Driving with the generator on

[sato4000]

Just curious if anyone knows the difference in MPG when riding with and without the generator on. Has anyone done any measurements on the gas mileage they get?

Thanks

[pnichols]

FWIW, my RV's cooktop has always taken a few minutes to get going after having had the propane turned OFF at the tank. I've had the propane system leak checked and it holds pressure for a long period just fine.

Something else is causing too much air and not enough propane remaining in the line between the propane tank and the cooktop after having the tank turned OFF for awhile.

Hence, we have left the propane tank valve ON all the time since buying the motorhome in 2006 (except when on a ferry with it) ... this includes when gassing up. When gassing up I turn OFF the coach's battery bank interconnect switch so the refrigerator or water heater can't automatically light up when refueling.

[JaxDad]

pnichols wrote:
The cooktop takes a bit of waiting and lighting attempts to get it going after the tank valve has been OFF for awhile and then turned back ON.

You do realize that if everything is turned off, and the gas is escaping, you have, no matter how small, a leak in your propane system, right?


You should be able to turn off the tank valve for 6 months and have no such issue relighting an appliance.

[Paoli]

Capt.Storm wrote:
Mine is always on except when they fill it they always turn it off.

When you go on a ferry they require you to turn it off.
I know they check it when going on a BC ferry.
They taped my propane access door.

[Capt_Storm]

Mine is always on except when they fill it they always turn it off.

[pnichols]

maillemaker wrote:
I would suggest turning it off when not using it. There is no reason for it to be on ...

There's a couple of reasons we leave it ON:

- The tank valve seat seem just a bit "soft" or "fragile", as if the valve is not all that rugged and intended for a lot of turn-ons/turn-offs over it's lifetime, we thought best to leave the valve alone as much as possible. If may not be designed for a lot of usage cycles.

- The cooktop takes a bit of waiting and lighting attempts to get it going after the tank valve has been OFF for awhile and then turned back ON.

[maillemaker]

in fact the propane tank is ON all the time, even when in the backyard at home.

I would suggest turning it off when not using it. There is no reason for it to be on and if you develop a leak and your RV fills with propane you may have quite a surprise on your hands.

Steve

[fortytwo]

I have yet to see a factual presentation of the amount, if any, gas mileage is reduced by using the cab a/c. My V-10's (3 different ones) have always had so much extra power available at cruise that I think it will be difficult to measure.

If you have a scan gauge you may be able to get an indication on a long flat stretch of highway by watching the engine "lod" reading as you switch the a/c on and off.

If the outside temp is really high, and/or you have passengers in the coach then run the generator and house a/c. That's one of the reasons you have a generator.

I've been reading RV mags starting with Camper Coachman in the 60's (when the biggest propane issue was folks dying from using clay flower pots over the stove burner to stay warm while sleeping) and continuing with Motor Home and FMCA today, plus have followed several RV forums since the coming of the net. While the wisdom of using propane while under way has been debated the 50 years I've been following the issue, I don't recall reading of a SINGLE documented case of a traffic incident caused by propane use in a reefer. All modern propane systems have an auto-shutoff if propane goes to full flow. Failure to turn off propane devices while refueling has had documented bad results. My propane has been on while moving for 50 years.

However --- follow your comfort level. RVing is not about anxiety attacks.

[pnichols]

maillemaker wrote:
The Norcold in my old 1990 Winnebago Warrior is only AC or LP, though it needs 12V to operate on LP.

The Norcold in my 2005 Itasca operates the same. The same warning is on the back of my visor. I never realized the warning was there until the poster above mentioned it!

The DW would NOT tolerate the refrigerator being OFF when going down the road - so we of course leave the propane tank valve turned ON when traveling - in fact the propane tank is ON all the time, even when in the backyard at home.

I really like the concept of the 3-way RV refrigerators and I wish our Norcold was that. There is one other way to keep these type of refrigerators running when under way. Use a small inverter to power the RV's 120V AC system while on the road. A 400W inverter should be large enough. "Most" engine alternators would be able to keep up with this amount of current draw so as to power the refrigerator while still keeping the coach batteries fully charged.

[maillemaker]

Can you provide any documentary support for your assertion? A significant portion of RVs only have AC/LP fridges. The are designed to operate on LP while being driven.

The Norcold in my old 1990 Winnebago Warrior is only AC or LP, though it needs 12V to operate on LP.

However, my owner's manual and the instruction sticker stuck on the back of the driver's sun visor says to turn the propane off while underway.

So they must intend you to run the generator to operate the refrigerator while underway.

I use propane.

Steve

[Capt_Storm]

Well you can also use the 12v for the fridge dry camping so I don't necessarily think the 12v is there for just going down the road . That said mines on going down the road all the time. I shut it down to get gas though.

[Capt_Storm]

Well you can also use the 12v for the fridge dry camping so I don't necessarily think the 12v is there for just going down the road . That said mines on going down the road all the time. I shut it down to get gas though.

[Harvard]

JaxDad wrote:
I don't know about the insurance part of it, but in several Canadian Provinces it's illegal to go down the road with open propane cylinders unless it is the fuel source for the vehicles engine.

I suspect if it's illegal then the insurance company would deny coverage purely on that basis even if you're not from there.

I think that may apply to propane bottles but not frame mounted tanks.

Q: Do any trailers NOT have 3 way fridges where you would use 12VDC to run the fridge in transit? (meaning, they should have their portable bottles OFF)

[JaxDad]

tatest wrote:
Don't even think of it as difference in MPG, rather as 0.5 GPH (A/C is roughly 1/2 load) or about $2 per hour to have the house cool.

I guess it depends on what m/h you have, the dash a/c in my E-350 chassis will keep the entire coach pleasantly cool at highway speeds regardless of the outside temps I drive through.

I can't even measure the loss in mileage.

[tatest]

Don't even think of it as difference in MPG, rather as 0.5 GPH (A/C is roughly 1/2 load) or about $2 per hour to have the house cool.

Impact on MPG depends too much on all the other things that impact MPG, e.g. wind drag and travel speed. Running A/C drops MPG a lot more at 30 mph than it does at 70 mph, and sitting in a parking lot you are getting 0 miles per gallon while still burning 1/2 gallon per hour.