Another Lesson Learned the Hard Expensive Way

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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.
--
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."
 
> 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://bdub.net/gmcmotorhome.info/
Alternator Protection Cable
http://bdub.net/gmcmotorhome.info/APC.html
 
> Why?
> Onan. Flywheel is a known weak point that will fail
No. Its not. But the voltage regulator has been known to degrade and pull down the voltage to pin 8 on the board. Instances have occurred, but not
enough VRs are currently connected for anyone to know how often one fails.

Here's some extra data for "why".

House battery is up front.

Onan is in the rear.

Onan on these model years had a dedicated start battery and only a 10 gauge wire from the house battery (front) to the buzzbox (rear). So no large
cable from the front to the rear.

Either you make the OEM setup work, or run a 20' battery cable from the front battery tray to the Onan. Or you jump through hoops to put the house
battery in the rear and make that battery cable run to the front big enough to support the boost function.

Or you can connect the voltage regulator the way it came from Onan.

Which would you do?
--
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."
 
Have you read Ricks article?
http://www.gmceast.com/technical/Denney_GMC_Electrical_Sys.pdf

Dennis

> 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.

--
Dennis S
73 Painted Desert 230
Memphis TN Metro
 
A.

2.69$US for what splitter?? If you mean the thing to put 2es 1/4 I last bought both (parallel and stacked) for about 10$/c. (Of course, there is the
"need it now" penalty to be considered. But still.)

I have one BF in the coach and was gifted another. Both came to me with the correct connections.

By the by..... If you need a regulator. Get it on Ebay. Pay the extra 10$ for the similar package and check that it works when you get it. Not all
the cheap Chinese version will do well with a single sided input (that Onan uses and my Kohlers don't).

Matt
--
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
 
> 2.69$US for what splitter?? If you mean the thing to put 2es 1/4 I last bought both (parallel and stacked) for about 10$/c. (Of course, there is
> the "need it now" penalty to be considered. But still.) ...
There is some other stuff in the package that I don't need. I haven't opened it, so I can take it back. Or I can hold onto it in case I need it
sometime between now and death.

The instructions that everyone uses for disabling the voltage regulator shows that splitter at one of the AC spades of the regulator.

I got two wires running to the front of the generator. One is connected to pin 8 on the board and the end of the other was taped up and laying on top
of the generator along side the 120V circuit breaker.

After flailing around for about an hour (taking covers off and putting them back on), I just connected the wires.

I figure someone needed to mention this wiring difference so the next dim bulb can recognize what is right in front of him. I have been telling people
that a PO mucked with the wiring, but now I think all he did was disconnect the VR and tape up the connectors on the ends of the wires.

I don't know if it is a difference in model years, or between a 4k and a 6k, or some combination of both.
--
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."
 
> 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
 
> Have you read Ricks article?
> http://www.gmceast.com/technical/Denney_GMC_Electrical_Sys.pdf
>
> Dennis
No. I have considered a separate charger fed from the 120VAC to recharge the dedicated Onan start battery after a start and to compensate for the
current the Onan draws when it is running.

But it is WAY EASIER to use the existing Onan voltage regulator for its intended purpose. If/when it fails, simply replace it.
--
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."
 
>
> > 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://bdub.net/gmcmotorhome.info/
Alternator Protection Cable
http://bdub.net/gmcmotorhome.info/APC.html
 
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.
--
Roy Keen
Minden,NV
76 X Glenbrook
 
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

> 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
>
>
 
> 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
 
>
> > 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 - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Still Loving OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
> 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
That's a good idea when the Onan voltage regulator fails. Not much more expensive than replacing the regulator (maybe cheaper, OEM Onan is way
overpriced).
--
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."
 
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
Subject: Re: [GMCnet] Another Lesson Learned the Hard Expensive Way

> 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
 
> 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
 
Noted
Tanks

>
> > 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://bdub.net/gmcmotorhome.info/
Alternator Protection Cable
http://bdub.net/gmcmotorhome.info/APC.html
 
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