3 battery Isolator

D

dean hanson

New member
Apr 26, 2001
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My Avion has a rear battery used to start Conan the Onan. It also handles a
number of 12 volt items on the right side of the coach. Since I mostly dry
camp and do not run the Onan, any suggestions other that a new Isolator with
output for 3 batteries and a new wire run to the rear?



Dean C. Hanson75 Avion.

Fremont, Ca. 94536

(510) 657-9600

 
If you are going to place battery #3 near the second coach battery, you can use a diode mounted on a heat sink to provide the isolation. The battery charging voltage will be 0.7V lower (the diode drop). You live in an area that should have lots of surplus electronic stores with just what you need. I will give you a call later today.

>
>
> My Avion has a rear battery used to start Conan the Onan. It also handles a
> number of 12 volt items on the right side of the coach. Since I mostly dry
> camp and do not run the Onan, any suggestions other that a new Isolator with
> output for 3 batteries and a new wire run to the rear?
>
>
>
> Dean C. Hanson75 Avion.
>
> Fremont, Ca. 94536
>
> (510) 657-9600
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
I use a combiner for that purpose.

Rick “two combiner” Denney

On Tue, Oct 9, 2018 at 9:30 AM Dean Hanson
wrote:

> My Avion has a rear battery used to start Conan the Onan. It also handles a
> number of 12 volt items on the right side of the coach. Since I mostly dry
> camp and do not run the Onan, any suggestions other that a new Isolator
> with
> output for 3 batteries and a new wire run to the rear?
>
>
>
> Dean C. Hanson75 Avion.
>
> Fremont, Ca. 94536
>
> (510) 657-9600
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
 
I am also looking at redoing some wiring in my 73 and looking at a combiner
set up. In my set up, currently the engine and house are in the front and
the onan battery is in the rear, and I want to combine them all. Will I
need two combiners..one for the front two and a separate one for the rear.
I've read so many diagrams and it seems like they are all a little
different.

--
William D. Weyrowski
Midland, Michigan / Miami, Florida
73 Sequoia
 
I use two combiners.

http://www.gmcmhphotos.com/photos/g3677-electrical-wiring-concepts-for-2773-230.html

http://www.gmceast.com/technical/Denney_GMC_Electrical_Sys.pdf

Note that I charge the genset battery from the converter, not the
generator’s internal charger.

Rick “no voltage drop” Denney

On Tue, Oct 9, 2018 at 3:19 PM william weyrowski
wrote:

> I am also looking at redoing some wiring in my 73 and looking at a combiner
> set up. In my set up, currently the engine and house are in the front and
> the onan battery is in the rear, and I want to combine them all. Will I
> need two combiners..one for the front two and a separate one for the rear.
> I've read so many diagrams and it seems like they are all a little
> different.
>
> --
> William D. Weyrowski
> Midland, Michigan / Miami, Florida
> 73 Sequoia
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
 
I like the "Mouse Access Port"

How do you size that with the wire?

> I use two combiners.
>
> http://www.gmcmhphotos.com/photos/g3677-electrical-wiring-concepts-for-2773-230.html
>
> http://www.gmceast.com/technical/Denney_GMC_Electrical_Sys.pdf
>
> Note that I charge the genset battery from the converter, not the
> generator's internal charger.
>
> Rick "no voltage drop" Denney
>
> On Tue, Oct 9, 2018 at 3:19 PM william weyrowski

>
> > I am also looking at redoing some wiring in my 73 and looking at a combiner
> > set up. In my set up, currently the engine and house are in the front and
> > the onan battery is in the rear, and I want to combine them all. Will I
> > need two combiners..one for the front two and a separate one for the rear.
> > I've read so many diagrams and it seems like they are all a little
> > different.
> >
> > --
> > William D. Weyrowski
> > Midland, Michigan / Miami, Florida
> > 73 Sequoia
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> --
> Rick Denney
> 73 x-Glacier 230 "Jaws"
> Off-list email to rick at rickdenney dot com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

--
1977 Kingsley 455 as stock as it gets except lots of Ragusa parts
 
Dean,
You Need to download the following from bdub s website.

http://www.bdub.net/manuals/avion.pdf

Your comments are incorrect and not how the 12 VDC system works. You should have 2 batteries ( interior batteries )in the back and 2 in the front. The forward most battery is the chassis battery and the one just behind it is the front interior battery and is internal to the 12 VDC system.

You should read Page 5, para 5 called 12-volt system. It goes onto page 6 the entire first column. The Avion is a different animal on how it is wired. Look at the picture at the bottom of page 6 first column. You will see that the front and rear batteries are tied together on the lower part of diagram. You only need what came with the coach which was a standard 2 battery isolator. You should also look at page in the back reference area marked “12 Volt Wiring Diagram for 26’ Avion Interior. One side of the isolator charges the interior batteries and the other side charges the chassis battery.

The wiring diagram show that from the factory they had two 12 volt batteries in the rear (main battery supply) wired in parallel which is NOT the best of installation set up for battery longevity. I currently use two 6 VDC batteries in the back wired in series. The two gold cart batteries have been proven to be the best installation for the GMC motorhome. As I finish the coach rebuild, I will also change the front single 12VDC interior battery to two 6 VDC golf cart batteries and a good chassis battery. The two 6 VDC golf cart batteries and the single chassis battery will fit in the front area. I have done several installation in that configuration.

The 73 and 74 interior battery layout is different than the Avion which was produced only in 1975. The 73 & 74 had both the coach and chassis batteries in the right front. The battery in the back was for starting the Onan and was charged by the Onan. The 75 GMC produced coach had the more conventional layout with the chassis battery in the front and the coach battery in the back and that is what was produced in that config until the end of production.

You should review the wiring diagrams for the 75 and later GM built coaches tool They are available on the Bdub website.

J.R. Wright
GMC Great Laker MHC
GMCGL Tech Editor
GMC Eastern States Charter Member
GMCMI
78 GMC Buskirk 30’ Stretch
75 GMC Avion (Under Reconstruction)
Michigan
 
> I am also looking at redoing some wiring in my 73 and looking at a combiner set up. In my set up, currently the engine and house are in the front
> and the onan battery is in the rear, and I want to combine them all. Will I need two combiners..one for the front two and a separate one for the
> rear.
> I've read so many diagrams and it seems like they are all a little different.
>
> --
> William D. Weyrowski
> Midland, Michigan / Miami, Florida
> 73 Sequoia

William,

You have neglected to tell us if the coach is a 23 or 26.

Assuming it is a 26, move the house bank to the rear so you have one less battery to take care of. Get the full slide out tray and then you will be
in good shape.

I would like to write more, but we got back from Iowa, did the laundry and set out for New York and have just returned. I have a lot to do in the
next few days, but one is not to prep for the next excursion.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
Thanks Matt on the info and thanks for the previous email as well. Yes I
have already been contacted by several Michiganders, including John Wright
who just happens to live about 45 seconds away!

I plan on moving the house batteries to the rear, and am going through
wiring schemes before I ask any more questions. Want to have some idea of
what I am talking about before I ask for directions.

I will try and update my mods as they happen.

William Weyrowski
Midland, MI - Miami, Florida
73 Sequoia 26
 
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