winnehonda
Tequesta, Florida
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Joined: 03/21/2005
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F53 chassis. Has anyone noted a MPG difference when running generator air vs engine air?
Mark Hanlon
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Jerry_Keller
Southern California
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Joined: 08/02/2004
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Folklore has it that it's cheaper to run generator with a/c than engine a/c. If you read the generator manual, under moderate load, your generator will use less than 1 gallon per hour. The real issue is what is the impact to mpg of running the dash air.
Lots of discussion on this board.
Jerry Keller
2006 Bounder 35E, W22
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Polishnurse
Schodack, NY
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Joined: 03/13/2007
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Some say it also adds additional heat to the engine since the condenser is mounted in front of the Radiator. Loss of HP, and not as efficient as the roof top AC. Bill
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mpmeisch
Aurora, IL
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Joined: 05/17/2008
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If you are on flat land, and the people needing to be cooled are in the front seats than your best to go with the engine A/C, but if your in the hills or mountains and the people needing to be cooled are in the back then the coach A/C makes sense. You will get about .5 to 1.0 mpg better with the engine A/C than using the generator.
Flying for work, cruisin' for fun!
2001 Itasca Suncruiser
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Gale Hawkins
Murray, KY
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Joined: 07/22/2007
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mpmeisch wrote:If you are on flat land, and the people needing to be cooled are in the front seats than your best to go with the engine A/C, but if your in the hills or mountains and the people needing to be cooled are in the back then the coach A/C makes sense. You will get about .5 to 1.0 mpg better with the engine A/C than using the generator.
Well stated.
Also running the generator puts off more heat and is another fire risk when running down the road.
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zigzagrv
Nazareth, PA
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For me, COMFORT is the deciding factor. I use whichever makes me and the DW comfortable. Have also used both at the same time in very hot weather.
Ron
2003 Gulf Stream Ultra Supreme 33'
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DeweyClawson
Enon Valley, PA
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Pretty easy check:
Driving down the road, watch the Scan Gauge/VMSpc fuel flow and turn on the dash A/C. You can watch the mpg or gph. gph is easier as that is the fuel figures for the gen.
Every vehicle I have ever ran, from 30 ft boat - 36 ft MH to 200+ ft Boeing 767, running the on board gen was the most expensive way to power/produce elec.
BUT
If the gen is ALREADY running anyhow, then it is the MOST cost effective (read cheapest) way to produce elec/power that item.
WHY
The gen under light load - I think light load is a real estate term meaning at idle or not powering anything - burns about half gph - so that first half gallon is basicly wasted just to power the eng running the gen. Generally, going from no load to full load doubles the fuel flow. so the first half of the fuel flow is producing nothing but just keeps the eng running. That 400hp monster under the hood is already running, so it has a big advantage when a small load is added to it. If you had to run that monster while parked, just to run the A/C it would be terribly ineficient.
Waiting for some real numbers from a scan gauge.
JMHO
The fool learns from his own mistakes.
It is the wise man who learns from the mistakes of others.
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PeppyPilot
NW Chicago Suburbs
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No hard data here, except that we know that our 5.5 kw genny burns about 1/2 gal per hour running a/c (we can measure this pretty accurately when dry camping). We know that both sources burn some gas; I suspect which is more efficient may depend on circumstances. In my opinion, the cost difference is probably minimal, so it is not our deciding factor.
I like to run dash air every so often, just because mechanical things need to be run and exercised. I generally use if for shorter runs when the engine is not under a heavy load. Cooling is adequate for the two of us riding up front. I also use it when fuel drops anywhere near the genny cut-out point.
Longer runs, hotter temps, engine under heavy load (towing, hills, stop and go traffic, etc.) I go with the genny - which also gives me microwave, electric hot water, etc. Again, running the genny often is a good thing for it.
CJ, Pepe, Abby & Gretchen (in spirit)
2003 Itasca Suncruiser 33V
Workhorse W-20 chassis
2004 Jeep Liberty Limited w/Blue Ox
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George Beggs
Homosassa, FL.
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I need to run both to keep cool. I turn off the dash air when going up hills.
George & Linda
1999 Pinnacle F53 6.8L V10
Banks Transcommand
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driveby
Vancouver BC Canada
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I notice no mileage difference but then I don't track to the .5 gallon either - too many different driving areas (mountains/traffic etc) but I do notice that the useable power for acceleration and hills is vastly different. As well the kids are often at the dinette colouring. All that means is I tend to use the dash AC when I'm alone bringing the MH to and from storage and the genny/roof AC when underway.
2008 Itasca Sunova 35J Class A
1997 TJ Sahara, hard and soft tops and AC
Held together via Roadmaster Falcon 2 tow bar and stopped by US Gear Unified Brake system.
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