7KW powertech

[John316]

I also find that statement interesting about trying to run your genny as close to max as possible.

For example, we have a 20KW EPS (Kubota engine, Marathon head). If we are charging, and running four or five airs, we want every bit of that 20KW (even though we aren't maxing it out).

I find it interesting looking at the manufactures fuel specs for that generator. When running the generator at very little load, it takes a very small amount of fuel. An example of that is, I have some friends down in Hondurus that have a genset three years older then ours, but identical. They built an orphanage out there, and used the genset for power. They ran it for 12 hours, with little load (drill chargers and lights) and they used less then five gallons of diesel. However, load that genset down, and the consumption goes way up.

I am no expert on fuel consumption, but I think it could be similar to a V6 in a car compared to a V4 in the same car. The V6, in my experience, often gets as good or better fuel milage on the highway then the V4 (especially on hills).

Once again, I am no expert in these areas. I am just a simple master electrician that generally buys bigger.

FWIW

God bless,

John

[Zeroclearance]

I can agree with Sean..   I have a 20KW Powertech.  The fuel burn makes you sick.   Reading threads from Clifford with diesel at $4.00 a gallon has made me consider going to DC...

I have finally pulled the trigger an a new engine to drive my alternators.    Infact I have to change my alternator selection..   The reported burn rate will be a PINT an hour.   With my 50DN on the Series 60 I can run the new engine as a supplement power system.

While many have mentioned the purchase of A/C generators,   Inverted DC power is a good option IF you have the engine alternator.   

I'll keep the large Genset for backup.

[James77MCI8]

The reference to poles was not in regards to an inverter generator. I completely understand the operation and configurations of generators. Since most conversions are single phase 240/120 operations the implied comments were in regards to that. I like the 4 pole 1800 RPM configuration because they are quieter than the higher RPM units and there is less wear and tear on the mechanical parts of the set.

[niles500]

Just a reminder - when discussing sound pressure (spl) or db levels you must remember that 70 db at 50Hz is a different animal at 5000 Hz - HTH

[Sean]

For example, we have a 20KW EPS (Kubota engine, Marathon head). If we are charging, and running four or five airs, we want every bit of that 20KW (even though we aren't maxing it out).

Just for reference, five airs and a charger would be about 12.5kW.  If you don't have a load-adjusting charger such as is built into most modern RV inverter/chargers, then you would need somewhat more than this to carry the starting loads.

... I have some friends down in Hondurus that have a genset three years older then ours, but identical. .... They ran it for 12 hours, with little load (drill chargers and lights) and they used less then five gallons of diesel.

Sure, but you ought to be able to run that much load on perhaps half a gallon to a gallon of diesel, not just under five gallons.

I am no expert on fuel consumption, but I think it could be similar to a V6 in a car compared to a V4 in the same car. The V6, in my experience, often gets as good or better fuel milage on the highway then the V4 (especially on hills).  ...

That's not really a good comparison.  "Average" fuel mileage in a car typically involves using less than a quarter of the engine's horsepower.  Automotive engine designers work hard to get the efficiency curves to work with those numbers.  There is also naturally going to be a much smaller difference in fuel consumption between using 20hp out of 200 vs 20hp out of 300, in contrast to the difference between using 10kW out of 10 vs. 10kW out of 20.

The reference to poles was not in regards to an inverter generator. I completely understand the operation and configurations of generators. Since most conversions are single phase 240/120 operations the implied comments were in regards to that. I like the 4 pole 1800 RPM configuration because they are quieter than the higher RPM units and there is less wear and tear on the mechanical parts of the set.

Jim, I knew you knew all that.  However there will probably be people reading this thread, if not now then some time in the future, who do not.  I find it is best to be explicit about the details so that people who do not have your experience can understand what is being said.

-Sean
http://OurOdyssey.BlogSpot.com

[robertglines1]

Ok . $4000 a good price for that # of hrs. It does run constant 1800 rpm. It's in cabinet and not all that loud. (is within my tolerance level) it is water cooled. should run repair free until time for head bearings around 2,000hrs (200 hrs now). actually sounds to me like it is hardly broken in. Thanks Bob

[John316]

Sean, thanks for explaining that to me. I appreciate it. Makes sense what you said about the car engine sizes. However, I would be surprised if those folks down in Hondures could get much better fuel economy, even with a smaller set. It wasn't like they weren't running anything. Not to mention, I know a guy who has a 5.5KW gas burner, and he wouldn't be able to hardly run the thing for 12 hours with that much fuel....just saying...

If I get a chance, at some point, I will have to do a post on how we cool our generator. Everything is through the floor, with the radiator out on the front side. Even on hot days, we always run cool now. I will have to post more later on how we did it.

As far as size goes, I still don't regret getting the big one. And at full load we are running a tad more then 13K

God bless,

John

[FloridaCliff]

Ok . $4000 a good price for that # of hrs. It does run constant 1800 rpm. It's in cabinet and not all that loud. (is within my tolerance level) it is water cooled. should run repair free until time for head bearings around 2,000hrs (200 hrs now). actually sounds to me like it is hardly broken in. Thanks Bob

Bob,

As a point of reference, I paid 3500 for a 8kw with 400 hours.

Is it still under any kind of warranty?

At 4000.00 you are right in the ball park, IMHO.

What model?

Cliff

[rv_safetyman]

I have made this observation in other similar threads.  Noise really has two issues.  The first is sound pressure level.  We measure that in db.  The second is sound "quality".  Both are extremely important.  For example, scraping your fingernails on a chalk board will produce rather low sound pressure levels but it will drive you crazy.  I have grandkids that can make noises that really gets on my nerves, but has low sound pressure levels (after I tell them "inside voice" ).

The reason I bring this up is that a constant sound is not nearly as obnoxious to me as an engine that is constantly changing RPM.  I have been at non-bus rallies where several motorhomes have the new inverter generators and I just go crazy (crazier?).  I find these generators to be terribly obnoxious even though the sound pressure level is not all that bad.

Sensitive hearing can be a terrible thing

Jim

[buswarrior]

I have one of those lovely 3K Yamaha gas inverter generators.

As noted by Jim, I turn the throttle control off so it runs steady, and the Trace 4024 and the Yamaha seem to get along much more smoothly as well.

The Trace and the Yamaha can run two mid 1980's roof airs for as long as I tried it out, with an amp or two to the good, FWIW.

happy coaching!
buswarrior