Air Conditioners and Generators

[horton333]

So I just got my first generator: $175 for an old 2kw no-name (PowerTek) inverter on Kijiji.
I have seen many posts about what capacity of generator is required to run an air conditioner, all saying it cannot be done with a 2 kw unit. This makes total sense, the surge is way beyond the surge rating (on mine it is only 2.2kw surge) and an inverter based generator should be very sensitive to an overload.
Being inquisitive I decided to try to see if the A/C would work on the low setting, mine has three. It did. Turns out it works even on the highest setting (13,500 BTU unit). I even left it running long enough to cycle on/off a couple of time to see if I was just 'lucky' on the first surge. Kept lasting cool air like I was on 'shore power'.
The trip circuit on the generator does work, in the early part of charging my three batteries (with two chargers) trying the A/C will trip the overload. This should not work, but so far it seem to?!
I am not planning on using this, on anything past idle this cheap generator is LOUD, I just find this result 'most puzzling' and was wondering if others had any comments?

[JiminDenver]

Our Champ will run the AC with all the breakers on at 5280 ft in Denver. It's at close to 10,000 that I have to shut off the converters breaker.

Even at sea level I wouldn't expect it to run two ACs.

[ken07734]

Interesting, as I have a 3500 something..ahh Can't remember but it's red. Anyway, I can run the A/C which is a 13.5 in my Z-1 and it will stay running without tripping as long as I keep ALL breakers off except the AC. Go figure!

[EldIr]

The biggest difference when right on the edge is going to be the individual a/c unit. Does it have a hard start cap from the factory? How old is it? How tight is the compressor? Even among identical units there can be enough difference in manufacturing tolerance that one might start and one will not.

We have a Yamaha 2400is that will not start the 13.5 in the camper. It also will not start a brand new 12amp electric log splitter. I suspect it has a lot to do with being the very first year these gens came out. Newer ones, especially the HC, will work better. It will start a 10k window unit at our cabin as long as nothing else is plugged in until after the a/c is running.

The Champion 3500/4000 I picked up this year easily starts the 13.5 and the log splitter. It also means we can leave the Yammie at the cabin and not have to take it back and forth when going camping.

[pianotuna]

Hi horton333,

I went with the Yamaha 3000 sIEB as it has a ten second boost of 500 watts powered from the unit's starting battery.

If you travel to the mountains you may find the one you have will no longer "do the deed". If that is the case there are three inverters that will "boost" using the RV battery bank (magnum, victron and mastercharge) I'd pick the Victron if my pockets were that deep.

Since you have offered to design one--put in a larger starting battery and a longer boost time? (or even more boost?). I would want 3600 VA instead of the 2800 VA that is in the Yamaha.

[TomG2]

I have had good luck with three out of four Dometic 13.5k air conditioners running off a Honda 2000. This was at elevations under 1,000 feet. Starting is the trick, as mine "run" with about 1300 watts which is well within their rating.

[horton333]

So those very expensive Honda's (but they are quiet) are scrimping on the specs, sigh.
Ya know I am mainly retired now, maybe an interesting hobby would be to design a better generator ....

[wa8yxm]

The problem with 2,000 watt generators is many of them, epically the HONDA Inverter generators are **NOT** 2,000 watt generators,

I forget the continous duty rating but 1760 seems to chime. 2,000 is the peak

yours is 2200 peak, It is a real 2,000 watt generator.

I used to have a 1,000 watt enclosed generator (non-inverter) that routinelly hit 12 hundred watts long term.. Ran good. Would love to have it back but alas it grew legs on me.

[horton333]

I guess I did misread them / didn't pay enough attention, thanks. It is marginal, and the bulk charging stage definitely put me over the limit (and this was day time, no lights / microwave and neither of the computers running).
Just for fun I did check the voltage as mentioned, it stays pretty stable actually. Only goes down about 2 volts RMS between idling and the A/C full on (measured at the generator plug). I expect heat inside the electronics of the inverter would be the big stress if this was tied on any regular basis.

[JiminDenver]

Most of the time this is discussed it is with something like a Honda 2000 which has 1600w running and a shorter 2000w surge. Yours has 2000w running and a 2200w surge, thats a big difference.

When I asked how big of a generator to run our AC (Coleman 13.5) I was told 2600w to start and 2400w to run. If you have a more efficient unit at sea level I can see it doing it. I do agree it wont be good for the AC or the generator in the long run.

[mlts22]

I've heard about 13.5 kBTU A/Cs running on a 2000 watt generator, so it can be done if the generator can handle the locked rotor amps.

It is running on the ragged edge of the generator though, so I'd see about a voltmeter just to make sure that voltage is within normal specs... too low and the compressor may burn out.

[tvman44]

2Kw is kind of shy for a A/C. 😞

[naturist]

I think you misread -- all the threads I've seen have said that a 2,000 watt generator is marginal, i.e., 2000 watts is right at the surge rating for a 13,500 btu AC, so maybe it would work, maybe not. A 2200 watt surge generator ought to work, but the kicker would be if your house battery was discharged and the converter trying to charge it up, there's no way a 2,000 surge genny would work, and a 2200 watt probably would not, because the battery charging function would take around 600 watts off the top.

I am not a bit surprised your 2200 watt genny can do it. That extra 200 watts makes a difference when you are near "the line."