Generator Use While Driving

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Well-known member
Feb 15, 2006
San Diego
Under what circumstance should I use my generator while I am driving my '98 Class A?  During my walk through, the service guy told me to use my generator while driving if my two rooftop Airconditioning units were in use.  Is there any other reason to use the generator while driving?  Doesn't the engine generate AC (alternating current)  power?  I am leaving for a long trip on Sunday and would like to figure this out.  Thanks for your help.


The alternator on your engine will only provide you with 12V. So, unless you have an inverter, the only way to run any 110V appliances while underway is to run the generator. If the dash air doesn't cool the coach sufficiently, then running the roof air with the generator running is the way to go.

If you have small 110V items that need to be powered while underway, you might consider buying one or more small inexpensive (relatively) inverters that plug into a 12V receptacle.
You will need the generator to run the roof A/C units, one or both, while travelling. ?The engine does not produce any usable AC power.
Depending on your rig there may be several reasons to have AC-Power (not Air Conditioning) on while driving

For example... In my coach there is a Dish-Pro Dual DVR and a Motosat T2-Automotion antenna (on roof) so that television shows can record while I'm moving from place to place (can't watch and drive at the same time, though I've seen people who tried...... And I've seen their cars... I worked 25 years as a police dispatcher and 3 more as a tow truck dispatcher.... Get the picture)

These devices only have 120 volt cords, no 12 volt

I can, if someone else is driving, retire to the back room and watch in motion tv

I have other 120 volt hardware in the rig as well

All this stuff takes 120 volts, and I prefer not to shut it down when driving.

I also have an Xantrex Prosine 2.0 inverter/charger, this takes the 12volts the vehicle engine's alternator puts out, and converts it to 120 volts so I don't need to run the generator 24x7 if parked where there is no ac, or if going down the road.

There are other reasons to use the generator as well, but keeping 120 volt stuff powered is #1

And my dash air is out of service so I need those rooftop units
Thanks for the feedback everyone!  As usual, you are a great help.  After a quick inventory of all the  electrical "gadgets, gizmos, bells. and whistles" in my rig, it turns out that, well, I have none  :'(.  Looks like I will only use the generator when running  the A/C units.  Otherwise, my son will use one of the small portable inverters for the TV.  The more I use these systems, the more I will grasp what runs what, off of what source.

It's very much appreciated when someone asks a question, receives answers, then comes back with feedback like yours. It lets us know that someone actually read the answers and did something with them. Thank you!
Hi Jozze,

When ever we are going somewhere in our motor home, the generator is usually started before the coach engine is started. I would say that it runs 90%+ of the time when the coach is underway. It takes less fuel to run the generator and the AC that it does to run the engine and dash AC, plus the roof AC does a better job than the dash unit.

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