No AC power from generator.

[Carol Moffett]

Help!   Our 10kw generator starts and runs great but it's not putting out any AC!  Inverter works but battery charger won't come on and all works well on shore power.   What could be wrong or what are we missing?  We have much dry camping to do in our near future, in Chandler for one, and are on the road right now!   Thanks for any help!
Carol and Keith

[Joe Rhea]

Did you check the breaker on the genset?

[Carol Moffett]

Thank you, Joe,
Yes, Keith checked the breaker and it seems to be good.  I can't help but feel it's got to be a simple thing because everything else is working so well.  Probably wishful thinking, tho, lol!  Sigh
Carol

[Steve Huber Co-Admin]

Carol,
Assuming there are no generator codes, make sure the breakers on are on at the breaker panel. (Located in bathroom in our 07 Contessa). If they are on  it sounds like the transfer relay may have failed. If Keith is handy he can check to see (carefully) if AC is coming in from the generator to the relay.
Steve

[Keith Moffett]

Steve
Do you mean the power transfer switch or is there also a relay somewhere?
I didnt have any codes on the generator itself and the breaker on the generator is set on.  There are no thrown breakers in the a/c service panel.
The Aladdin read  12.3 V on the house batts with 11A.  It said "no a/c present" and the remote on the Magnum would not turn on the charge.  I will check for a breaker on the inverter tomorrow but the inverter function was working and the charge function works when on shore power.

Thanks
Keith

[Fred Brooks]

    Hi Keith & Carol,
 On the back side of the transfer relay cover you will find the schematic of how it is configured and the incoming power sources. Locate the Generator wiring coming into the relay box and the relay it is going to. Carefully with your multi-meter touch the leads to the red wire and the white wire and it should say "120 volts a/c" if the power from the generator is present. If it is next put the leads on the black wire and the white wire. If it says " 120 volts a/c" then you have proven that the generator is working properly but the 120 volts is not transferring thru the relays into the coach circuit breaker panel. If no 120 volts at the points you just checked, the issue is in the generator.
    Hope this helps, Fred

[Dan Murphy]

Keith this happened to us once and we had to replace the transfer switch. It was not allowing the power to pass thru from the generator.It might be possible to reset the switch but be very careful. Take the cover off the transfer switch and watch as you start the generator and see if the breaker inside the switch cuts out.
We were dry camping and if I remember correctly we forced the breaker to stay on until we could replace the faulty transfer switch completely.

[Edward Buker]

The breaker on the genset can look like it is on but needs to be turned off and back on to reset it. This may be wishful thinking that it is that simple. I was not sure if Kieth was aware of that. Like Fred and the rest have said, the next stop is the transfer switch...

If you find you are losing power between the genset and the transfer switch there is a terminal block in the top back left corner of the genset under a small plate. Small chance wires could have loosened there, I had an issue with one leg coupling there. Heading away from the genset junction block, on the back right of the storage bay there is a metal junction box with wire nuts that couples the genset lead to the house wiring that then heads to the transfer switch. Not likely that these junction boxes are the issue but thought the info would save a hunt if the problem was elsewhere.

Later Ed

[Steve Huber Co-Admin]

Keith,
My error. Missed that you were ok on shore power. As Fred noted, you can check geni voltage at transfer switch, Red and Black wires are hot and White is neutral so you should see 120v from white to both red and black.
Steve

[Edward Buker]

Kieth,

My wiring info on my last post was for an older coach and may not apply, forgot that you have a newer motorhome now. Sorry for any confusion...

Later Ed

[Keith Moffett]

Ok so here's the update.  This is a good one for the books.
In prep for our trip starting yesterday, I changed the air filter in the generator.  There was so much dirt in the filter area of the onan box  that I used a low pressure air to blow it out prior to pulli g the filter.  The generator worked up to then but the coach is new to us. 
Aparently something caused the breaker switch to pop but as stated above it doesnt always show that it needs to be reset.  The generator failure showed up 15 minutes prior to departing for AZ yesterday so I have been fretting about this for two days.
After the breaker was reset we are up and running.  It was the first thing I checked but didnt think to reset it because it wasnt dislodged like a breaker will but it was indeed the problem!
Thanks everyone for the insight and step by step solution.  Major relief here.

Keith

[Lee Welbanks]

Keith,

I would bet a few dollars you will not forget that one. When checking circuit breakers always switch them off and then back on. I've seen breakers that are tripped and the switch handle never moves at all. If you grab it, it will feel loose, off/on done.

[Bill Sprague]

Keith and Carol,

Our Monterey was certainly different than your coach.  However, it had a habit of mysteriously tripping the breaker on the genset.  Maybe yours is similar.

The answer turned out to be the Inverter/Battery charger.   On ours, the genset CB was a double 30 amp.  If the cleverly smart battery charger sensed that the batteries needed a charge it would immediately go to work at maximum effort drawing a lot of amps briefly.  So, if anything else with any significant load (like an air conditioner or the HydroHot) was on, one of the two 30 amp circuits would be briefly overloaded and the cause the breaker to trip.

In other words, it did not work like one big 60 amp/7500 watt genset.  It worked like a pair of 30 amp/3750 watt generators where each could shut down everything if one saw a brief overload.   

Have fun in AZ!  We should be following you.  The Puget Sound region weather suck!

Bill