OT: Questions about RV A/C units

I think you should figure on 30 amps. You can't run any A/C at all on

15 amps without blowing something. Most RV generators don't put out enough to operate the A/C, judging from the RV that was parked in my driveway for awhile, and I even had to run a 30A circuit for it. There was a specific note about not trying to run the A/C on the generator (which had a 15A circuit breaker anyway.)

Virtually all RV generators will power the RV's A/C.

WRT your brother's "breathing machine, I assume you mean a CPAP machine for sleep apnea. Most CPAP machines will also run of 12 volts...

If you want to discuss this in greater detail, e-mail me at: jmfoster711@sbcglobal(REMOVE).net

3 KW is probably marginal, depending on the trailer. Air conditioners are one of the most difficult loads you can put on a generator. The startup current on the compressor is much higher than the run current, and it kills the generator. I have seen rules of thumb of air conditioners drawing three times the run current for startup. I had a pickup camper RV, I remember measuring 8 amps continous current from the air conditioner, so that would be around 25 amps start-up current, about what you might get out of a 3 KW generator on a good day if everything was working just right. But a 24 foot trailer could have a bigger air conditioner.

Richard

Bob Chilcoat wrote:

Hummmm Ill have to check my wifes.

Gunner

"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosphy of sniveling brats." -- P.J. O'Rourke

Don't guess about the power you will need. Take the nameplate ratings of all the components you will need to run, calculate the starting loads from the tables in the electrical code. Your gen will have to be able to start up that total load and maintain the running load. Don't put your brother at risk with an equipment failure out in the woods. Bugs.

My 7.5 kw generator in the 37 ft MH will run both AC units (and everything else) at the same time. When hooked up to 30 amp electrical service, only one can be run (along with the refrigerator,lamps, etc.). These are 13,500 BTU units. A lot will depend on the total load you have and the real world capability of your generator, but my guess is that you may be stretching things a bit thin.

But there's also a stagger-start arrangement of some sort with delay timers. It will give a delay to let the generator come up to full speed, start one AC unit, and 15 seconds later the other.

Try flipping both air conditioner compressors on at the same moment, and you'll stall the generator with the inrush current. (Seen it.)

-->--

In addition to what others have said, There is a 24 hour generator section at camp scholler. its a bit further from the gates than the handicap section, but at least you can run the gen.

John

I think there's a *huge* interest in alternative power sources on rcm - based on the previous threads that have run here in the past few years.

Many of them started right around the time when the country had that large blackout several years ago.

RCM type folks are always interested in either a) buying b) repairing, c) building from scratch or d) hooking up some kind of electrical/gasoline/sparks/fumes type device.

Jim

A lot will depend upon the A/C: is it a 13.5K BTU or a 15K BTU unit? (A

13.5K uses less power.) Is it a (relatively) new unit with a high Energy Efficiency or an older unit?

A 3KW "should" be able to power a single unit of either type BUT the real question is whether or not it'll be adequate for BOTH the A/C and the "breathing machine" at the same time.

Running full out your genset should be producing ~25 Amps - sufficient for an A/C and most RV appliances - and will be (as stated by others) a fuel hog.

You might also like to post this question on rec.outdoors.rv-travel or alt.rv.

I actually heard the following conversation (paraphrased) today at the service counter of Camping World ......

Guy comes in, and wants to upgrade his ACs so that he can run two at the same time. He is interested in two newer units that draw less electricity.

Counter man tells him no such animal exists, and that

Important part follows:

ACs draw about 15 amps with just fan running. During compressor startup, they can draw up to 30amps. Two ACs will not work on a 30A service, but require a 50amp service. Even if you have your own factory installed genset, some motorhomes and trailers will not run both ACs on one generator. I have a friend that has a Mallard that is like that.

Higher SEER rating has nothing to do with the amp draw during start up and during compressor kick in.

Steve

"Mark Morissette" wrote

About half, in my experience.

Also, do not try to run an AC on a power inverter. They will require a unit about 3 times the number on the sticker, and then, not run it well, unless it is a true sine wave converter, which is much more expensive. DAMHIK.

Watts is a direct current power term. Volt-Amps is used to describe alternating current power.

That's funny, nearly all the AC powered items I own list power used in watts. P=IE eh, I know, power factor and all that fits in there also.

Not exclusively though.

Jim

Yeah, what do they know. All of the voltage inverters I have seen also list output in watts, also. Amazing how little all of the manufacturers know! ;-)