Generator year.

Guysakar wrote:


OK, that is what I was looking for. I am familiar with the Honda EU2000i, which reduces the RPM's under light load, etc...

You are saying that most motor home generators just run at a constant RPM regardless of load?

So what does that do for fuel consumption? I assume that motor home generators are nowhere comparable to portable generators, then.

I wonder why they can't use the same tech that is in the portable ones in a motor home.

So on a 4K watt Onan, you think 1/2 gallon an hour?

It might be more cost effective to just buy a portable gen and never even mess with the onboard gen, if doing a lot of dry camping.

A Honda 3000 (peak) 2800 (constant) watt gets .17 gallons an hour at 1/4 load and .47 at max load.

Unloaded, 0.3 gallons per hour. Half-load, 0.5 gallons an hour, full tilt, 0.7 gallons an hour. Source here.

As for inverter technology, most everyone on RV.net would agree with you. It would require some engineering though, because with most portable generators, you flip them off of Eco-Throttle (or a similar setting) before firing up the A/C or else the generator may not "catch" the load and spin up in time. Of course, this can be handled by a circuit similar to the Yamaha 3000iSEB and using the battery for a quick added wattage to handle the incoming locked rotor amps from a compressor (or on a lesser basis, a magnetron.) However, for a lot of things, the onboard Onan genset is "good enough". Since gasoline models tend to use the onboard fuel tank, they tend to have plenty of run time, which means it is a lot more convenient to just push a button inside the coach to get the generator running than to go outside in the cold, get out the gas container, manually start the generator or generator pairs, then head back inside to dry off, thaw out, or get cool.

Another use for the inboard genset is using it with a controller from Onan or Magnum Energy. You can then configure it to fire up the generator when the batteries get below a certain voltage, run for a few hours, then stop. You can also configure quiet hours so the generator will not fire up (unless manually actuated.)

My next rig, I'm doing the best of both worlds. The inboard genset will be what I use normally. However, I plan to take along a 2000 watt Honda which is more efficient at gas when boondocking. This provides not just better charging and allows use of all electrical items but the A/C (not all at once), but if the house batteries go flat, the Onan may not start, so it would provide a way to get the battery bank charged enough to allow the onboard genset to take over.

Hi All.

One way to help quite down a Built-ion Generator, is to use a Ven-Turi System on your Generator. They will quite it down by quite, and also carry the Carbon Monixide over and above the Motorhomes roof line on most Motorhomes.

Our Motorhome runs at 36000 rpm no matter what the load is. Its just the name orf the beast. But that Ven-turi Systems makes so we hardly hear it inside our Motorhome when it running.

Of coarse, if I want quitter, I can use our "Twin Hondas, EU2000i's", "Paralla Kit" with the "Extended Run Tank", then it will adjust to the load put on it. Our Hondas, we don't even notice them while running while we are in the Motorhome.

Good Luck. Happy Travels, Dan & Jill & our two "Yorkie Kids" who love to Travel as much as we do.

The quick answer on the generator is that NONE of the installed gas models of any year vary RPM, nor have inverters as one needs the other to work.

Guysakar wrote:

Hi, thanks for your reply. I wasn't talking about the state of the generator, but how the generator was designed.

Some of the older motor home generators ran at a constant rpm and did not cycle down when load was low, resulting in poor fuel consumption.

And some of the older ones are much louder than the newer ones.

As I said, everything including how quiet the generator operates will all be directly related back to how the unit has been maintained over the years. To my knowledge, no Onan built in generator runs at variable RPM's based on demand. I know our Onan 6500 watt generator in our 5'er runs at a constant 3600 RPM's regardless of the load.

Happy camping!!! See y'all down the road!!!:)

mlts22 wrote:
All inboard generators will run at either 1800 RPM (older, pressurized models with four poles), or 3600 RPM (newer gensets.) The only exception will be some diesel models that use an inverter.

Portable generators are a different story.

The key for the inboard generators is how it is installed. The Onans can be pretty quiet if the generator is shock mounted, acoustic insulation is used, pipes are vibration dampened, and an exhaust resonator is used.

As for MPG, I'd say 8-12 with a Ford E-350/E-450, 12-17 with a Sprinter chassis.

OK, that is what I was looking for. I am familiar with the Honda EU2000i, which reduces the RPM's under light load, etc...

You are saying that most motor home generators just run at a constant RPM regardless of load?

So what does that do for fuel consumption? I assume that motor home generators are nowhere comparable to portable generators, then.

I wonder why they can't use the same tech that is in the portable ones in a motor home.

So on a 4K watt Onan, you think 1/2 gallon an hour?

It might be more cost effective to just buy a portable gen and never even mess with the onboard gen, if doing a lot of dry camping.

A Honda 3000 (peak) 2800 (constant) watt gets .17 gallons an hour at 1/4 load and .47 at max load.

It's extremely rare on even a new MH to find a generator that doesn't run at a constant RPM, their all either 1,800 or 3,600. Some of the very newest most expensive units have diesels that will vary their speed because they work in conjunction with an inverter.
With your price range of $15K you won't be buying a unit with one of those I'm sure.

crickeydog wrote:

Guysakar wrote:
1. Do you think that that is going to be a problem with 2000 models? One in particular that I am looking at has a 4K watt Onan, but the owner is an elderly couple and doesn't know much about it. 2. What kind of MPG can I expect from a Class C 22-25 footer, with a slide?

1. That question can only be answered by knowing the complete maintenance history of the generator. From your statement, "the owner is an elderly couple and doesn't know much about it", I'd say you're probably looking at a generator that has not been properly maintained. That'll cost and I'd bet it'll cost you dearly to get the generator up and running properly. The only way to know what you have in the way of the generator is to have it surveyed by a factory trained Onan repair facility.

2. "What kind of MPG can I expect"? In a word...bad. But nobody buys an RV for the great fuel mileage. Again, a lot will depend on how the engine has been maintained. You may have a gem, then again you may have a lump of coal. In great running condition you can expect 6 to 10 MPG depending. Again, the only way you'll know for sure what you have under the hood is to have the engine, drive train and entire chassis surveyed by a certified mechanic for the particular chassis you have under the hood.

Good luck.

Happy camping!!! See y'all down the road!!!:)

Hi, thanks for your reply. I wasn't talking about the state of the generator, but how the generator was designed.

Some of the older motor home generators ran at a constant rpm and did not cycle down when load was low, resulting in poor fuel consumption.

And some of the older ones are much louder than the newer ones.

All inboard generators will run at either 1800 RPM (older, pressurized models with four poles), or 3600 RPM (newer gensets.) The only exception will be some diesel models that use an inverter.

Portable generators are a different story.

The key for the inboard generators is how it is installed. The Onans can be pretty quiet if the generator is shock mounted, acoustic insulation is used, pipes are vibration dampened, and an exhaust resonator is used.

As for MPG, I'd say expect 8-10 with a Ford E-350/E-450, 12-17 with a Sprinter chassis.

Most Onan generators from that timeframe if it is a model designed for use in an RV will be quiet. My definition of quiet is if you can barely hear the generator running when you are 20 feet away it's quiet. If you are inside of the RV you barely hear the generator, you may feel a very slight vibration but only hear a muffled rumble when it's running. That's what I consider quiet.

Any RVer whether they have a motorhome, van or vehicle towing a TT or 5th wheel can expect 6 to 12 MPG. Most will fall in the 10 MPG range at best.

Also since you are looking for an RV, keep in mind most RVers start off thinking they need a small RV. However the statistics show the typical RVer over the course of their RV life will end up with larger RVs. Ususlly will go through 3 RVS until they get one big enough to truly meet their needs. The normal course is to start off with a truck camper or 15-20 foot travel trailer then move up to a 25 to 30 foot TT, MH or 5th wheel... then land on a 35 to 40 foot MH or 5th Wheel/ TH.

Guysakar wrote:
1. Do you think that that is going to be a problem with 2000 models? One in particular that I am looking at has a 4K watt Onan, but the owner is an elderly couple and doesn't know much about it. 2. What kind of MPG can I expect from a Class C 22-25 footer, with a slide?

1. That question can only be answered by knowing the complete documented maintenance history of the generator. From your statement, "the owner is an elderly couple and doesn't know much about it", I'd say you're probably looking at a generator that has not been properly maintained. That'll cost and I'd bet it'll cost you dearly to get the generator up and running properly. The only way to know what you have in the way of the generator is to have it surveyed by a factory trained Onan repair facility. Be prepared for some expensive bad news.

2. "What kind of MPG can I expect"? In a word...bad. But nobody buys an RV for the great fuel mileage. Again, a lot will depend on how the engine has been maintained. You may have a gem, then again you may have a lump of coal. In great running condition you can expect 6 to 10 MPG depending. Again, the only way you'll know for sure what you have under the hood is to have the engine, drive train and entire chassis surveyed by a certified mechanic for the particular chassis you have under the hood. Be prepared for some expensive bad news.

Good luck.

Happy camping!!! See y'all down the road!!!:)