Generator size to run a 17.56-2

Ligedy

Active Member
Oct 13, 2012
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Mackay
We went over to Lake Elphinstone over the weekend for a day trip. One of the guys I work with was running his Heron 2.2 with his Honda EU20i, I cant for the life of me work out why mine won't. I have tried to run the lead directly to the A/C this morning which will bypass all the other 240V circuits in the Expanda. Still won't run. I want to buy a generator but am very hesitant due to the dramas I am having. Don't really want to fork out $$$ to find out it won't run.

I am also hoping there isn't something wrong with the A/C...
Will the A/C not run at all or will the genset overload when the A/C is turned on/compressor kicks in?

Have you tried running the A/C on mains power at home recently? If a capacitor or other motor failure is present on your Herron I’d expect it to trip out or not run off mains power either... trip to the A/C repair man warranted.

The only other reason I can think of is the start-up current is too much for the genset but that doesn’t explain why an the Honda2 will start the same A/C elsewhere... After starting, running the Herron 2.2 off a Honda2 doesn’t look like it’d be an issue for cooling.

Know any sparkies? Ask them why a locked rotor current of 18A doesn’t trip out a 15A/10A breaker on the mains feed or 8.3A genset? Some of air commands other A/C models show 20A LRC. I’m guessing, again, that it’s only for a split second that allow it to kick off the motor then keep running at operating current without tripping a breaker or genset overload. Borrowing a tong tester to check current draw when running of mains might be helpful to see what current it really pulls when the compressor motor kicks in, and thus show how hard a genset has to work to run your specific A/C.

kW = effective power flowing from the source to the load. Honda EU20i = 240V x 8.33A = 2000W or 2kW max output / 240V x 6.66A = 1600W rated output

kVA = is the power circulating between the source and the load and is also known as the reactive volt-amperes, which is the useable power of a generator. AC devices require reactive power, which also has to be supplied by the generator known as the power factor (pF). Honda rate the pF at 1.0 so the kVA is essentially the same as the kW rating, some other brands use pF of 0.8 generally resulting a lower usable power rating…

From the manufacturer’s specs - to run the Herron 2.2 on:
Start-up: Locked rotor current of up to 240V x 18A = 4320VA. (typical start up power at 4.5 x 4.0A running current for split phase motors) Might only be for a split second allowing the Honda to keep running whilst the A/C compressor motor kicks off. The Honda is rated for 2000VA max = 8.3A.

Cooling: 240V x 4.0A x 1.0 pF = 960kVA = OK load to run of Honda EU20i. Plenty of capacity to keep the Herron running. As @Coastrunner mentioned an EU10i has enough power to run the Herron 2.2, although I think it would struggle with hot ambient temps. (2.2kW cooling capacity is the energy rating the A/C can cool the air/remove heat from the air).

Heating: 240V x 6.5A x 1.0 pF = 1560kVA pushing the genset to its Rated output (1600kVA), so not as good – go for a bigger genset. (1.5kW heating capacity is the energy rating the A/C can heat the air).
 

Brad

Well-Known Member
Jan 2, 2012
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Rowville, Victoria
I was concerned about a honda EU20i running my truma a/c before buying one... But with first cyclone of the season I just bought one today for the house anyway.

Came across this the other day - http://www.modmyrv.com/2009/05/27/rv-air-conditioner-hard-start-capacitor. I will run it past an electrical engineer at work next week and see if it's worth doing anyway.
That's not a bad forum you found with all the mods. I like the way they have categorized everything.
 
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Hubble80

Well-Known Member
Nov 22, 2012
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Moranbah, QLD
Thanks for all the replies guys! @Ligedy thanks for the technical info. I am in fact a sparky myself so I will be looking into the soft start option this weekend (need something to do with the rain around from the cyclone!)

I haven't tried the A/C on 240V since coming back from holidays of Christmas and it ran fine then, so hopefully it hasn't blown a starting capacitor in that time.

I sent an inquiry to Aircommand themselves and they say you need a minimum of a 2.8kva generator to run the unit! OBviously by what everyone here is saying you don't. But I guess that would be spoken from a warranty/design point of view!
 

Ligedy

Active Member
Oct 13, 2012
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Mackay
Well mate hope you get of sussed. Let me know what you find it to be.

My Truma Aventa must have a decent capacitor or soft start setup. It says it pulls 28A for 150ms @ start up. The new Honda EU20i - started it up and it ran it for 30 mins with no hesitation (H2 --> ampfibian --> 10m 10a ext lead --> panda).

I didn't buy it to run the a/c and don't think I want to coz it makes a bit of noise running at full speed...
 

jimgoose

New Member
Mar 31, 2011
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Mernda, Vic
We bought a cheapie like this back in May 2012 off ebay, paid $500 for it.
Runs Air Con, Micro, Elec Fry Pan, Sandwich Maker, Kettle, Decoder etc. Done 20 hours which is not much and the only dodgey thing was flat battery for lack of use.
It's not really silent.
If I was doing some serious travel then I think I would go a Yamaha or Honda.
Otherwise the ebay great buy is for us.
View attachment 18194
Hi all
We also run one of these eBay jobs and it's still going fine after over 100 hours. Runs the aircon no worries at all. I do find it to be a little cumbersome compared to the Honda 20i I used to have tho. It has small wheels at the back and a pull out handle to to drag it around which is a good idea but its next to useless in the bush or on anything but the flatest ground as the wheels are so small. It comes with a remote control which is also next to useless as you need to be within about ten meteres for it to work. I DO like the electric start tho!

Overall I think its very good value as it serves it main function without fault and when put beside my camp buddies Honda 2 is only slightly louder.