disconnect from the power company grid any time you have backup power involved. If you somehow fed mains current out to the neighbourhood, someone working on the lines could get killed if they didn't check first. If you don't have an automated solution to manage this, make a checklist and follow it every time you switch to backup and back onto mains power. Sequence of steps is important: Turn off your main breaker (or pull the fuse) first when going to backup power, and turn it back on as the last step when returning to grid life.

5) Understand the sizing of generators and types of loads. We can run our household pretty handily on 5 kW, but I would never try cooking an elaborate meal using the electric stove, doing a load of laundry, and plugging in resistive heaters all at once. If you have a big inductive load like a central heat pump/AC unit, the startup current draw from the compressor could be too much for the system. Big motors are the thing to look out for.

6) Keep your fuel fresh. Diesel can deteriorate in storage, especially if there is water (usually from condensation) in the tank. Add a little fuel conditioner if you don't go through it in 6-12 months' time. Check and clean filters. Change the oil at manufacturer's recommended intervals.

If I did it all over again, I probably would have gotten a smaller, maybe 2.5 kW petrol model. Quieter, more realistic to start by hand, and still enough to take care of our basic needs. The present one could power two or three homes in a pinch if we needed to.
 
John Weiland
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As a user of both a PTO version generator (7 kW) and a couple of gas-powered portable gennies (9 kW) I'll just add some other options to what Travis and Phil have mentioned.

I've not run the PTO version on an 'American' tractor for very long.  This is because the Yankee versions generally are single speed PTO (at least in the smaller HP) and you are winding the engine pretty high to reach the expected rpm on the generator in order for it to be powering properly.  For that reason, I tend to use our grey-market Yanmar (19 hp diesel tractor) that has 3 PTO speeds, the middle of which allows the generator to operate at a lower engine speed.  It may be that under severe electrical loads it might be better to run it at the higher rpm, but I'm not sure....maybe others know the answer to that.

The gas portables have their pluses and minuses.  Truthfully, I've used them very infrequently....and I thank the above average service and reliability of the local rural electrical coop that provides our power for that fact.

With regards to

--batteries, I've decided it's not worth messing around with dead batteries and just end up keeping a few 12V lawn tractor batteries in a topped off state.  In the summer, these are naturally in the riding mower or other small powered equipment that is in use for that season.  In the winter, they are lined up inside and charged occasionally to ensure that *someone* is ready to go if needed. (And unlike Phil's diesel, the gas pull start is relatively easy if this option is required.)  But the nice addition to this is the "pop-top" style of battery connector (photo below) that can be found at many hardware and automotive stores....and that I now use on almost all vehicles in the fleet except for our cars and trucks.  They just make changing out a battery that much easier.

--fuel, I've placed stop-cocks in-line with the fuel line that allows me to drain the tank of the portable gennies.  That way I don't have to worry about wasted bad gas and the varnishing that it can do to the carb.  Both have cost me money in replacement and repairs.

--electrical loads, I've placed labels next to specific breakers in the main panel that control 'amp hogs'.  When I need to power the house with the generator, I turn off anything that would need a lot of power and has been labeled ahead of time as such.  The power company has installed a transfer switch (mechanical, not automatic) that disconnects the coop service from our house when I'm using the generator.  A 30A 4-pole plug/cable tethers the gennie to the transfer switch to provide power to the house.  Main concern is that the well pump is still powered during an outage,.....second priority is the furnace (in winter).

Like many other items on the homestead, the generators on ours sit for long times with no activity.  Unfortunately, it's for that one time when they are badly needed that keeps them around.
PopTopConnector.JPG
[Thumbnail for PopTopConnector.JPG]
 
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ive seen modern diesel 2kw military surplus generators on iron planet auction site
 
Travis Johnson
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I have got a strange generator kicking around...it is a 3000 watt, either 1 or 3 phase generator (your choice), gasoline or propane (your choice) liquid cooled generator.

DSCN0747.JPG
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Eric Hanson
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Phil,

I agree with you emphatically and wholeheartedly regarding the connection to the house.  After I bought my present 5k Generac, I bought a dedicated transfer case.  It wires directly into the main breaker box on a circuit by circuit basis.  I can selectively switch over 8 circuits from main power to generator power one by one.  I still have two remaining circuits unassigned for future applications (For a total of 10 circuits).

Significantly, these transfer switches are the Break-Before-Make type so that it is impossible for me to send electricity out and down the line.  I can’t accidentally kill a lineman by flipping the switch out of order. I paid to have the transfer switch professionally installed.  Actually, the installation plus the switch cost more than the generator, a minor, trivial cost compared to the life of a lineman.  

I have seen people wire in a simple plug from the generator to the house and manually shut off the main power.  This will function normally, but is terribly dangerous as if for any reason someone turns main power back on before turning off or disconnecting the generator, they will sent a burst of electricity down the main power line.  Likely, it will be a short lived burst as the power draw down the line will likely trip the main circuit breaker on the generator itself.  But should a lineman be working on that line, he will get a nasty, potentially fatal jolt of electricity before the generator trips.

Lastly, most portable generators connected to the house should have their own dedicated ground.  I did not know this until after I bought my generator.  The solution was pretty simple.  I got a dedicated ground rod (copper jacketed steel core rod with a sharpened point at one end).  I pounded this near the same point as the main electrical ground.  I have a little wire with clips on the ends that runs from the generator to the ground rod when I am using the generator.  Many portable generators are purchased for home backup require this and many people are blissfully unaware of this need.  There are generators that don’t require this extra step, but as they are more expensive, not nearly as many people buy these types of generators.

At any rate, thanks Phil for bringing up this very important point.

Eric
 
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The smallest diesel generators we get are from the road side signs.  We get them cheap when they get ran over.  I gave about $150-$250 for them. I've got 3 of them off of craigslist that all had been ran over.  I just torch the engine skid right out of the tangled up mess.  All of them have ran good for me.  The little lombardini sips fuel.  They usually have an electric starter and are pressure lubricated.  They also come with a bracket that matches the 10si gm alternator.  You can get a 12 or 24 volt alternator that fits from the local auto parts stores.  They run good off of vegetable oil when they are wormed up. When buying antique diesel such ass lister or peter we usual give $100 per hp.
 
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