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Peter_Crowl · 08-15-2022, 03:30 PM

2000 Bounder with Onan 5500 generator

Starting at the end: When performing required tests prior to installing a new regulator the tech reports:
manufacturer requests electrical testing prior to installation, performed test and did not get the desired results- pin 9 and 10 resistance is 0. Removed brush block to expose slip rings and rotor, tested for grounded rotor - ok tested for continuity on slip rings - none, open circuit in windings, generator will not produce electricity in this condition so I did not install the new voltage regulator.

So, I have a good running fairly low hour motor with a failed power plant. There are no RV salvage operations anywhere near me and it seems an unknown used Onan off Marketplace is +-$3,000.

Is this a repairable situation?

Has anybody managed to install a portable into the gen bay - thinking Predator?

As my late mother would say..what next?

Persistent · 08-16-2022, 07:05 AM

Sorry, I have no good info to answer your questions except the one about a portable Predator.

The internal combustion engines used in portable generators produces lots of carbon monoxide (CO). CO is deadly. It is odder less, colorless, and completely undetectable by human senses until it is too late to react. Victims fall asleep and never wake up. If it seeps into a closed space like an RV cabin, it will kill silently. Hopefully, the CO detector is working.

Locate the portable generator away from any habitation while it is running.

The Onan also produces copious CO. It was designed to be installed where it was. Even so, the owners manual cautions about CO getting in through cracks, windows, or other ingress places.

I wish you good luck and happy trails ahead!

Peter_Crowl · 08-16-2022, 07:23 AM

Actually the first issue for which I took it in was that it was running rich. Even with an extension stack you could smell it in the coach. Then it started "surging" so that was the final impetus.
They did the tune up and have it running properly but then found the voltage regulator to be burnt. And off we go.

donr103 · 08-16-2022, 08:25 AM

I would get 2nd opinion.. because you have not said that the service department cleaned up slip rings 1st.. before testing.. something smells bad.. and I just can't put my figures on it.. are you doing the work ? Are you willing to try? How many hours ?
Good luck and keep us posted

Peter_Crowl · 08-16-2022, 08:58 AM

Quote:

Originally Posted by donr103

I would get 2nd opinion.. because you have not said that the service department cleaned up slip rings 1st.. before testing.. something smells bad.. and I just can't put my figures on it.. are you doing the work ? Are you willing to try? How many hours ?
Good luck and keep us posted

I'll be picking up the coach later this morning and will ask questions. For now this is what I have "...the manufacturer requests electrical testing prior to installation, performed test and did not get the desired results- pin 9 and 10 resistance is 0. Removed brush block to expose slip rings and rotor, tested for grounded rotor - ok tested for continuity on slip rings - none, open circuit in windings, generator will not produce electricity in this condition so I did not install the new voltage regulator." The tech is said to be "Onan Certified" and the shop has a good reputation so I'm inclined to think it's a legit issue.

randomledder · 08-16-2022, 10:30 AM

At one time the slip rings could be replaced. The slip rings connect to the rotor windings, I would be curious if they checked the rotor resistance at the wires. I seen one have a bad connection from the wire tor to the slip ring block years ago. Maybe I’m missing some but have you checked into replacing just the rotor if it’s bad?

donr103 · 08-16-2022, 10:33 AM

You can throw in the towel.. I am not in any way.. impuning the reputation of the shop.. you sound like you are not interested in doing your own work.. I respect that..
Good luck and keep us posted

mfire1339 · 08-16-2022, 10:46 AM

I didn't think they would keep running if not making power.

Mike

spyderRV · 08-16-2022, 10:53 AM

[QUOTE=the manufacturer requests electrical testing prior to installation, performed test and did not get the desired results- pin 9 and 10 resistance is 0. Removed brush block to expose slip rings and rotor, tested for grounded rotor - ok tested for continuity on slip rings - none, open circuit in windings, generator will not produce electricity in this condition so I did not install the new voltage regulator." The tech is said to be "Onan Certified" and the shop has a good reputation so I'm inclined to think it's a legit issue.[/QUOTE]

pin 9 and 10 resistance is 0 or should be 0? If the rotor winding is good and the brushes and wiring are good I would expect that ohm measurement to be low. If the rotor is truly open, than the resistance measurement should not be zero. It too should look open.

If it were mine I would pull it apart and try to find out why the rotor's winding is open. Might be a simple fix.

Talloaks · 08-16-2022, 12:02 PM

Two points:

People do try to install portable generators in their RV's. It's not a good idea, for the reasons already mentioned as well as others. Portable generators are not certified for RV use, and are not compliant with NEC code for onboard RV generator installations.

Sounds like you have a tech that is certified to work on Onan RV generators. I assume that is at an RV repair/service shop. Certification notwithstanding, they might get a handful of these types of cases in a year's time. You might want to check on a motor/generator rewind specialty shop in your area. They do nothing but this type of work, and their shop rates will almost certainly be cheaper than an RV shop.

Peter_Crowl · 08-16-2022, 03:27 PM

Well it seems the generator part of the unit is out. It would need a new rotor which would seem to be +-$900 and at the same time unavailable.
Now I need to figure out how I can mount a Predator 8750 in that bay.

spyderRV · 08-17-2022, 07:04 AM

I looked up the specs of the Predator 8750. My math says it will use 9.6 gallons of gas running one air conditioner 24 hours. The 5500 will use the same amount with no load. The 5500 will use 14.4 gallons in 24 hours running 2 air conditioners.

Peter_Crowl · 08-17-2022, 07:55 AM

Quote:

Originally Posted by spyderRV

I looked up the specs of the Predator 8750. My math says it will use 9.6 gallons of gas running one air conditioner 24 hours. The 5500 will use the same amount with no load. The 5500 will use 14.4 gallons in 24 hours running 2 air conditioners.

Hadn't considered the fuel consumption aspect of one vs the other so thanks for that.

The 5500 wasn't sufficient for running two at once though so there was the "shed" system that alternated between front and rear...so there's that.

Random thoughts with the understanding that spending +-$3,500 for a new Onan is not an option:

While the 8750 is an inverter generator it isn't enclosed so it's going to be more noisy especially when running in a closed bay.

Will it cool sufficiently in a closed bay?

Looking at how we would be using the generator it's apparent that the primary task is running the air conditioners while going down the road. It gets mighty warm in the coach on a summer day in South Alabama. We're not "boondockers" unless it's an occasional overnight on the way to a spot with hook-ups. So therefore might the 8750 be overkill?

That said our main reason for buying the coach is as a Hurricane Escape Pod and to be used if necessary as a temporary residence in the event storm damage prevents us from living in our house. In that case the generator would serve alongside our Predator 3500 in powering various appliances.

Lots to consider.

spyderRV · 08-17-2022, 09:39 AM

"The 5500 wasn't sufficient for running two at once though so there was the "shed" system that alternated between front and rear...so there's that."

Obviously I don't know what air conditioners you have, but if I put the fridge and water heater on propane I can run both of my AC's at once with the same generator, no shedding.