Driving with the generator on

I would go with running the genset ONLY if it is the inverter type wherein the engine can idle when/as the A/C compressor cycles off.

Non-inverter gensets MUST run at full RPM constantly.

Yes its a comfort thing to run the roof air from the generator. I can not see how it would save fuel cost.

Couple instances where I run mine: When people are in the back. Or when the interior is very hot and the two air conditioners would cool it faster.

But generally when underway my dash air keeps the front cab area cool on very low fan speeds and lot of compressor off time.

darsben wrote:
All in all I feel the economic part is close to a wash but the convenience and comfort level is much greater.

A typical dash air system takes maybe (on average overall) 2hp, on an engine making 200hp, that is a 1% increase in load, therefore an increase in fuel consumption of 1%.

At 8.5mpg and 55mph that equates to 6.47 gal. / hour. A generator burning 0.5 gal. / hour would then be an increase of 7.7% in fuel consumption.

That's the equivalent of your mileage dropping from 8.5mpg to 7.9mpg.

I'd hardly call that "a wash".

JaxDad wrote:

darsben wrote:
Besides the greater fuel economy by NOT running the dash air you get the added savings on propane as your fridge will be running on electric.
So your rig engine temp will be less specially good thing on really hot days. Your engine a/c compressor will not be loading your rigs engine decreasing mileage.
Your fridge will not be using Propane.
Your microwave will be available for heating things

All in all I feel the economic part is close to a wash but the convenience and comfort level is much greater.

I'd like to see the science behind that idea.

A typical (large) automotive A/C compressor at maximum load uses about 4 or 5 horsepower. Now bear in mind that's ONLY when the compressor is cycling, which is FAR from being all the time.

If you look at the ratio of that load to what pushing the coach down the highway takes, I'd be surprised if you could even measure the loss.

There's lots of studies out there that show in a car or pickup, the increased wind resistance of having the windows open is actually greater than the loss by running the A/C

An idea or feeling does not necessarily have science behind it however I know I am damn comfortable doing it my way. If I want fuel economy I will buy a Prius not a motor home. So I stand by my statement that " All in all I feel the economic part is close to a wash but the convenience and comfort level is much greater."

darsben wrote:
Besides the greater fuel economy by NOT running the dash air you get the added savings on propane as your fridge will be running on electric.
So your rig engine temp will be less specially good thing on really hot days. Your engine a/c compressor will not be loading your rigs engine decreasing mileage.
Your fridge will not be using Propane.
Your microwave will be available for heating things

All in all I feel the economic part is close to a wash but the convenience and comfort level is much greater.

I'd like to see the science behind that idea.

A typical (large) automotive A/C compressor at maximum load uses about 4 or 5 horsepower. Now bear in mind that's ONLY when the compressor is cycling, which is FAR from being all the time.

If you look at the ratio of that load to what pushing the coach down the highway takes, I'd be surprised if you could even measure the loss.

There's lots of studies out there that show in a car or pickup, the increased wind resistance of having the windows open is actually greater than the loss by running the A/C

Our dealer told us the generator uses about half a gallon at 50% load.

-Michael

I thought it was closer to half gallon per hour. Anyone else go by this assumption?

How is less than 1 gallon per hour $4 at $3.75 a gallon??? Another post said .7 gallons per hour which is $2.65 per hour...much closer to 2 than double $2 per hour.

Besides the greater fuel economy by NOT running the dash air you get the added savings on propane as your fridge will be running on electric.
So your rig engine temp will be less specially good thing on really hot days. Your engine a/c compressor will not be loading your rigs engine decreasing mileage.
Your fridge will not be using Propane.
Your microwave will be available for heating things

All in all I feel the economic part is close to a wash but the convenience and comfort level is much greater.

Golden_HVAC wrote:
The generator will use about or less than 1 gallon per hour.

So what if it costs another $2 per hour to drive the RV?

Fred.

I think there's a typo in there.

At ~$3.75/gallon "about or less than 1 gallon per hour" would be about double "$2 per hour".