Home » Public Forums » GMCnet » Another Lesson Learned the Hard Expensive Way (Not That Expensive, or Hard Maybe)
| Another Lesson Learned the Hard Expensive Way [message #315021] |
Wed, 22 March 2017 14:17  |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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So today I decided to tackle the self-appointed goal of reconnecting the Onan Voltage Regulator to charge the dedicated start battery (disconnected by a PO for unknown reason, maybe because he saw on GMCNet that is is a good idea, even though it is not for Onans with a dedicated start battery). For those not in the know, early models had a the dedicated start battery for the Onan instaed of using the house battery to start it. Disconnect the Voltage Regulator and the Onan will run down its dedicated battery after some hours of running, and then die.
So I was looking for the wire that ran from Pin 8 on the board to the VR. There was a wire on pin 8, and it ran towards the bottom front of the engine. There was another wire with one taped up end near the VR and it ran someplace towards the bottom front of the engine.
I wasn't smart enough to connect the dots until I had the front cover off the Onan and the flywheel cover and discovered I still couldn't see anything.
So I started thinking. Note to self, do the thinking before the working. This particular model has the splitter (for getting the flywheel alternator voltage to both the VR and the control board) AT THE FLYWHEEL ALTERNATOR instead of at the VR.
So I put the front of the Onan back together and connected the wire from the flywheel alternator to the correct AC pin on the VR and the loose ended wire from pin 5 on the board to the B+ pin on the VR.
Could have done that in seconds instead of ah hour or so. And I can return the $2.69 splitter that I bought at the auto parts store for a refund.
Has anyone else seen an Onan wired like that? 4k in a 1973 23' Sequoia.
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| Re: [GMCnet] Another Lesson Learned the Hard Expensive Way [message #315022 is a reply to message #315021] |
Wed, 22 March 2017 15:03  |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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On Wed, Mar 22, 2017 at 12:18 PM A. wrote:
> So today I decided to tackle the self-appointed goal of reconnecting the
> Onan Voltage Regulator to charge the dedicated start battery (disconnected
> by
> a PO for unknown reason, maybe because he saw on GMCNet that is is a good
> idea, even though it is not for Onans with a dedicated start battery). For
> those not in the know, early models had a the dedicated start battery for
> the Onan instaed of using the house battery to start it.
Why?
Onan. Flywheel is a known weak point that will fail
Disconnect the
> Voltage Regulator and the Onan will run down its dedicated battery after
> some hours of running, and then die.
>
> So I was looking for the wire that ran from Pin 8 on the board to the VR.
> There was a wire on pin 8, and it ran towards the bottom front of the
> engine. There was another wire with one taped up end near the VR and it
> ran someplace towards the bottom front of the engine.
>
> I wasn't smart enough to connect the dots until I had the front cover off
> the Onan and the flywheel cover and discovered I still couldn't see
> anything.
>
> So I started thinking. Note to self, do the thinking before the working.
> This particular model has the splitter (for getting the flywheel alternator
> voltage to both the VR and the control board) AT THE FLYWHEEL ALTERNATOR
> instead of at the VR.
>
> So I put the front of the Onan back together and connected the wire from
> the flywheel alternator to the correct AC pin on the VR and the loose ended
> wire from pin 5 on the board to the B+ pin on the VR.
>
> Could have done that in seconds instead of ah hour or so. And I can return
> the $2.69 splitter that I bought at the auto parts store for a refund.
>
> Has anyone else seen an Onan wired like that? 4k in a 1973 23' Sequoia.
> --
> 73 23' Sequoia 4 Sale
> 73 23' CanyonLands Parts Unit 4 Sale
> Upper Alabama
> "When I grow up I am going to be a curmudgeon."
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: Another Lesson Learned the Hard Expensive Way [message #315025 is a reply to message #315021] |
Wed, 22 March 2017 18:42 |
Dennis S
Messages: 3046
Registered: November 2005
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Have you read Ricks article?
http://www.gmceast.com/technical/Denney_GMC_Electrical_Sys.pdf
Dennis
A Hamilto wrote on Wed, 22 March 2017 14:17So today I decided to tackle the self-appointed goal of reconnecting the Onan Voltage Regulator to charge the dedicated start battery (disconnected by a PO for unknown reason, maybe because he saw on GMCNet that is is a good idea, even though it is not for Onans with a dedicated start battery). For those not in the know, early models had a the dedicated start battery for the Onan instaed of using the house battery to start it. Disconnect the Voltage Regulator and the Onan will run down its dedicated battery after some hours of running, and then die.
So I was looking for the wire that ran from Pin 8 on the board to the VR. There was a wire on pin 8, and it ran towards the bottom front of the engine. There was another wire with one taped up end near the VR and it ran someplace towards the bottom front of the engine.
I wasn't smart enough to connect the dots until I had the front cover off the Onan and the flywheel cover and discovered I still couldn't see anything.
So I started thinking. Note to self, do the thinking before the working. This particular model has the splitter (for getting the flywheel alternator voltage to both the VR and the control board) AT THE FLYWHEEL ALTERNATOR instead of at the VR.
So I put the front of the Onan back together and connected the wire from the flywheel alternator to the correct AC pin on the VR and the loose ended wire from pin 5 on the board to the B+ pin on the VR.
Could have done that in seconds instead of ah hour or so. And I can return the $2.69 splitter that I bought at the auto parts store for a refund.
Has anyone else seen an Onan wired like that? 4k in a 1973 23' Sequoia.
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Another Lesson Learned the Hard Expensive Way [message #315031 is a reply to message #315022] |
Wed, 22 March 2017 21:19 |
Jim Miller
Messages: 501
Registered: March 2008
Karma: 10
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On Mar 22, 2017, at 4:03 PM, gene Fisher wrote:
> Onan. Flywheel is a known weak point that will fail
Can you elaborate on why you say this?
Whether one uses it for charging a dedicated starting battery or not, the flywheel alternator must be present and functional in order for the control board to latch during the start sequence.
The flywheel alternator is dirt simple and I think it is one of the more reliable electrical items on the whole machine. We’ve worked on many Onans at the Miller Compound and not one bad flywheel alternator has been seen to date.
Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: [GMCnet] Another Lesson Learned the Hard Expensive Way [message #315033 is a reply to message #315031] |
Wed, 22 March 2017 21:56 |
Mr ERFisher
Messages: 7117
Registered: August 2005
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On Wed, Mar 22, 2017 at 7:20 PM Jim Miller wrote:
> On Mar 22, 2017, at 4:03 PM, gene Fisher wrote:
>
>> Onan. Flywheel is a known weak point that will fail
>
> Can you elaborate on why you say this?
yes
This is a more reliable answer, and cheaper
http://gmc49ers.blogspot.com/2015/09/onan-gmc-propane-conversion.html
The transformer is the cheap way to fix the broken alternator,
>
> Whether one uses it for charging a dedicated starting battery or not, the
> flywheel alternator must be present and functional in order for the control
> board to latch during the start sequence.
>
> The flywheel alternator is dirt simple and I think it is one of the more
> reliable electrical items on the whole machine. We’ve worked on many Onans
> at the Miller Compound and not one bad flywheel alternator has been seen to
> date.
>
>
> Jim Miller
> 1977 Eleganza
> 1977 Royale
> Hamilton, OH
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] Another Lesson Learned the Hard Expensive Way [message #315035 is a reply to message #315021] |
Thu, 23 March 2017 01:35 |
Richard Denney
Messages: 920
Registered: April 2010
Karma: 9
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Senior Member |
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I disconnected my regulator, and charge the Onan start battery from the
converter, which is always on when the Onan is running. I used a combiner
to keep the Onan starter from pulling start current from the house battery.
The ignition is powered by the battery.
I kept the same setup when I replaced my Onan with a Generac.
My Progressive Dynamics converter does a better job of tending the
generator start battery.
More here, including a schematic:
http://www.gmceast.com/technical/Denney_GMC_Electrical_Sys.pdf
Rick "been a while since I looked at that article" Denney
On Wed, Mar 22, 2017 at 2:17 PM A. wrote:
> So today I decided to tackle the self-appointed goal of reconnecting the
> Onan Voltage Regulator to charge the dedicated start battery (disconnected
> by
>
> a PO for unknown reason, maybe because he saw on GMCNet that is is a good
> idea, even though it is not for Onans with a dedicated start battery). For
>
> those not in the know, early models had a the dedicated start battery for
> the Onan instaed of using the house battery to start it. Disconnect the
>
> Voltage Regulator and the Onan will run down its dedicated battery after
> some hours of running, and then die.
>
>
>
> So I was looking for the wire that ran from Pin 8 on the board to the VR.
> There was a wire on pin 8, and it ran towards the bottom front of the
>
> engine. There was another wire with one taped up end near the VR and it
> ran someplace towards the bottom front of the engine.
>
>
>
> I wasn't smart enough to connect the dots until I had the front cover off
> the Onan and the flywheel cover and discovered I still couldn't see
>
> anything.
>
>
>
> So I started thinking. Note to self, do the thinking before the working.
> This particular model has the splitter (for getting the flywheel alternator
>
> voltage to both the VR and the control board) AT THE FLYWHEEL ALTERNATOR
> instead of at the VR.
>
>
>
> So I put the front of the Onan back together and connected the wire from
> the flywheel alternator to the correct AC pin on the VR and the loose ended
>
> wire from pin 5 on the board to the B+ pin on the VR.
>
>
>
> Could have done that in seconds instead of ah hour or so. And I can return
> the $2.69 splitter that I bought at the auto parts store for a refund.
>
>
>
> Has anyone else seen an Onan wired like that? 4k in a 1973 23' Sequoia.
>
> --
>
> 73 23' Sequoia 4 Sale
>
> 73 23' CanyonLands Parts Unit 4 Sale
>
> Upper Alabama
>
> "When I grow up I am going to be a curmudgeon."
>
>
>
> _______________________________________________
>
> GMCnet mailing list
>
> Unsubscribe or Change List Options:
>
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
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| Re: [GMCnet] Another Lesson Learned the Hard Expensive Way [message #315038 is a reply to message #315031] |
Thu, 23 March 2017 09:22 |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Jim Miller wrote on Wed, 22 March 2017 22:19On Mar 22, 2017, at 4:03 PM, gene Fisher wrote:
> Onan. Flywheel is a known weak point that will fail
Can you elaborate on why you say this?
Whether one uses it for charging a dedicated starting battery or not, the flywheel alternator must be present and functional in order for the control board to latch during the start sequence.
The flywheel alternator is dirt simple and I think it is one of the more reliable electrical items on the whole machine. We've worked on many Onans at the Miller Compound and not one bad flywheel alternator has been seen to date.
Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH
Jim,
I think Gene was thinking of the flywheel casting. Many have been cracked by having the fastener over tensioned(tightened).
I recently though I had found a bad flywheel alternator winding. A local owner could not keep his NH running. It would start just fine. I found no alternator signal at the board. So, I when to check the output at the alternator and there was no lead coming out of the alternator (that I could find). So, we openned up the alternator. The winding had been rotated 90° from any I have seen and the lead connected directly to another lead coming from the control board - WITH A SCOTCHLOK that had failed. (What a Surprise - NOT)
After an working jury repair and demonstration, we put it together with solder and heat shrink. w
I am havibng a bad time with GMCnet this morning.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Another Lesson Learned the Hard Expensive Way [message #315045 is a reply to message #315036] |
Thu, 23 March 2017 12:23 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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For Matt and others who wish to visit OKC whilst attending the Shawnee affair:
There are lots of interesting museums in OKC and vicinity. Not to be missed are the Murrah Bombing Memorial Museum just north of the memorial park in downtown OKC. The Kirkpatrick Museum and adjoining OKC Zoo in northeast OKC are a couple more goodies. There is a railroad museum just to the east of those two, plus a firefighters museum and American Softball museum in the same area. There is a tremendous art museum just to the west of the central business district.
If you are coming from the north, there is a tourist welcome facility just off I-35 where I-44/Turnpike toll road intersect. The same info is available just inside the OK borders of I-35 and I-40 coming from N/S or E/W. I believe all four of these welcome centers are now staffed by Native American tribes/nations that are in those areas.
There is also a tourist welcome center on SE 29th St (parallel to I-40) in Midwest City just east of OKC. Parking MIGHT be a strain for a GMC w/toad, but they have all the info there as well.
No particular GMC MH service places, but there are MANY RV dealers in the OKC area.
To ALL, welcome to Oklahoma Frontier Country!
I'm in the Black's List and my cell number is 405-642-7337 if I can be of assistance.
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ Since 30 November '53 ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ Member GMCMI and Classics ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ~ TZE166V101966 ~ ~ ~ ~
~ ~ ~ '76 ex-Palm Beach ~ ~ ~
~~ k2gkk + hotmail dot com ~~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
______________
|[ ]~~~[][ ][]\
"--OO--[]---O-"
________________________________
From: Gmclist on behalf of Matt Colie
Sent: Thursday, March 23, 2017 08:46
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Another Lesson Learned the Hard Expensive Way
roy1 wrote on Thu, 23 March 2017 01:22
> I disconnect that regulator on my 76 because it wasn't needed but mostly because it was a source of a phantom drain on the battery.
Good Plan Roy,o
But a '76 Glenbrook has to be a 26 and can carry the house bank in the port rear corner. No 23 with an Onan has that option. We either have to make
the APU start battery work for us or install about 30' of welding cable. (It's only 20', but not an easy run and my rule is to always supply wire X 2
for any run in a sailboat, so I am being a little conservative here.)
Matt - Hold up in OKC - Its museum day
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Still Loving OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
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| Re: [GMCnet] Another Lesson Learned the Hard Expensive Way [message #315054 is a reply to message #315038] |
Thu, 23 March 2017 18:21 |
Jim Miller
Messages: 501
Registered: March 2008
Karma: 10
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On Mar 23, 2017, at 10:22 AM, Matt Colie wrote:
> I recently though I had found a bad flywheel alternator winding. A local owner could not keep his NH running. It would start just fine. I found no alternator signal at the board. So, I when to check the output at the alternator and there was no lead coming out of the alternator (that I could find). So, we openned up the alternator. The winding had been rotated 90° from any I have seen and the lead connected directly to another lead coming from the control board - WITH A SCOTCHLOK that had failed. (What a Surprise - NOT)
Oh yes, those scotchloks. Ugh.
I saw where someone suggested using a step-down doorbell transformer connected to the main generator in order to act as a surrogate signal in lieu of the flywheel alternator. That will sort of work - except when the generator has sat long enough that it has lost enough remanent magnetic field that it cannot begin self-excitation - and thus cannot provide a signal to the control board that the engine has achieved a successful start. This results of course in the classic “It starts and tries to run but immediately dies” behavior.
OTOH, the flywheel alternator being of permanent magnet design will never lose its ability to provide the desired signal to the control board.
Personally, I’ll stick with the flywheel alternator and if it ever breaks I’ll fix it! The alternator armature was used on many different onan models and should be available for eternity.
—Jim
Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: [GMCnet] Another Lesson Learned the Hard Expensive Way [message #315059 is a reply to message #315054] |
Fri, 24 March 2017 03:22 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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Noted
Tanks
On Thu, Mar 23, 2017 at 4:22 PM Jim Miller wrote:
> On Mar 23, 2017, at 10:22 AM, Matt Colie wrote:
>
>> I recently though I had found a bad flywheel alternator winding. A
> local owner could not keep his NH running. It would start just fine. I
> found no alternator signal at the board. So, I when to check the output at
> the alternator and there was no lead coming out of the alternator (that I
> could find). So, we openned up the alternator. The winding had been
> rotated 90° from any I have seen and the lead connected directly to another
> lead coming from the control board - WITH A SCOTCHLOK that had failed.
> (What a Surprise - NOT)
>
> Oh yes, those scotchloks. Ugh.
>
> I saw where someone suggested using a step-down doorbell transformer
> connected to the main generator in order to act as a surrogate signal in
> lieu of the flywheel alternator. That will sort of work - except when the
> generator has sat long enough that it has lost enough remanent magnetic
> field that it cannot begin self-excitation - and thus cannot provide a
> signal to the control board that the engine has achieved a successful
> start. This results of course in the classic “It starts and tries to run
> but immediately dies” behavior.
>
> OTOH, the flywheel alternator being of permanent magnet design will never
> lose its ability to provide the desired signal to the control board.
>
> Personally, I’ll stick with the flywheel alternator and if it ever breaks
> I’ll fix it! The alternator armature was used on many different onan models
> and should be available for eternity.
>
> —Jim
>
> Jim Miller
> 1977 Eleganza
> 1977 Royale
> Hamilton, OH
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
_______________________________________________
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