Running AC while driving

[MNawman]

Hey guys, I have a 2014 Entegra Aspire and was wondering if I can run one of the roof AC units while I'm driving without the gen set. It would be solely on the inverter and or alternator. I looked thru my owners manual, but couldn't find anything on it. Thanks for any assistance.

[wa8yxm]

MNawman wrote:
Hey guys, I have a 2014 Entegra Aspire and was wondering if I can run one of the roof AC units while I'm driving without the gen set. It would be solely on the inverter and or alternator. I looked thru my owners manual, but couldn't find anything on it. Thanks for any assistance.

Short answer NO:

Long answer:

Let's assume you have a 200 amp alternator (That's a big sucker, most are smaller) that, is roughly 2,000 watts, My roof air's draw 13.5 amps at 120 volts that's 1620 watts, This leaves you less than 400 watts to run dash air, ignition, lights, turn signals, engine control computer, and so on.. Add to that the fact that alternators are NOT designed to put out full power full time and the alternator will swiftly fail. This would be a very expensive alternative.

That said.. I know folks who do it, but they have upgraded the alternator seriously.

Better to use Mr' Onan's contribution to your comfort. Plus, you really should run said Generator 1/2 hour (or more) under 1/2 (or more) load every month.. This is a good time to do it.

Side note:

Doing 55 down the freeway, Generator powers A/C nicely and no problems
Doing 0.00 (parked) I had a problem with the CO alarm doing it's thing (Alarming) after 2 hours of generator run time.

Added Gen-turi (I stow it when doing 55, actually anything more than 5.5) I have run over 24 hours on occasion with no alarm.. I see people yammer things like "But with the Gen-turi this bad or that bad thign can happen" fact is.. it can not, impossible is the word that applies.. One such example: YOur exhaust fans can suck in fumes from up by the roof.. .. Now think about this folks EXHAUST blows OUT.

And the fumes they warn about are released ABOVE the roof, and the nature of warm (not hot) exhaust gasses is they continue to go UP UP AND AWAY, not down and into your rig.. It's that up up and into the rig they used to go before the Gen-Turi took them up to where the problem is no more.

[J-Rooster]

I turn on the genset and run the A/C whenever it gets above 85*

[OhhWell]

msmith1199 wrote:
Just out of curiosity, what do regular buses do to keep air conditioning flowing throughout the bus? I've been on some real nice tour buses that keep nice cool air flowing throughout the bus somehow run just off the bus engine. Are the bus conversion motorhomes able to do the same, or are they running different types of AC's?

That is a very good question. I've seen some busses that have a massive mechanical AC compressor on the massive diesel engine. That makes sense but I have also seen some busses with a large shroud on the top of the bus and when inside, it would appear that the shroud contains a self contained AC system. I did find that they make 24v DC powered rooftop AC units for busses but the couple I found were smaller and mostly for the driver. Maybe someone makes even larger ones and the coach manufacturers add a massive or secondary alternator on the huge bus engine.

[dougrainer]

msmith1199 wrote:
Just out of curiosity, what do regular buses do to keep air conditioning flowing throughout the bus? I've been on some real nice tour buses that keep nice cool air flowing throughout the bus somehow run just off the bus engine. Are the bus conversion motorhomes able to do the same, or are they running different types of AC's?

Most, even the RV type Prevost have 24 volt systems and 24 volt Inverters. Which can power the AC units. Doug

[Effy]

Impact to MPG is nominal considering you are driving an apartment. The gen is there for a reason, to provide power when not connected to shore power. Run it, they like to be run. Your dash AC will sruggle to cool anything but the first 4 feet of the coach. Then gen and AC are more efficient at cooling the entire MH - hence why you have them. You and those you travel with will thank you and your coach will take less time - no time actually - to cool down once you arrive. I love to read posts about people that put up shower curtains and all sorts of things to cool a 6x6 area. How much do you save - if any - and why did you buy a MH with a gen and central air? I mean what's the point? I run the gen in ours about 90% of the time we are travelling. I don't boondock so it's a good time to excercise it. Kid can watch TV, we can use the microwave, central air, outlets and I don't use LP for the fridge. I don't hear it and I haven't noticed any real impact to mpg. Or at least anything to trade the comfort and convenience of having power. I mean that's one of the reasons I bought a MH. SO we could travel in comfort.

[bigwheelsturnin]

we just run the generator...using the front AC...closing the door to the back...u hope to not be travelin in any kind of heat like that 112° we had couple of summers ago.

[Heisenberg]

Your generator needs to be used. They tend to be more reliable with more use. Cheap maintenance when you consider the comfort. It will also remove AC and Alternator load from your engine. I have not seen much change in my MPGs. 7ish MPG is 7ish MPG.

[msmith1199]

Just out of curiosity, what do regular buses do to keep air conditioning flowing throughout the bus? I've been on some real nice tour buses that keep nice cool air flowing throughout the bus somehow run just off the bus engine. Are the bus conversion motorhomes able to do the same, or are they running different types of AC's?

[Nomadac]

IMO if you can afford the MH then you can afford to run the generator while traveling. I run mine whenever the temps are above 80 outside.

[gsander1]

Bill.Satellite wrote:
At a gallon per hour to run the generator and traveling at 60 MPH that would have you are burning 1 gallon every 60 miles. Fuel mileage is reduced by 1/60 of a gallon per mile. .017 MPG reduction.
Long winded response short? Run the generator.

Not correct Bill. Real world example.

Running at 56 miles per hour @ 8 miles per gallon burns 7 gallons
Consume an additional gallon you burn 8 so you get 7 miles per gallon.

Result is a reduction in fuel economy(in this example) of 12.5%

[Bill_Satellite]

At a gallon per hour to run the generator and traveling at 60 MPH that would have you are burning 1 gallon every 60 miles. Fuel mileage is reduced by 1/60 of a gallon per mile. .017 MPG reduction.
Long winded response short? Run the generator.

[dougrainer]

There is NO free power. If you connected the Inverter to run the Roof AC (you can), the engine Alternator will supply the current needed. BUT, there is NO free power. The heavy load and wear and tear on the Inverter and Alternator will bypass the low fuel consumption on the genset. Besides that, this will give you a chance to run the APU. A LOT of APU's are hardly run and lack of use causes problems on APU's. Doug

[rgatijnet1]

Golden_HVAC wrote:
Hi,

I know someone who does run one A/C through his 24 volt Trace 4,000 watt pure sine wave inverter via his 100 amp 24 volt alternator. The bus also has a 200 amp 12 volt alternator, and he does not overload either. However it does put stress on a 12 volt alternator and it's belt to run it at maximum amperage for hours on end.

I would not suggest it, however with the right alternator and upgraded belts it is possible. You must be using the pure sine wave inverter, because the compressor is a high torque motor, and can not run on modified sine wave power.



Fred.

The extra HP required to run the alternator(s) causes his fuel consumption to increase. Whether or not that increase is more than running the generator is hard to tell. There are no free rides so power consumed means that power has to be generated somewhere. To generate that power is going to use fuel with the main engine or a separate generator.

[Golden_HVAC]

Hi,

I know someone who does run one A/C through his 24 volt Trace 4,000 watt pure sine wave inverter via his 100 amp 24 volt alternator. The bus also has a 200 amp 12 volt alternator, and he does not overload either. However it does put stress on a 12 volt alternator and it's belt to run it at maximum amperage for hours on end.

I would not suggest it, however with the right alternator and upgraded belts it is possible. You must be using the pure sine wave inverter, because the compressor is a high torque motor, and can not run on modified sine wave power.



Fred.