Forum Discussion
16 Replies
- SoundGuyExplorer
ReferDog wrote:
Locked rotor amps=same as if it was seize-up for 1second generator won't handle it. Looked into a START CAPAITOR ON THE A/C compressor this helps reduce the starting load.
Successfully starting any A/C compressor is all about LRA ... anyone who bothers to check out the Micro-Air Easy Start Soft Starter which I linked to above should easily understand why this A/C compressor start accessory which reduces start up current by 65 - 75% is far superior to just simply adding a hard start cap. :R - ReferDogExplorerLocked rotor amps=same as if it was seize-up for 1second generator won't handle it. Looked into a START CAPAITOR ON THE A/C compressor this helps reduce the starting load.
- SoundGuyExplorer
naturist wrote:
Guys who like to live on the edge, or who are too poor or too cheap to spring for a 3,000 watt generator (or bigger) might be able to use the smaller generator. But they are not likely to ultimately be happy with it. Just saying . . . .
Apparently you chose to not bother investigating the Micro Air soft start system discussion I linked to earlier :R so here's the manufacturer's link to this product which will allow successful starting of a typical 13,500 BTU roof mounted A/C unit with a typical 2000 watt genset. Technology marches on. :W - naturistNomadI see where he tried it and it did not work.
Let's be honest here, folks, and note that there is some variation in the numbers on everything. 13,5 K ACs generally require 1900 to 2300 starting watts. Exactly how much a particular AC unit needs depends on the make, model, age, and size/condition of the starting capacitors in that unit. The exact true output of generators varies as well, and over the same criteria. The result is that if you grab any generator in the 2000 watt class and try to run any AC on any camper in the campground, you will find some combinations that work, and some that don't. As a result, the best that can be said here is that a 2,000-2,500 watt generator is marginal at best, and that further depends on how much power the RV's rig is demanding at the moment to charge the house batteries.
Guys who like to live on the edge, or who are too poor or too cheap to spring for a 3,000 watt generator (or bigger) might be able to use the smaller generator. But they are not likely to ultimately be happy with it. Just saying . . . . - SoundGuyExplorer
ktmrfs wrote:
from what folks on the forum have said, dometic AC units seem to be easier to start than Coleman.
Anecdotally I'd have to disagree ... my Coleman Mach 3+ 13.5K BTU A/C started much easier, whether on shore power or genset, than my current Dometic Brisk II 13.5K BTU A/C under similar conditions and both equipped with an SPP6 hard start cap. Those running a ducted system controlled by a wall mount thermostat can in either case though reduce the start up load somewhat by wiring in a LO/ HI fan speed switch with a centre off position which allows one to start just the A/C compressor first, then manually start the fan once the compressor is up to speed and the genset has stabilized. - ktmrfsExplorer II
mdprowash wrote:
Thanks for the feedback.. i gave it a try and it won't handle the startup load.
well, you tried, and your experience is very very common with a generator under about 3,000W.
from what folks on the forum have said, dometic AC units seem to be easier to start than Coleman. But it's a case of the generator being "almost adequate" rather than "barely adequate". NOT the same! - SoundGuyExplorer
mdprowash wrote:
Thanks for the feedback.. i gave it a try and it won't handle the startup load.
I'm one of those who has owned 2 Honda EU2000i gensets that under favourable conditions would successfully start & run 13,500 BTU Coleman and Dometic A/Cs ... but not under all conditions. Eventually I decided it just wasn't important enough to me to listen to any genset rattle away all day long just so we could run A/C and I sold both. However, if it's really important to you check out this recent discussion about adding a MicroAir start system to your A/C. - mdprowashExplorerThanks for the feedback.. i gave it a try and it won't handle the startup load.
- LIKE2BUILDExplorerWatts = Volts x Amps
2300W / 120V = 19amps
It might do it, but that's assuming nothing else is running and the load on the A/C isn't too high. I used to have a Generac rated at 3750W startup but it couldn't handle my A/C starting. in my case I finally discovered it was rated for a max 27.1amps, but since it was 240V that amperage was divided between the two 120V legs so I only had an effective 13.5amps for my RV plug. UGGHHH, expensive lesson!! - ktmrfsExplorer IIit's the start locked rotor amps that kills most generators. they can't deliver 45 amps or so for startup long enough to get the motor rotating. IF you can get it to start, it likely will keep it running.
Now some air conditions are better than others at starting, but they all suffer the same issue with a conventional cap start induction motor, high inrush current demands and high current until rpm is up enough that the back emf reduces running current.
Now if the switched to the electronic motor controls and high frequency motors used in many house appliances, would be a much easier job.
and just because it starts it at sea level on an 80 degree day doesn't indicate if it will start at 95 degrees, or at high altitude, or both.
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