| One Wire Alternator [message #195433] |
Sat, 12 January 2013 22:27  |
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SteveW
Messages: 538
Registered: June 2005
Location: Southern California - Ora...
Karma: 1
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Senior Member |
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Greetings again from the new guy...
Among other things that I'm still figuring out on my new coach - I started to chase my intermittently glowing alternator light.
I purchased an APC a while ago - and attempted an install today.
Simple - right ??
Almost. I discovered that I have a "one wire alternator" so no remote voltage sensing...
The alternator part number is Bosch 0120 469 644 645. The label also indicates 80A. Our friends at google tell me that this is a SAAB OEM part number. Makes sense, as the previous owner was a SAAB test driver.
The coach also has a voltmeter that reads above 12 volts - maybe 13 (it's an analog dial) when the engine is running. Oddly though - it doesn't register any voltage at all for the first few minutes of engine running. I haven't yet chased the connecting wires to see where it's reading voltage.
So... I'm seeking advice from the brain trust:
Shall I just live with the glowing alternator light??
Do I still have the failing nichrome wire danger??
Shall I replace it with a proper voltage sensing alternator ??
As always, thanks in advance for this incredible collection of expertise and y'alls willingness to help the new guys.
Steve W
Southern California
1973 23'
Steve W
1973 : 23'
Southern California
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| Re: One Wire Alternator [message #195435 is a reply to message #195433] |
Sat, 12 January 2013 23:07  |
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SteveW
Messages: 538
Registered: June 2005
Location: Southern California - Ora...
Karma: 1
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Senior Member |
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A little more detail:
The cable assembly going to the alternator has three wires: RED, BROWN, and WHITE.
The RED is 12 guage (maybe 10), The BROWN is 16 guage, and the WHITE is 12 guage.
RED and BROWN are connected. WHITE is open.
It looks like BROWN has been pulled from the two-wire connector and connected to a lug connector on the alternator.
I'm expecting that RED is output, BROWN is initial excitation, and WHITE is voltage sensing... correct ??
I suspect that it's the lack of voltage sensing that's making the gen lite glow - correct ??
The more I read - the less I know. Dang.
And... a photo to clarify my verbiage:
http://www.gmcmhphotos.com/photos/g6273-alternator-connections.html
SW
Steve W
1973 : 23'
Southern California
[Updated on: Sun, 13 January 2013 00:01] Report message to a moderator |
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| Re: [GMCnet] One Wire Alternator [message #195436 is a reply to message #195433] |
Sat, 12 January 2013 23:54 |
Tim Jeffries
Messages: 35
Registered: August 2012
Karma: 0
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Steve, I'm a new guy, too!
I'm in North SD County. Where are you?
I just upgraded all the battery cables to 2/0. Also found during that that
the Starter was hanging on by just a few wires. Went with the same $55
starter FYI -just in case that's the next "act".
I replaced the Alternator with an O'Reilly OEM also.
When doing this stuff I found this link from Gene:
http://gmcmotorhome.info/APC.html
for an Alternator Protection cable -along with some other valuable info.
(I'm not really the techie).
Have fun and good luck!
We should try to meet if you are nearby either here or my partner
shade-tree-mechanic-genius Rolando, who is in Riverside-Colton area.
Caio!
Tim
On Sat, Jan 12, 2013 at 8:27 PM, Steve Weinstock <steve.weinstock@cox.net>wrote:
>
>
> Greetings again from the new guy...
>
> Among other things that I'm still figuring out on my new coach - I started
> to chase my intermittently glowing alternator light.
>
> I purchased an APC a while ago - and attempted an install today.
>
> Simple - right ??
>
> Almost. I discovered that I have a "one wire alternator" so no remote
> voltage sensing...
>
> The alternator part number is Bosch 0120 469 644 645. The label also
> indicates 80A. Our friends at google tell me that this is a SAAB OEM part
> number. Makes sense, as the previous owner was a SAAB test driver.
>
> The coach also has a voltmeter that reads above 12 volts - maybe 13 (it's
> an analog dial) when the engine is running. Oddly though - it doesn't
> register any voltage at all for the first few minutes of engine running.
> I haven't yet chased the connecting wires to see where it's reading
> voltage.
>
> So... I'm seeking advice from the brain trust:
>
> Shall I just live with the glowing alternator light??
>
> Do I still have the failing nichrome wire danger??
>
> Shall I replace it with a proper voltage sensing alternator ??
>
> As always, thanks in advance for this incredible collection of expertise
> and y'alls willingness to help the new guys.
>
> Steve W
> Southern California
> 1973 23'
>
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Tim Jeffries
'73 260 -The Magic Bus
rePainted Desert
San Diego, CA
Park Host - San Diego County Park and Recreation
Hellhole Canyon Open Space Preserve
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| Re: One Wire Alternator [message #195437 is a reply to message #195433] |
Sun, 13 January 2013 00:03 |
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SteveW
Messages: 538
Registered: June 2005
Location: Southern California - Ora...
Karma: 1
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Senior Member |
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Tim - PM (Private Message) sent.
and got this reply:
You cannot send a private message to "Tim Jeffries", because this person is not accepting private messages.
You might want to update your profile and enable that feature...
SW
Steve W
1973 : 23'
Southern California
[Updated on: Sun, 13 January 2013 00:10] Report message to a moderator |
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| Re: [GMCnet] One Wire Alternator [message #195438 is a reply to message #195433] |
Sun, 13 January 2013 04:25 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Steve,
First, you need to go to www.bdub.net and download the manual for your '73
coach. It will contain the wiring diagram which will explain the wires you
describe (correctly except that the red is 10 gauge). No point in anyone
doing so here when that will do so much better a job and provide so much
more important information.
The glowing alternator light is a normal condition on early coaches which
was corrected on later ones and can be connected on yours by the simple
addition of a diode in the 20g brown wire connected to the instrument
cluster (cathode band away from the cluster). Check the chassis wiring
diagram for a '78 coach to see the diode in circuit.
If you still have an isolator, you DO need to re-install a remote sensing
alternator because the single wire alternator cannot correct for the 0.7
VDC forward voltage drop across the isolator diode to the chassis battery.
The batteries will never be fully charged. With a combiner installed the
remote sensing isn't quite a important but can still be beneficial because
it can compensate for line and connection voltage drops.
The single-wire alternator is probably not as likely to have the
catastrophic internal failure which causes the Nichrome wire catastrophe --
but I wouldn't want to risk it.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Sat, Jan 12, 2013 at 11:27 PM, Steve Weinstock wrote:
>
>
> Greetings again from the new guy...
>
> Among other things that I'm still figuring out on my new coach - I started
> to chase my intermittently glowing alternator light.
>
> I purchased an APC a while ago - and attempted an install today.
>
> Simple - right ??
>
> Almost. I discovered that I have a "one wire alternator" so no remote
> voltage sensing...
>
> The alternator part number is Bosch 0120 469 644 645. The label also
> indicates 80A. Our friends at google tell me that this is a SAAB OEM part
> number. Makes sense, as the previous owner was a SAAB test driver.
>
> The coach also has a voltmeter that reads above 12 volts - maybe 13 (it's
> an analog dial) when the engine is running. Oddly though - it doesn't
> register any voltage at all for the first few minutes of engine running.
> I haven't yet chased the connecting wires to see where it's reading
> voltage.
>
> So... I'm seeking advice from the brain trust:
>
> Shall I just live with the glowing alternator light??
>
> Do I still have the failing nichrome wire danger??
>
> Shall I replace it with a proper voltage sensing alternator ??
>
> As always, thanks in advance for this incredible collection of expertise
> and y'alls willingness to help the new guys.
>
> Steve W
> Southern California
> 1973 23'
>
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: One Wire Alternator [message #195453 is a reply to message #195433] |
Sun, 13 January 2013 14:24 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Now WHY is there a one wire alternator in there? Was the PO trying to make up for some bad wiring? And as Ken said it would have no way of "knowing" about the isolator voltage drop and though it would work in the short haul, the batts will be short lived.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: One Wire Alternator [message #195473 is a reply to message #195437] |
Sun, 13 January 2013 21:50 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| SteveW wrote on Sat, 12 January 2013 22:03 |
Tim - PM (Private Message) sent.
and got this reply:
You cannot send a private message to "Tim Jeffries", because this person is not accepting private messages.
You might want to update your profile and enable that feature...
SW
|
Steve,
If you look at the last of Tim's message you see the following:
This means that Tim accesses the "net" through GMCnet mailing list... not the on-line forum. So no private messaging. If you also used the list, you would have his email address. So there would be no need for private messaging, but is less secure.
Just some of the differences between the two systems. I find it amazing how well these different system work together... most do not realize how different they are!
As a note, most still use the email system, but that is slowly changing.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] One Wire Alternator [message #195474 is a reply to message #195455] |
Sun, 13 January 2013 21:55 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| comcast wrote on Sun, 13 January 2013 12:32 |
John,
Some GMC's came with a one wire alternator. Mine has the 150(?) amp monster that came with the engine out of a transporter.
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Just thinking...
A transporter wouldn't need a house battery so it wouldn't have an isolator. With no isolator, there wouldn't be the "need" for a remote sensing alternator and a single wire one would make sense.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] One Wire Alternator [message #195486 is a reply to message #195433] |
Mon, 14 January 2013 07:17 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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An old line engineer taught me years ago when we were fixing a directional antenna array which was 30 years old... first, set it back to its original condition. Then troubleshoot it. n It's much easier. And, if you've an isolator and two batteries, you >do< need a remote sensing alternator for best battery life.
--johnny
'76 23' transmode norris
'76 palm beach
From: Steve Weinstock <steve.weinstock@cox.net>
To: gmclist@temp.gmcnet.org
Sent: Saturday, January 12, 2013 11:27 PM
Subject: [GMCnet] One Wire Alternator
Greetings again from the new guy...
Among other things that I'm still figuring out on my new coach - I started to chase my intermittently glowing alternator light.
I purchased an APC a while ago - and attempted an install today.
Simple - right ??
Almost. I discovered that I have a "one wire alternator" so no remote voltage sensing...
The alternator part number is Bosch 0120 469 644 645. The label also indicates 80A. Our friends at google tell me that this is a SAAB OEM part number. Makes sense, as the previous owner was a SAAB test driver.
The coach also has a voltmeter that reads above 12 volts - maybe 13 (it's an analog dial) when the engine is running. Oddly though - it doesn't register any voltage at all for the first few minutes of engine running. I haven't yet chased the connecting wires to see where it's reading voltage.
So... I'm seeking advice from the brain trust:
Shall I just live with the glowing alternator light??
Do I still have the failing nichrome wire danger??
Shall I replace it with a proper voltage sensing alternator ??
As always, thanks in advance for this incredible collection of expertise and y'alls willingness to help the new guys.
Steve W
Southern California
1973 23'
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Unsubscribe or Change List Options:
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: One Wire Alternator [message #195538 is a reply to message #195433] |
Mon, 14 January 2013 16:21 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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I guess I learned something. I know the large frame 80a was from the cop package in the 70s. I didn't know there was a larger( truck sourced?) option but can see where an ambulance Transmode would need it.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] One Wire Alternator [message #195539 is a reply to message #195538] |
Mon, 14 January 2013 16:34 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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John, the delco remy 27 SI can be modified to produce 100 amps. I just had
one done for the coach I am working on. He replaced the single pulley with
a double one and replaced the stator windings as well as the rotor and
bearings along with the regulator and diode trio. $91.00.
Jim Hupy
Salem, Or
78 Gmc Royale 403
On Jan 14, 2013 2:21 PM, "John R. Lebetski" <gransport@aol.com> wrote:
>
>
> I guess I learned something. I know the large frame 80a was from the cop
> package in the 70s. I didn't know there was a larger( truck sourced?)
> option but can see where an ambulance Transmode would need it.
> --
> John Lebetski
> Chicago, IL
> 77 Eleganza II
> Source America First
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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