Onan RV QG 5500 amp question

[JohnTaylorTX]

We have a 2014 Grand Design Momentum 355TH with a Cummins Onan RV QG 5500 EVAP generator. From everything I have read this generator it is a 50 amp generator. Even the labeling on the outside 'Shore power' says 50 amps and the generator has 2 x 30-amp breakers in it too. I find it odd how after we power on 2 A/C's, refrig, water pump and a couple other things it is around 39 amps but once it gets past 40 amps it acts as if it gets tripped and never reaches 50 amps. So once it is tripped (or overloaded?) now both A/Cs power off and generator goes back to idle and my EMS Control panel goes blank. I checked that both of my 30-amp breakers are just fine. Eventually the 'power' EMS control panel lights up and shows GEN and then after several minutes the other right lights up (W/H, A/C-RR, A/C-FRT, A/C-MID) as if it reset itself. Then I can power up both A/C units again. If I only run the 2 A/C's, have the refrig on Propane and all other main switches off, then it stays consistent around 30 amps and on some hot days it gets up to 35 amps based on what the Power Control system states.
So is it normal for this generator to not support true 50 amps? Just an FYI, I have done the complete maintenance on this generator such as oil change, oil filter, air filter, Fuel Filter, Fuel Pump, and replaced both 2 spark plugs (with proper gap) plus even did the SeaFoam cleaning of the carb too. I'm scratching my head thinking it should do more then 40 amps or am I thinking incorrectly?

[howson]

I'm not an expert on generators--I just googled the generator and found the manual. https://powersuite.cummins.com/PS5/P...ets/a-1425.pdf

The max the generator will provide is 5500 watts, or 45.8 amps.



When an air conditioner compressor kicks on it pulls a very high initial startup current. What could be happening is as your systems cycle this startup surge overwhelms the generator's capacity. If I'm reading Dometic's documentation correctly (I could be wrong) the compressor can pull up to 71 amps in some situations! https://www.dometic.com/en-us/us/pro...ii-air-_-20679





IF (repeat: if) I'm right an option is an EasyStart. I installed them in both of my Colemans and can start (and run) both air conditioners off of a 3000W inverter. (I've done it--not for long but it works!) This thread has more info: https://gdrvowners.com/forum/operati...s-2019-315rlts

Again--I'm no expert so could be completely off-base on my analysis. Hopefully a Momentum owner will chime in here soon.

Howard

[ThePowells]

Ours runs everything that we want to. When I shook it down after the installation I ran both A/Cs, water heater, pump, every light, washing machine and dryer for over 30 minutes. After then, it was getting too cold to keep running the A/C and went to heat pump and furnace.

[JohnTaylorTX]

So that means the Generator only will go up to about 45.8 Amps which would make me believe i was right about not reaching 50 amps. Thank you.
What about when I am plugged into a 50 amp shore power outlet, then do I get true 50 amps?

[howson]

So that means the Generator only will go up to about 45.8 Amps which would make me believe i was right about not reaching 50 amps. Thank you.
What about when I am plugged into a 50 amp shore power outlet, then do I get true 50 amps?

When connected to a 50A shore power connection, there's actually two 50A lines feeding two separate circuits in your camper. Did you know that? Below is an (old) outline of my 315RLTS showing "L1" and "L2". Note the two 50A main circuit breakers. I suspect your trailer is setup similarly.

What this means is there is potentially 100A available (if the pedestal can provide it), 50A to each "leg". The generator can provide less than half that amount of current.



ThePowells
has a 2020 trailer with Coleman air conditioners. The newer a/c units (I think) do not draw as much current upon startup, thus why I think they can get away with running off of their generator.

[ThePowells]

And I forgot, I ran the microwave to boil water. I didn't think to fire up one of SWMBO hair dryers. That one has been known to shut down an entire campground.