Onan Fuel Usage and problem

[avvidclif]

We dry camped over the 4th weekend for the first time in our new RV. Had a great time. We arrived abt 10:30 Fri and started the Generator abt 11. It ran until the next morning when I shut it down and checked the oil. Started it back up and ran it until abt 11 on Sun morn. The clock showed 45+ hrs and when I filled the tank back up on the way home and we had burned 25 gal. As you can figure the AC ran most of the time. Plus fridge, etc.... Normal usage except the WH was on gas. I did cheat a little as we dumped in 5 gal Sat afternoon and another 5 Sat nite as I didn't want to run short in the night. Then topped it off with 15 gal at the station on the way home.

The problem. I turned on a second AC and the Transfer switch chattered for several seconds and quit chattering but I still had power. I turned off the second AC figuring the circuit for the second AC (garage) was on the other circuit and it was not as tight as it should have been. I didn't feel like digging around in the hot generator compartment in the heat so saved that for after I get home. I know the shore power side is fine as I've run 2 AC's before. That leaves the connections from the generator to the transfer switch (box on wall beside generator) and as I know the transfer switch connections are tight because I checked them when I installed the Surge Suppressor.

Overall very pleased with the operation. Since I have a 30 gal tank and the pump quits when it's down to 5 gal (not sure about the generator) I figure a full tank and 5 gal will get me thru a weekend. Nice to know. Of course once I get both Ac's going it will be less but still not bad.

Kudos to Heartland and Onan for the setup. The generator is actually louder outside than in the RV. The bed is right over it and I couldn't tell it was running while sleeping I was well pleased.

 

[MTPockets]

Our campground lost power last week for five hrs in mid afternoon until power company could replace transformer. Our Onan is propane, but also got some of that transfer switch chatter. Two A/C's were working fine for a couple hrs, but when we turned on an inside fan, then the microwave the chatter flared up. I turned off the fan and electric water heater and we were good.. I guess when you're drawing too close, or over 50 amps, that will happen.

 

[avvidclif]

My understanding is when the voltage falls below 104v the Transfer switch cuts out. Since 2 AC's should not be a full load for it I'm looking for a connection that is not tight enough.

 

[porthole]

Are the two AC's on separate branches of the circuit breaker panel?

Shore power - 50 amps x 2 branches = 100 amps (12,000 watts) regardless of temperature or elevation.
Genny, 5500 watts = 46 amps, controlled by 2 independent 30 amp breakers. And, that is at a set altitude and temperature. If either goes up - output goes down.

So, it is possible one AC may be running with a 10-12 amp load
The 2nd AC may be trying to come on with a 10-15 load, and if by chance your power converter is on the same circuit, it could be adding 10 -12 amps as well.

Either way, just two AC's and the converter could be drawing close to 40 amps, out of a best case of 46 amps.

Anything else plugged in to any of the outlets?

The box on the wall by the generator should just be a junction box.

 

[Jim.Allison]

Chatter = not enough voltage available. probably because the generator takes a second to get spooled up. Which means you are right on the edge of what your generator can do. I have an inverter that fills in while the generator spools up, it responds in about 1/24,000 of a second and only last for a few seconds. The inverter also balances the two legs which is very helpful also. If need be the inverter will supply the missing power as long as it is needed, but this could be problematic, I avoid this scenario.