Choosing a good generator

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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #92
    Re: Choosing a good generator

    i think i will agree with you on the oil filters being a good idea. the oil is still good, but it just needs the particles filtered and oil these days is getting up there in price.
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  • swmspam
    swmspam Solar Expert Posts: 57 ✭✭
    #93
    Re: Choosing a good generator

    Problem is, the Generac engines are the only 1-cylinder engines available with pressurized oil systems with filters. Otherwise, you'll need a 2-cylinder from Honda, Briggs & Stratton, or Kohler. Those all have pressurized oil and filter. I might have a chance to meet with Lombardini (who are now owned by Kohler) this month for work. The meeting will be about their integrated engine/alternator kit they developed for series hybrid vehicles. Maybe I should ask if I could have one, too ...

    Water cooling is very interesting. One could re-direct the coolant from the radiator to a heat exchanger indoors. Cogeneration! Problem is, water cooling is only available on larger engines, typically starting around 1 liter and usually 3 or 4 cylinders. That's a little overkill for my targeted 6kW. Just for example, a 6kW generator operating at 15% efficiency (approximate) will create about 40kW (136,000 BTU/hour) of waste heat. My house needs about 45 BTUs per square foot in the midwest winter for a total 135,000 BTU for the whole house. If I can recover 50% of the waste heat of the generator, that would contribute ~70,000 BTU to my heating needs. Now the generator is operating at a far greater efficiency, utilizing a much greater percentage of the fuel's energy. Even my little Yamaha EF2000iS blows off enough heat for the family room, but we'd rather stay alive. So I watch it on my back deck wistfully dreaming about all that heat keeping me warm indoors instead of melting snow outdoors.

    My "dream system" would be a 2-cylinder, about 700cc, runs on gasoline or natural gas, has water cooling, and a pressurized oil system with oil filter. Couple that to a 6kW heavy-duty generator head rated for prime power, and I'm set. But then I'd have to pipe the hot water and heat exchanger through walls and to an air blower. I hate plumbing. Ugh. So I'll file this in the "dream" category and go on with life ...
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #94
    Re: Choosing a good generator
    swmspam wrote: »
    Problem is, the Generac engines are the only 1-cylinder engines available with pressurized oil systems with filters.

    Only the Generac OHVI engines. All the GP-series are Chinese built splash lubed.

    Really, there is nothing inherently wrong with splash lubed engines. They have been around since the dawn of the industrial age and are simple and dead reliable. Tell me - how many Honda GX's have you seen with a windowed block because it tossed a rod? I'll bet not very many.
    --
    Chris
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #95
    Re: Choosing a good generator
    swmspam wrote: »
    Water cooling is very interesting. One could re-direct the coolant from the radiator to a heat exchanger indoors. Cogeneration! Problem is, water cooling is only available on larger engines, typically starting around 1 liter and usually 3 or 4 cylinders. That's a little overkill for my targeted 6kW.

    Yes! Co-generation is very interesting for off-grid use, surprised it's not more common place, especially for solar based systems, because the times you need to run the generator are generally the same times you need more heating. The cooling system is one source of heat, another is the exhaust. As long as you don't cool the exhaust too much and are careful about condensation of the exhaust gases and to not restrict the exhaust flow you can get a lot of heat from it.

    Perkins do small (<1 liter) 2 cylinder diesel's that operate at 1800rpm and are water cooled: http://www.perkins.com/cda/files/2077967/7/402D-05G%20Electro%20Unit%20PN1954.pdf
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #96
    Re: Choosing a good generator

    There are all kinds of Marine Generators liquid cooled just waiting to be hooked up to a water supply. Onan has made all kinds over the years with a 1 & 2 cylinders. They can usually be picked up for a song around any Boat repair yard used.
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #97
    Re: Choosing a good generator

    Visit Bob Golding's microcogen forum. There's all kinds of people that do it.
    http://www.microcogen.info/

    --
    Chris
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  • swmspam
    swmspam Solar Expert Posts: 57 ✭✭
    #98
    Re: Choosing a good generator
    stephendv wrote: »
    The cooling system is one source of heat, another is the exhaust.

    I saw that Polar Power makes an exhaust heat exchanger for this purpose. I haven't done all of the calculations to show where the waste heat is concentrated - what is the distribution of waste heat coming from the engine block vs. exhaust gasses?

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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #99
    Re: Choosing a good generator

    Roughly 30% thermal efficiency, 30% goes to cooling and lubrication systems, 40% goes out the exhaust.

    Turbocharged engines can recover some of the exhaust heat loss and use it to improve thermal efficiency.
    --
    Chris
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  • swmspam
    swmspam Solar Expert Posts: 57 ✭✭
    #100
    Re: Choosing a good generator

    I messed with my Yamaha EF2000iS. I calculate it converts about 15% of theoretical gasoline energy content to electricity. The remainder is waste. Since my gasoline may contain 10% ethanol, it's not exact. Some of the waste is unburnt fuel or high-energy compounds (such as CO) in the exhaust. Some of the waste is electrical heat in the alternator and inverter. So I piped the exhaust fumes away from the generator and used my "thermometer" (otherwise known as "putting my hand in the hot air") and subjectively noticed the air-cooling pathway contained a lot more heat than the exhaust. OK, so that's not exactly scientific.

    But it sure sounds easier to heat-exchange from an exhaust pipe than install a water jacket. It would also silence the exhaust, too. Too much work, at least for now, until I really need it ... anyway, mine will be a portable unit (Honda EU6500iS). Unless I convert the portable unit into a stationary system, it makes cogeneration a moot point.
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #101
    Re: Choosing a good generator

    When we got our Honda generator I was curious as to how it would compare against the LP fueled EcoGen. I ran it on a real-world battery charging job for 2.5 hours.

    I don't have a good way to measure genset power production directly on a variable load (yet - I'd like to pick up an old utility kWh meter), but I can measure on the DC side going into the batteries with very good accuracy. I put 6.0 kWh into the batteries in 2.5 hours, which at 90% charging efficiency (estimated) I figured to be about 6.7 kWh at the genset. There was other loads on in the house at the same time, and I estimated those at about 370 watts ave for the 2.5 hour run, which would be another .9 kWh direct from the genset at Power Factor 1.0. That would be a total of 7.6 kWh produced by the genset over 2.5 hours, or roughly 3.04 kVA average output for the run.

    The generator burned 141 ounces of 91 octane (non-ethanol blend) fuel for the 2.5 hour test. That figures out to a fuel consumption rate of .44 gal/hr. The BTU content of the fuel is about 114,500 BTU/gal, or 33.56 kWh/gal. So overall efficiency figured out to 20.6%.

    That's about 3% better than the LP fueled EcoGen could do. Some diesels will achieve 3-4% better than that. But I was pretty happy with it.

    I did some measured fuel consumption tests on various generators over a year ago. The inverter types (I tested both Honda and Yamaha) were invariably less efficient (~2%) than a conventional driving a fixed resistive load. I chose to use the resistive load for testing because it simulates battery charging during the bulk stage pretty well. And was a more controlled load than a real world battery charging job, so the different generators could be accurately compared.

    Looking back in my test data, the Yamaha EF3000iES that I tested achieved a best efficiency of 13.5% @ 2.292 kVA output and 57,982.3 BTU.h input. I had also tested a Honda EM4000SX. The Honda was too big compared to the other generators I tested, so it could not reach anywhere close to its peak efficiency because it wasn't loaded heavily enough. But the Honda did 15.5% @ 2.292 kVA output and 50,324.3 BTU.h input.

    Edit:
    The data from my generator testing is attached for reference. The diesel Yanmar was the most efficient of the bunch overall. But the little high compression Champion generator could beat it. But here again, the Yanmar, like the big Honda, was operating at well below what it could achieve because it's a bigger generator. The Yanmar had incredible surge power, right on par with the big Honda. The cheap Chinese generators were pretty darn good overall - they're basically Honda clones. The inverter types were pretty good at lower loads. But when you add load to them they fall behind the conventional excited wound field generators.

    I also tested each generator to see if it would produce its rated continuous power and rated surge capacity, although the results of that are not shown in this data. The Honda's, Yamaha and Yanmar all passed with flying colors. Neither of the Chinese generators (Champion and Generac) would produce rated power, nor rated surge. The Generac was close but no cigar. The Champion was woefully short by almost 1 kVA and was pretty much running at it's full maximum continuous output at 2,300 watts. Loaded any heavier and it had a lot of governor droop and wouldn't maintain either voltage or frequency. It was so bad that if I tried to increase load on it the voltage would drop as fast as the amperage would increase, with the net result that it didn't put out any more power.

    Attachment not found.
    --
    Chris
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  • woozy
    woozy Registered Users Posts: 7 ✭✭
    #102
    Re: Choosing a good generator

    I put a tri-fuel kit on my Generac 7550. I like having a fuel source on my own property. As we've seen this week, even a relatively small regional disaster interrupts the gasoline supply. If it was national, we'd not see a drop for a very long time. And natural gas...a lot of things besides earthquakes would interrupt that. If the grid electric is down, so is the natural gas.

    I'd love to have a tri-fueled Honda.
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #103
    Re: Choosing a good generator

    I'm of the school of thought that it's better to have two generators that run on different fuels than to have one that runs on multiple fuels. It not only provides multi-fuel capability, it also provides redundancy in the event one would fail.
    --
    Chris
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #104
    Re: Choosing a good generator
    ChrisOlson wrote: »
    I'm of the school of thought that it's better to have two generators that run on different fuels than to have one that runs on multiple fuels. It not only provides multi-fuel capability, it also provides redundancy in the event one would fail.
    --
    Chris

    it seems to me that if your propane genny were to fail and all that's left is your gasoline genny and the gas stations have no power or gas, then you are still sunk. maybe for redundancy it would be good to have 2 gennies capable of multi fuels.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #105
    Re: Choosing a good generator
    niel wrote: »
    it seems to me that if your propane genny were to fail and all that's left is your gasoline genny and the gas stations have no power or gas, then you are still sunk. maybe for redundancy it would be good to have 2 gennies capable of multi fuels.

    It comes down to "how much redundancy is enough?" One gasoline generator with a can of fuel will do for most power outages. If it gets to be armageddon it won't matter if you have ten thousand generators in varieties ranging from gasoline to multi-fuel to alcohol.

    You can not plan for every possible contingency. All you can do is look at the history of your area and plan for what is the most likely catastrophe to strike.
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #106
    Re: Choosing a good generator
    ChrisOlson wrote: »
    I did some measured fuel consumption tests on various generators over a year ago. The inverter types (I tested both Honda and Yamaha) were invariably less efficient (~2%) than a conventional driving a fixed resistive load. I chose to use the resistive load for testing because it simulates battery charging during the bulk stage pretty well. And was a more controlled load than a real world battery charging job, so the different generators could be accurately compared.

    this is very good, Cris! ...
    I like people who have concerns and invest time in making stringent and precise tests to have a criterion based on how things really are! ... lol
    sincerely congratulate you and too, I thank you!...;-)
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #107
    Re: Choosing a good generator
    niel wrote: »
    it seems to me that if your propane genny were to fail and all that's left is your gasoline genny and the gas stations have no power or gas, then you are still sunk. maybe for redundancy it would be good to have 2 gennies capable of multi fuels.

    I agree with 'coot here - your gasoline generator should be the primary. Gasoline generators are inherently more efficient than propane (except really exotic engines with high compression, modified valve and ignition timing, etc.). It's not too hard to have a full tank in the generator and an extra 10 gallons on hand for it. And if you have to you can siphon some gas out of your car or truck for it. It it fails or runs out gas, then break out the propane one.

    If you run out of fuel for both, gasoline is going to be easier to find than LP gas. A gasoline engine will even run on moonshine (some of us have stills hid back in the woods) if you leave the choke on. LP won't.
    --
    Chris
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #108
    Re: Choosing a good generator
    unicornio wrote: »
    this is very good, Cris! ...
    I like people who have concerns and invest time in making stringent and precise tests to have a criterion based on how things really are! ... lol
    sincerely congratulate you and too, I thank you!...;-)

    Basically what we did was got hold of a bunch of generators, hooked them up to water heater elements and tested each one with a metered quantity of fuel. We ran the generators until they were warmed up and ran out of fuel, then hooked up our metered container, turned the fuel valve on, and the generator that that amount of fuel to power the load against the clock. The one that runs the longest wins.

    The Yanmar diesel was a bit of a pain because it wouldn't start after we ran it out of fuel. And I lost a tiny bit of fuel bleeding the air out from the pump to the injector. So the results are a little skewed on that one and it would've done better.

    The Generac was junk and smoked us out of the shop. Before I tested it I pulled the head off it and fixed the valve guides because they were so loose I think the valves hit one side of the seat and bounced back and forth before they fit in the hole to shut. I don't know how that thing even ran. But it did pretty good on the test. It was an older GP3250 that was 120 volt only. All the new ones are 120/240
    --
    Chris
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  • swmspam
    swmspam Solar Expert Posts: 57 ✭✭
    #109
    Re: Choosing a good generator
    ChrisOlson wrote: »
    I did some measured fuel consumption tests ...

    Great data! Thanks. I appreciate real-world experience and data. You bring both to the discussion.

    I can debate the fairness of using Diesel in the comparison, having such an obvious superiority. But, Diesel is a problem for me. The station down the street carries it. It's easy to obtain around here. I could store some, but I don't have a vehicle that burns it. Therefore, I wouldn't be able to rotate stock unless I burn it in the generator. With the prices I'm looking at (the Honda EU6500iS is $4000), this is entering Diesel territory. Basically, at this price point, both stationary and Diesels can be considered. I agree that gasoline is the ubiquitous fuel, but Diesels are great. No spark plugs or carburetor. Magnitudes lower CO exhaust. Robust and reliable. Runs for decades. But the Yamnar is not portable.

    But that's why I'm looking at the Honda. Good engineering compensates for much of the fundamental inferiority of gasoline. But you pay for it.
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  • mtdoc
    mtdoc Solar Expert Posts: 600 ✭✭
    #110
    Re: Choosing a good generator

    The nice thing about the tri-fuel kits is that you can run on gasoline yet have the ability to run on propane in an emergency situation. If you run out of both, well then fire up the still and feed it some moonshine! Maybe they should be called quad-fuel kits.:p
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #111
    Re: Choosing a good generator
    swmspam wrote: »
    But that's why I'm looking at the Honda. Good engineering compensates for much of the fundamental inferiority of gasoline. But you pay for it.

    Diesel fuel is currently 65 cents more/gallon than gasoline. The cost/kWh with diesels is too high because of that, even with their superior thermal efficiency. You might not have spark plugs or carbs. But you got injection pumps that are VERY sensitive to water and I've seen more than a few Yanmar and Hatz diesels with a seized pump plunger because of being fueled out of a can and water got in it. You can buy a whole Honda gasoline engine for what it costs for a new injection pump on a Yanmar or Hatz.

    When you buy a Honda you pay extra for the reputation, reliability, engineering and dealer support. Something you don't get from most other companies.
    --
    Chris
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  • swmspam
    swmspam Solar Expert Posts: 57 ✭✭
    #112
    Re: Choosing a good generator
    ChrisOlson wrote: »
    Diesel fuel is currently 65 cents more/gallon than gasoline. The cost/kWh with diesels is too high because of that ...

    I'm looking at $4000 ~6kW generators. If I also bought $4000 of fuel, I'd end up with 2,242 hours at 50% load using gasoline (using Honda EU6500iS). Doing an equivalent study with Diesel results in about 2,000 hours at 50% load. The difference is almost irrelevant. I'm much more interested in fuel storage and availability.
    ChrisOlson wrote: »
    ... VERY sensitive to water ...

    Yea, I suppose that comes into play when you have to store the fuel.
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #113
    Re: Choosing a good generator

    That's a cool comparison method! If I apply that same methodology to our EM4000SX I can buy 1163 gallons of fuel for that $4000 (at today's prices). That fuel would give us 2643 hours @ 3 kVA output (what I measured in my fuel comsumption test on it doing real world battery charging). That equates to 7929 kWh or right on 50 cent/kWh. To put that in perspective, that's a little over 3x what grid power costs (at today's prices in town).
    --
    Chris
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  • 2manytoyz
    2manytoyz Solar Expert Posts: 373 ✭✭✭
    #114
    Re: Choosing a good generator
    Blackcherry04 wrote: »
    Most weekends during the summer I run a Honda EU2000 on my boat, My buddy has a Yamaha EF2000iS. One thing we noticed is that his is much louder under load with the ECO throttle on. I can run a IOTA 55 amp on the Honda and it's RPM stays a the lowest point and quiet. The Yamaha jumps up to a much higher RPM and is much louder using the same size charger. It's no big deal till your running them side by side at night. Just some Info about them.

    The Honda EU2000 is a quiet series inverter generator, rated at 59 dB at full load. The EF2000iS is rated at 61 dB at full load. The EF2400iS is 58 dB at full load. Every 3 dB is twice the sound energy.

    I can run a 5000 BTU A/C unit from mine at idle (53 dB).

    When shopping for generators, it's very important to read and understand the noise ratings. Some see "Honda" or "Yamaha" and assume they are quiet. Both companies also make contractor grade generators, and even just sell motors that third party companies slap their own power head on it.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #115
    Re: Choosing a good generator
    2manytoyz wrote: »
    The Honda EU2000 is a quiet series inverter generator, rated at 59 dB at full load. The EF2000iS is rated at 61 dB at full load. The EF2400iS is 58 dB at full load. Every 3 dB is twice the sound energy.

    I can run a 5000 BTU A/C unit from mine at idle (53 dB).

    When shopping for generators, it's very important to read and understand the noise ratings. Some see "Honda" or "Yamaha" and assume they are quiet. Both companies also make contractor grade generators, and even just sell motors that third party companies slap their own power head on it.
    The point I was making might have been missed. Lets say the Honda is at it's lowest ECO throttle position while pulling 5 AMPS, the Yamaha will speed up while pulling 5 AMPS making it louder, just a control sensitivity difference. Just a point if noise is a concern. Can't say that one is any better than the other. The Honda had to have a complete re-build with 5 hrs on it because of a bad rist pin problem. That happens with anything mass produced.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #116
    Re: Choosing a good generator

    And--Very roughly, 3 db difference is "noticeable" if you pay attention and 10 db is a night vs day difference (you probably could not hear the -10 db down genset in the presence of the louder unit).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #117
    Re: Choosing a good generator

    Sometimes the type of noise it makes is as much difference as a reading on a db meter too. An example is that the background noise in an urban environment can be as loud as a small generator, but a generator running will cause annoyance while the background noise doesn't.

    I don't know about the EU2000 but the EU3000 makes more apparent noise at full load than my EM4000SX does. The specs show the EU3000 at 58 db(A) at rated load, and the EM4000SX at 71 db(A). But the 4000SX has more of a deep throated growl intermixed with a slight turbine whistle type sound to it while the EU3000 has a tinny-sounding, annoying, hammering at full load. The 4000SX is much more pleasing to listen to, making it seem quieter, because of the more steady muffled-sounding type deeper noise, while the higher pitched hammering of the little engine in the EU3000 is just plain annoying after awhile.

    I attribute that to the fact that the little GX200 only develops 5.5 hp and it's operating at 85% of its max power output in the EU3000 at rated load of 2.8 kVA. The iGX270 in the 4000SX develops 8.8 hp (up from 8.5 in the old GX270), and is operating at 61% of its max rated output at 3.6 kVA. The harder a particular engine works, the more pronounced the "hammering" becomes on a single cylinder because of combustion noise and a sharper exhaust note.

    I think the turbine-type sound from the iGX comes from its re-designed cooling blower that only requires 50% of the hp to run that the old GX had. Looking at it reminds me of a compressor wheel in a turbocharger. It's got smaller fins on the outside where they travel the fastest, and bigger fins in the middle where the fins have a lower tip speed. It also has a huge air intake screen over the flywheel and doesn't have an exposed recoil like the GX had.
    --
    Chris
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #118
    Re: Choosing a good generator
    BB. wrote: »
    And--Very roughly, 3 db difference is "noticeable" if you pay attention and 10 db is a night vs day difference (you probably could not hear the -10 db down genset in the presence of the louder unit).

    Bill, a sound attenuated enclosure for a conventional portable can make a huge difference in how much noise it makes too. The one I built for our 4000SX cut its noise to about what the EcoGen used to make. And that was very quiet - approximately like standing by a large residential central AC unit running. In the enclosure, and with the method I used to route the exhaust thru the enclosure wall, along with sound deadening insulation in the enclosure, at full rated load it is approximately the same noise level as a EU3000 idling with no load on it.

    The generator is inline with our kitchen kitchen window over the sink, and about 10 feet away from the house. When the generator is running we can't hear it in the house with the window closed, standing right by the sink. The only way we know it's running is by the status lights on the remote for the inverter showing AC2 being lit up. And that's a "loud" (relatively) 71 db(A) rated portable.
    --
    Chris
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #119
    Re: Choosing a good generator

    Oh--I truly believe in quiet generators... I have a friend that was getting old hunk of iron 5kW genset running again for somebody else (I am sure it would run forever with just fuel and an oil change)--When he fired that puppy up--It was irritating two blocks away.

    Between irritating folks in the home and next door--I could not imagine running a loud generator during evening/over night in a residential area--even during an emergency (unless you start stringing extension cords to your neighbors' homes to keep them "happy").

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #120
    Re: Choosing a good generator

    Fire up my Lister without ear protection,, and prepare to hurt! One of my seasonal neighbors hated it from over a mile a way on a summer night.

    Chris, still interested in trading your water cooled Honda for it?

    Tony
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #121
    Re: Choosing a good generator

    Well Tony, it might be kind of a bad deal (for you) ;)

    I had to do some welding on a wind turbine transmission case yesterday. I tried that generator on the welder to see if it would work. It makes it pop right up out of its chair, stand at attention and recognize that's it's got something hooked up to it. But it runs my Lincoln AC/DC 225 amp spark welder with no problems, with the welder set at Full Dawg.

    So now I'm keeping it :p
    --
    Chris
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