Electrical Issue

Took the RV on a road trip this past weekend. Going down we ran the genset with A/C, fridge and the kids watching TV/DVD in the back - no problems. Once at our location, switched over to shorepower (20 AMP) to run A/C, Fridge and watched a little tv on the main screen - no problems again.

Headed home, switched from shorepower back to genset, again using the same items on the trip down, except this time that even with the genset running with no issues, something like a circuit breaker kept tripping. We could shut of the battery disconnect switch, wait a bit and turn it back on, then everything would work again for a short while before going out again.

Finally turned off the switch and waited about 15-20 minutes, turned it back on, brought up the genset but only had the fridge and TV/DVD in the back on this time. Ran like this for about a 100 miles with no issues, then kicked on the A/C and ran the final 100+ to home with no problems. Reached the driveway and while unloading we left the genset running and something tripped again to kill the A/C, fridge and tv. I parked it and plugged it back to shorepower and everything seems fine.

Sorry for the long post, but where do I look first???

rutherford.ms said:

something like a circuit breaker kept tripping.

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Was it a circuit breaker or just an unidentified noise you heard?

No, none of the breakers were tripping, but of course with the A/C running you knew when it switched off. With the A/C off, you could hear it just like hitting the battery disconnect switch.

I'm guessing it's some sort of thermal overload.  The fact that it only happens on generator power and that it was necessary to activate the battery disconnect to allow the condition to clear is very perplexing.  At this juncture we don't know if we are chasing an AC or DC problem.

One could visualize a thermal overload in the generator, but requiring removal of the 12V-DC doesn't logically factor into it's ability to cool down and reset.

All 12V circuits are pretty much common regardless of whether on shore power, generator or just battery power.  The one exception may by 12v usage within the generator (other than starter voltage).

Can you recall any further details of the symptoms?

Did all interior lights fail during the drop out?

Was it really necessary to switch the disconnect, or could it have just been the time element?

Do you know if the disconnect solenoids are in a box labeled Intellitec or RV-CP?

Sorry for more questions, rather than answers, but you've posed a real teaser here? ???

You may have a point about whether we really "needed" to turn the battery disconnect on and off or not. And mind you we were not stopping to check this out, so options were a bit limited. With the Air Conditioning and other A/C applications going off, the only method we appeared to have for any restoration of power was to reset that switch. And of course resetting the switch would shutdown the generator too. So it was reset the switch, re-start the genset and the A/C applications would be on again. Initially we did this several times, then finally tried to isolate the issue as I described in my initial post. With all of the A/C applications running except for the air conditioning, all was fine for over a 100 miles. We then figured it was worth adding the air back into the equation and finished our trip, roughly another 150 miles without any further interuption in power. One thing that I have thought about is that when we were back in the home driveway, there's a good chance that the air shut off due to the thermostat and not a loss of power. I think I was so fixated on the power problem that I just made an assumption there without actually checking to see if anything else on A/C had stopped working.

I want to make sure that I am clear on one issue. My understanding is that whether you are connected to shorepower or genset, the actual power transfer through the automated switch is the same. Logically I would think that you are simply connecting voltage via the same cable either way.

I will check the type of box this afternoon and post that information.

Thanks, Charlie

I want to make sure that I am clear on one issue. My understanding is that whether you are connected to shorepower or genset, the actual power transfer through the automated switch is the same. Logically I would think that you are simply connecting voltage via the same cable either way.

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That is correct.

And of course resetting the switch would shutdown the generator too.

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That's bizarre - I can't think of any reason why the battery disconnect would shut of the genset, unless it was somehow relying on the battery to keep it's ignition hot. That in itself suggests a problem, since the generator engine should be self-sustaining once it is running.

RV Roamer said:

That's bizarre - I can't think of any reason why the battery disconnect would shut of the genset, unless it was somehow relying on the battery to keep it's ignition hot. That in itself suggests a problem, since the generator engine should be self-sustaining once it is running.

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Gary - wouldn't a gas genny shut off?  Diesel only needs air and fuel to run, a gas gen set should also need 12V for ignition unless it has a magneto.

RV Roamer said:

That's bizarre - I can't think of any reason why the battery disconnect would shut of the genset, unless it was somehow relying on the battery to keep it's ignition hot.

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Gary,

That is the way my motor home functions. I can turn the genset off at the dash by hitting the Aux Bat switch and disconnecting the coach batteries. My genset starts and runs from the coach batteries and not the chassis battery. Usually when traveling and my coach batteries are fairly discharged after a night of cold weather boondocking, I prefer to charge them with the genset rather than the engine alternator. After a couple of hours on the road, I hit the coach disconnect switch and shut the genset off--saves having my wife get up and hit the genset STOP switch. After I shut the genset down, I then reconnect the coach batteries and hit the dual batt switch to put the alternator to work finishing charging of the coach batteries.

RV Roamer said:

That is correct.

That's bizarre - I can't think of any reason why the battery disconnect would shut of the genset, unless it was somehow relying on the battery to keep it's ignition hot. That in itself suggests a problem, since the generator engine should be self-sustaining once it is running.

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That one is easy Roamer and .. You are exceeding close to the fact...  The Generator does indeed use 12vdc to power some of it's electronics, Now a Stand Alone generator makes it's own 12vdc, but a unit designed specifically for RV use "Borrows" a small amount of 12vdc from the house systems.

So if the A/C to the house goes out..... Which is the problem this person is having, then the converter is no longer supplying 12vdc

And if you then disconnect the battery.. It's all gone. so the generator shuts down,,, Just like someone had turned the ignition key on a car, in fact, for the exact same reason. NO 12vdc

It wasn't clear from the initial post that the generator kept running when the power was lost.  Now that we know that fact, it looks like the AC is being lost from the generator to the main panel.

Nothing but a transfer switch in between ???

If the transfer switch was dropping out from vibration, it should immediately re-energize since the generator has override priority.

If it was a loose connection, I wouldn't think it would reset so reliably.

If it's heat related, it could be in the transfer switch or the generator output stage and could require a shutdown to reset.

Most small gas engines do have a magneto and don't need external 12v, but I guess the gas engine in an RV generator does not, based on what you all are reporting. They probably figure they need 12v to start anyway, so why not "borrow' some as John describes it. I stand corrected!  8)

"No day is wasted if you learn something"

No problem Roamer.. I too assumed the Genny would be a Magneto type.  There are several advantages to Magneto ignition systems.

And for all I know it may well be

But there is a control computer in that turkey too..  All I know is that my generator needs 12vdc to run, no 12 volts, it stops

Might be as simple as a locking relay ignition switch

Sorry about not coming back on this post, but have been too busy to do any additional troubleshooting on the problem. At this point it has remained parked and on shore power. I do intend to take a short trip this coming weekend so will have an opportunity to see if the issue still persists.

And on the question of the genset shutting down due to turning off the battery switch, I was told that the switch was also a safety device and that whenever I refuel the rig to turn off that switch - which I do and everything does shut down. I just always assumed that the power circuit was designed in this fashion so I have never questioned it.

Turning off the ignition switch does NOT make your rig safe to fuel. Any propane powered appliance that is on  will remains on and any source of flame or spark can cause an explosion if there are gasoline fumes in the air. Diesel is very difficult to fire under the same conditions, though.

Follow-up: My mistake - the original message talked about turning off the house battery disconnect. That should stop 12v appliances from running or attempting to run.

Gary I am not sure if Rutherford was talking about the ignition switch. I deduced it as being the master house battery switch.

  In my case, when I kill the house switch all power is killed on the 12 volt side in the RV.
I generally make sure the fridge and water heater switch is off as. Probably isn't necessary.

FWIW, carson

Right you are, Carson.    Mea culpa!  :-[  I added a note to my previous post to correct it.

Sounds as if a transfer switch that connects the coach 120VAC system to either the generator or shore power may be dropping out. The OP does not state what type of coach the problem occurred in so we can only guess what type of transfer switch it has or even if it has one.

Made another road trip yesterday, pretty much the same problem although I did find out a few additional details. The genset runs okay period, puts out 115v as it should and outlets, fridge, tvs, etc work okay. Turn on the A/C and apparently the load causes some type of switch to cut out and everything using 115v quits. The genset continues running (I am not touching the battery disconnect switch), but the 115v is gone. Bring the rig back home, connect to shore power and all 115v devices are fine, including running the A/C (which has now been going steady for 36 hours+).

I will ask this again as this is the part that I cannot figure out. IF supposedly power whether from the genset or shore power is connected through the same circuit, then this problem should not be occurring. How can everything work just fine on shore power, but connecting power from the genset cannot handle the load of the A/C? I am also assuming that if I were to try the microwave the same problem would happen too. Rig is going into the dealer tomorrow as I need this fixed, but I am confused as all get out on this one.

You have tripped the circuit breaker on the generator.  What is the make and model of the generator?

Hmmmm.....

Could this be a problem with an energy management system?