Onan and shore power questions

[Craigspeer2001]

I use my rv a lot for racing the other day before going racing it was hot so I decided to fire up front ac and let it cool off a bit before leaving, at this particular time I decided to fire up gen set as well , not knowing the rear air was on all of a sudden I here it fire up I'm like we'll that's cool keep in mind it's still plug on too shore power, wich on my model you have to do manual for gen set are shore power. So I decided to let it stay running like this and it cooled down real quick wich s nice in this south carolina heat.  What I want to know how is this possible and is my rear air wired directly to my gen set it's only a 5500 watt and will not run both ac anymore because I upgraded front ac to a 13,500 and back is still old 6500 btu. This is a great idea I had when I got to the track I plugged rv into my portable gen set fired up front air came on and ran great tried running house gen set at same time and rear air would not run soon as I get home unplugged coach from gen set left it running walk back inside front airs is on turned on back air it fired right up why want it do this off a portable gen set whats going on.

[Rickf1985]

Most of the time the AC is designed to only run one unit of you have a smaller size generator. Do you have any of the paperwork for the coach? If not contact Winnebago and they can get it for you. the users manual will have everything you need to know about using the AC,

[DaveVA78Chieftain]

Please understand that the 5K and larger generators have a 30 amp circuit and a 20 amp circuit.  The 30 amp circuit can only be connected to the Shore Power Cable (receptacle in Shore Power cable storage compartment).  The 20 amp circuit is only used to power the rear AC unit when the AC Select switch is set to Front (wired directly to the AC Select switch).

The key to this is the AC Select switch.
When AC Select switch is set to Front:
  1) the Front AC is powered from what ever is connected to the Shore Power Cable (Portable Gen, Campground Electric, or on board Onan Generator)
  2) The Rear AC is powered from the on board Onan Generator.

When AC Select switch is set to Rear:
  1) the Rear AC is powered from what ever is connected to the Shore Power Cable (Portable Gen, Campground Electric, or on board Onan Generator)
  2) The Front AC cannot be used.

[CapnDirk]

Thanks Dave.  My selector also says both.  I'm trying to fathom the info you posted.  Is this under the condition that the shore power would run one, and the genset the other?

[Craigspeer2001]

So I am right thinking that gen set is wired straight to selector switch the generator in the coach is a 5500 watt Onan. What gets is as long as I'm plugged into shore power I can run both ac with house gen raton running rear and shore power running front one, that if I'm at a track that has shore power most don't.   When I pull portable generator out of my trailer and plug into shore power receptacle the rear ac while no longer run off coach generator what's is the difference I want to be able to run both ac is all I'm trying to do the house generator will not run both it sounds like it's struggling and looses voltage when both are on ot drips to like 106 volts. My portable generator is 12000 watts it run both with no problem but don't no how to connect it to make it run both.

[Craigspeer2001]

Yes that what mine is doing shore power runs one and gen set rus rear air on shire power it want do it with my portable generator attached to shore power cable is what I'm trying to figure out.

[CapnDirk]

I would think then that you could make an adapter cord a foot or two long with female connecting to shore cable and male into the portable generator.


Dave will be along to correct/enhance our desire to burn something down.   

[DaveVA78Chieftain]

Onan Generator output 2 is wired to rear AC via the AC Selector switch
Onan Generator output 1 is connected via the shore Power cable.

Functional Drawing, does not reflect all 3 leads (hot, neutral, ground) that are controlled by the AC select switch.  Needed to prevent incorrectly cross connecting the 2 power sources.


There is a 3rd option installed on some RVs that does not require the on board generator to be operated.  The BOTH selection is a timer such that the front AC runs for say 15 minutes, turns off, then the rear unit turns on for 15 minutes, then turns off.  This front / Rear cycling is continuous.  It just has to turn off the running unit before starting the other unit

Without looking at your setup myself, I do not know why your portable generator is not powering the front AC when the shore power cable is connected to it.  I can only guess this is some sort of miss wire (e.g Hot - neutral or neutral- ground reversal).

There are websites that explain how to change your 30 amp setup to "steal" power for the 2nd AC by using the 15/20 amp receptacle in a campground post so you do not have to run your generator

Not advocating ths, just saying: You can get an adaptor to plug a 30 amp rig into a 50 amp campsite post (uses one side e.g. red/neutral/ground) however the RV AC power center main 30 amp breaker limits you to 30 amps.
50 amp to 2 30 amp RV connectors


50 amp to one 30 amp rv and one 20 amp connector


When changing from 30 amp to 50 amp service, all the AC input power cabling as well as the AC main breaker power center must be upgraded.  The power center I used in my converter upgrade could be wired either way.  Just like in house wiring, the loads on each side (L1 and L2) must be balanced as close as possible.

[CapnDirk]

Wow, I just thought it meant that if you had enough shore power it would run both. But you say that it switches?  I'm going to have to tear that old thing out of the wall and take a look.   


So if I understand, 30 amp shore line is not enough to run both AC?  but a say 5500 genset could?


As always, thanks Dave.


EDIT: with a 4k genset can the genset run the rear, and the shore power the front?  Still digesting your earlier post.


And my apologies to the OP for seeming to hijack his thread 

[DaveVA78Chieftain]

Onan BGE/NHE docs say:
4K generator supports 30 amps (1 30 amp output)
5K generator supports 40 amps (1 30 amp output / 1 10 amp output)
6K generator supports 50 amps (1 30 amp output / 1 20 amp output)

Onan BGM docs say:
5.5K generator supports 45 amps (1 30 amp output / 1 15 amp output that uses a 20 amp breaker)

The 5500 is right on the edge of dual AC support.  There is confusing information about how RV mfgs implemented some of this.  For example, 94 Winnebago brochure says they used 13.5K BTU AC, but post above implies he has 8.5 BTU AC.  Some Winnebago docs say you have to have a 6K gen to support AC but other documentation says the dual switch was installed for a 5.5K setup.  You simply have to check out what yours is capable of.

No, 30 amp service does not support dual AC operation.  That's why you have all the creative implementation approaches.

[CapnDirk]

Thank you very much Dave.  Gives me an idea of what to look for if/when I want to change out the genset.  First thing from what I read is to find out what BTU/amp units I have.  I know one has been replaced.


I think mine may have been modded.  You may remember I found an extra plug near the genset, and a switch spliced into the 110 line for AC next to the furnace.

[Craigspeer2001]

So this is all great info I'm glad you responded because I was almost had myself convinced that I could hook 240 volts to my shore power cable if I would have done that it would have fed voltage back thru my generator and burnt it up I'm sure glad I waited.I did find out something interesting today we had some down time I am comfortable setting I'm my rv with it 90 outside and about 68 in here with 2 generators running. I had my cable wired wrong on my portable generator and that was hooked to my shore power line know that I corrected that I'm able to run both ac one on my portable and the other rear ac on house gen set. I'm a happy for know but I'd love to be able to run both my ac units off shore power my portable generator is huge it run the whole rv if I could figure out how too wire it up.

[Rickf1985]

One question, Are you grounding your generator to the RV when powering the RV with it? There have been several cases of electrocutions or close to it from unbonded electrical connections. I don't know if this is causing your problem or not but if you have a miswired plug or circuit this will turn it up by blowing a breaker.

[Oz]

Not to worry about jumping into this topic, CapnDirk.  The OP hasn't been on since his last post.

I wouldn't spend any more brain time with the OP's issue unless he returns and chimes in first. But do feel free to continue with yours, if you wish.

[CapnDirk]

No worries.  Was a great thread thanks to Dave and I learned a lot about what I can and can not do with mine.


Seems to be many a person looking for an instant fix and even with several people here offering info, many don't go past two posts on a subject because they didn't get the instant fix.


But you probably don't see that often do you Mark?  In all the years.   


Maybe you could have a branch site of "Just Ask the Winnebago dudes".  Pay for the answer if you have to have it now, Mark gets a percentage for the site, we get a few bucks to supplement the SS.  "Call now!  A retired person is napping by to answer your questions"


I'm starting to see a pattern in my posts when my sugar is low.   

[Oz]

"Good things come to those who are willing to wait." 
As for what I've seen, the "wait" here on CWVRV is MUCH less than on many other communities.  Most questions are addressed in less than 24 hours and usually with several members offering their knowledge and experience. 


But... I'm getting  off topic!   D:oH!