Onan Generator breaker help

[nothermark]

Originally Posted by Eric1959

Transfer switch? Where would I find that on the converter or inverter?

Update. Had to jump start the house batteries from the chassis battery. Let them charge for a few minutes, started generator. Reason being the gen would not start. House bat's were below 9v

Generator would NOT charge batteries. Soon as we got packed up, slides in, we headed home. Stopped at Cabela's to dump tanks. House batteries were charged. I assume from the chassis system.

1. could the converter be going bad
2. would that cause the one generator breaker to trip

We also during out trip home could not get the AC units working, neither one of them, while the Generator was running and we were driving.

Plugged it in once we got home (110 ac), BOTH AC units would run, not at same time of course but each one ran fine.

So thats the update. Looking at replacing the converter anyways, it's OLD

If you have a separate Inverter and Converter you need to understand how they relate to each other. There are two common setups.

The "whole house" type inverter where the power shore cord and generator feed either side of a transfer switch. That switch feeds a distribution panel that feeds AC to the A/C's, water heater, and any other big AC loads. It also feeds AC to a large Inverter that has a second built in transfer switch as part of the Inverter. That takes in AC power and sends it to the AC outlets while also acting as a converter to feed 12 VDC to the battery and house circuits. That charges the battery while supplying lights and whatever. When shore and generator power is off then the Inverter transfer switch toggles and pulls 12 VDC from the batteries to feed 120 VAC to the house circuits.

The small inverter for special loads only type setup has an Inverter for dedicated loads like a residential refrigerator or large entertainment center and a converter for the 12 VDC and house battery charging. That type of setup does not feed 120 VAC to most of the sockets in the wall. It probably has one or two where the dedicated loads are connected as that is the most convenient way to do it. You don't have 120 VAC for most sockets when not on shore power or generator. Most of those will also have a small transfer relay for their loads to use 120 VAC when it is available. Some just take the efficiency hit and always invert the 12 VDC.

It sounds like you have the second setup. That or some kluge somebody probably not the factory put together. You will need to understand that.

In your case it sound like you have the small generator option for a 50 Amp shore service. That gives you two 30 Amp legs of 120 VAC each instead of two 50 Amp legs. More than enough for two A/C's, HW, battery charging and some ancillary loads. Not enough for 3 A/C's hair dryer, microwave and water heater all at once. Lower cost, lighter and more fuel efficient.

The reduced power generator has another issue in that you are feeding each 50 Amp panel leg with a 30 Amp breaker on the generator so the generator breaker will trip first. If you have managed to turn on something like 40 Amps of draw on one leg of your 120 VAC it will work on shore power but not on the generator as it will pop the 30 Amp breaker. The other option is a wiring problem.

It is a valid check to turn off the house 50 Amp breakers and see if the generator will run with both breakers on. If it does the wiring is probably OK. I would check the connections with the power off at at the generator and transfer switch. They tend to loosen for several reasons. Loose enough and they get hot and things melt. You need snug but not so tight you break things.

If you can run with the house breakers off and the generator breaker on the next step is to measure the current in each leg when on shore power. IF you are drawing over 30 Amps the breaker is doing it' s job and you need to sort out your loads. If you cannot run you have a shorted wire. Figure it out fix it or bypass it.

Your house batteries are not charging when on generator because the leg that is tripping is the one with the converter on it. The fact that it works on shore power would tell me you probably do not have a converter problem. More likely you have a load problem. You do need to make sure everything is working on 50 Amp shore service.

Most likely it will make no difference in anything but your wallet if you change the converter before you fix the problem.

[Eric1959]

Sorry but I failed to give the error code off the Gen that I I'm getting. I get 3 flashes. Then when I hit the stop button, I get 2, then 7 flashes. Code 27 which I read is a Voltage Sense Fault.

I get this when I flip breaker one ON and start it. Breaker 2 works fine, (bottom breaker)

To add to all this headache now my battery store switch won't work. I have the coach unplugged, and can't put the batteries into store mode. Hoping this is a separate issue that JUST cropped up but one thing at a time.

[twinboat]

The error is probably due to the short in the wire leading from that breaker.

The disconnect probably won't work due to dead batteries. Try starting the engine to give them a few minutes of charge, then try the disconnect.

If the batteries are dead, you want to charge them up. Letting them sit dead, will kill them for sure.

[Eric1959]

Update:

Hello again. Wanted to post an update on the Generator issue we've been having.. still.

After a runaround with our dealer which I won't go into, we took our coach over to a dedicated Cummins/Onan service cnt here in Columbus Ohio.

Recap.. our gen set would ONLY run off 1 of the 2 breakers, powering only half the coach, rear end mostly. Front Air, micro, front ac outlets, tv, not working.

Try to turn on both breakers, gen set would shut off after 2 or so seconds, flash code 27. Would not charge coach batteries either.

Plug unit into shore power, ALL works fine. (except gen of course)

Anyways, Cummins called a short time ago, was told they pulled the gen set out of the RV, hooked it up, it ran PERFECT.. both breakers on, full load, all was great with it. Only charged us $130.13 out the door for labor and test.

Was also told that it has to be wiring issue somewhere in the RV, from the gen set to where ever, that is causing a short back to the breaker cutting it off. They don't do that sort of work, so this is on me pretty much as I am not going back to the dealer.

Now. "could", the inverter cause this? I've already replaced the converter with a new one. I have had issues with the rig plugged in and having to reset the small breaker on the inverter.

Or am I looking at a cut wire, outlet bad, or what?

I'm HAPPY as hell our gen set is good! Dealer wanted $600.+ to do what Cummins did. The dealer also told me I had a bad choke pull off, Cummins said nothing is wrong with the choke.

[twinboat]

You say it works on shore power, it's not the inverter. Refer to post #11.

If you can't get a look at the wire from the generator to the transfer switch, have someone jump in a temporary one.

It is possible that the problem is in the transfer switch terminal board. A loose wire will cause your short.

[mfire1339]

I don't understand why your gen. get an immediate load when starting? Mine has a delay built in to allow the gen time warm before getting a load. 30 seconds maybe more. I think you need to open your transfer switch cover.




Mike

[twinboat]

Suggestion, call a mobile RV repairman. Tell him you need someone with electrical expertise.

[nothermark]

Thinking about your problem I would think you could learn a lot by turning off all the house breakers then starting the generator. Then turn on each breaker one at a time with some time in between each one. If the generator faults with all the breakers off you are looking for a short circuit type problem. If the power comes up OK that way then it's probably a delay issue.

I'd also talk to the folks who did your generator. They should be able to tell you if the delay is mostly in the generator or not. There should be a specification for them if it is the generator control board holding the field off until the motor stabilizes. They should be able to tell you if they tested that delay. It's something easy to overlook if they started with no load then plugged in or turned on the test load. Depending on where I was in my career I might have done it either way. Be nice about what happened but you really should understand how they tested it. If you do learn it was a generator delay issue share that knowledge back in a nice way. A lot of that tribal knowledge has been lost in the way they train folks today.

I could be wrong but I think most of the delay is in the generator not the transfer switch. If I was designing the system I would have it that way. The internal combustion engine takes a bit of time to stabilize it's speed so the frequency will be within limits. That dictates giving the generator control board the long delay while it senses speed or frequency. Once that stabilizes the transfer switch only needs a short delay to make sure it has a solid input to switch to. A few tenths of a second would do it.

That is the kind of esoteric knowledge you will need to find what is really going on. Welcome to the world of technicians... ;-)

[Eric1959]

UPDATE:

Took my transfer switch box out to examine it better.

I see no burnt areas at all. I know this model box is obsolete tho.

[twinboat]

Now remove the red and black wires that come from the generator. Wrap a bit of tape around them and start the generator.

If the generator breaker still kills the generator, it's the wire going back to the generator.

[Eric1959]

Ok, did that. Gen still shut down with both breakers on.

Then, as shown in the one pic, I disconnected the cable from transfer switch to junction box where it tied into the cable going into the generator.

Started gen up, flipped bottom breaker on, ran fine, flipped top breaker on, gen shut down.

Tomorrow I will attempt to disconnect gray cable going into generator and see what I can do there. I can't pull generator out, it's tucked up into the body of the coach.

I'm also going to call Cummins, who looked at it 2 weeks ago, and ask them what wires/cables they disconnected to get the thing to work. As stated before, they said they hooked it up to their source, ran it at full load with both breakers on. They didn't pull the gen out tho.

[Eric1959]

Originally Posted by twinboat

Now remove the red and black wires that come from the generator. Wrap a bit of tape around them and start the generator.

If the generator breaker still kills the generator, it's the wire going back to the generator.

Called Cummins where we took RV. Asked the tech what he did to get it going. he actually disconnected all wires going to the start and both breakers, and hooked his own up to it. Ran fine. Told him what I did so far and it's somewhere in the cable harness between the generator and the junction box where it ties into the cables going to the transfer switch.

Today, I removed the breakers and switch. Began testing the wires in the harness.

Odd thing I thought to myself, I know I'm not stupid when it comes to basic electrical, but .. I put an ohm meter on the green "ground?" wire, then to one of the BLACK wires, it rang !.. did same to one of the white wires.. same thing, got connection.

So why would a ground wire, be tied to both the black (hot) and white (common) ??

[twinboat]

Because they are touching somewhere. Look for melted cable near exhaust pipes or crushed cable near slide rails.

[Eric1959]

After a bit more testing, I hooked a separate wire into the breaker where the black/yellow wire went. Touched other end of test lead to every wire exposed and got a hit on the meter.

Did this to the other solid black wire (both these wires "were" hooked to the breakers btw), then touched all wires again, nothing, unless I of course touched the solid black wire.

Hope that made sense, guess you had to be there .. anyways, I think somewhere, as you may suspect as well, the black/yellow wire has the short or is grounded somehow and causing the issues.

Thats the only wire that when on test lead, reads a signal if touched to every other wire exposed, which don't seem right.