Forum Discussion

gb76087's avatar
gb76087
Explorer
Oct 17, 2020

Generator and A/C question

30 amp coach, 2 Coleman 13.5 A/Cs, Intellitec controls(with shedding) and an Onan 5500 generator.
While exercising the generator,the front A/C would constantlay switch between shed and on. Eventually it will end up running for a period of time,then goes back to switching back and forth, then running again. When I turn on the rear A/C, it begins running almost immediately, shedding intermittingly,but running as I would expect. The front A/C continues to shed and run.
I can hear the generator rpm's varying and it appears that when the rpm's increase the A/Cs both run.
Not sure where to begin, assuming there is a problem. Looking for other's input.
  • Thirty amps is right on the edge for 2 13.5 units.

    What else is running?

    You might solve it with a hybrid inverter charger. I'd prefer Victron or Outback
  • If you've just started the generator for exercising and the MH has not been plugged in, then the battery charger is probably kicking on at the same time. If you have four house batteries, the charger is probably drawing a larger load than you expect.

    Bill
  • Thanks for the responses.
    Nothing else running. The "shed"ability lets both A/Cs run but not start at the same time. This is a gas coach,only 2 batteries, no inverted,just converter.
    My main question is why does the front A/C have so much trouble starting and continue running when it is the only thing running on the generator? What do i need to be checking?
  • Is the water heater also heating on electric? Is the converter charging some low batteries?
    Otherwise you need to get into the load shed system and see what the priorities are, what is pulling power, and how much power and voltage is moving through the circuits. May need a clamp-on ammeter to measure what is going on.
  • Need to research the running A/C amps with fan on High and the peak turn on amps. Starting 2 units will far exceed 30 Peak Start up Amps.
  • 5500VA is around 47+ amps at 115 vac
    Motors including A/C compressors have around a 0.96 Power Factor
    You have enough generator for two A/C units
    The problem is the Intellitec load shedding power management, the current transformer sensor, is on the power input hot line to the Main Breaker for your panel, the Intellitec system is set for 30 amps for the shore cord input to prevent overload,
    On my MH , a 1997 Bounder there is an extra circuit breaker in the service panel, to put one A/C on the second winding from the 5500 Onan, and avoid having both units on the "measured" hot wire of winding number 1 that's feeds the main breaker

    Some RVs (example 1992 Komfort 31ft) come with an extra 120v switch , for switching one of the a/C's between shore and generator, in my case here in the Bounder, that's the extra circuit breaker wiring
    Do you have either of these in your RV, check to see if it's in the correct position for generator use
    If not
    There is an extra load turned on
    Front a)c has problems
    Your two batteries are drawing more charge than you think, to check turn off or unplug converter,
    Or charge batteries 30 minutes before turning on the a/c units
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    He may have a 30 amp coach but that's a 50 amp generator
    His problem is with one of 3 things
    The intelletec controller is not sensing the generator properly (Since I don't know how it senses generator power I can't say more about that)

    THe Auto Transfer switch is the wrong one or wired improperly

    A Switch is set improperly

    When running on Generator one of the A/C's is supposed to be powered by the 20 amp breaker on the Genny. Directly, Via the Auto T ransfer switch IT does not

    It may be other loads (like water heater) causing the sheding as well I do not know.
  • FIRST thing is a AMP check of BOTH AC units. Your AC units will not pull over 30 amps together, even including the micro second start up of the compressor. That leaves 18 amps of power left for other appliances. So, you need to make sure your Water Heater(10.5 amps) is off. Since you have a CONVERTER, it will not pull more than 3 to 5 amps. The culprit is probably your old AC compressors. Doug