Battery bank wiring for a 73

LQQKatJon

LQQKatJon

Well-known member
Oct 22, 2010
3,210
530
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St. Cloud, Mn
lqqkatjon.blogspot.com
I am assisting with some work on a pretty stock 73 GMC sequia. I had the owner go out and buy a ragusa sliding battery tray, because when we
originally took a quick look at it, I noticed there was no rear battery, and he was complaining the interior systems were not working, and his gen
light was on. I just figured someone had removed the house batteries.

now that I was able to spend a weekend with the coach, I have figured out(or remembered) that 73 has the house battery up front, and in the back
they just have a battery for the onan.

So I have everything now back hooked up properly- stock. He had 2 new batteries for the front, a nice starting battery and a nice 12v deep cycle
marine/RV for the house. Isolator is working and I installed a combiner.

so the question is, we have a nice ragusa sliding battery tray by the onan, now. and think it should be filled up with batteries.

How would one suggest the best way to do that? just install it with a shut off/switch. the question I am getting at, is as I understand we would
not want to tie it in parallel with the 12v marine/deep cycle up front and make it just 1 larger battery bank because they might drain each other or
melt down in a cell failure?

how have others done theirs?

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
I can't imagine it would be to much different than a boat.

Sometimes we have house batteries on opposite ends of the boat, tied together by 2/O cable typically.

Nothing in the GMC MH has the amp draw that something like a bow thruster in a boat would have, so you should be able to get by with a 4awg positive
cable and tie the negative directly to the frame.

Jared
--
Jared & Tina Lazaron + 7yr old Daughter.

77 Eleganza II "Recherché" Winterfeldt 455, Holley ProJection, Doug Thorley Headers, 3in exhaust, Switch Pitch, Alcoas, ONAN 6.5 Emerald series, CMC
Restoration

GO SEAHAWKS!!

Arlington, WA 98223
 
> I am assisting with some work on a pretty stock 73 GMC sequia. I had the owner go out and buy a ragusa sliding battery tray, because when we
> originally took a quick look at it, I noticed there was no rear battery, and he was complaining the interior systems were not working, and his gen
> light was on. I just figured someone had removed the house batteries.
>
> now that I was able to spend a weekend with the coach, I have figured out(or remembered) that 73 has the house battery up front, and in the
> back they just have a battery for the onan.
>
> So I have everything now back hooked up properly- stock. He had 2 new batteries for the front, a nice starting battery and a nice 12v deep
> cycle marine/RV for the house. Isolator is working and I installed a combiner.
>
> so the question is, we have a nice ragusa sliding battery tray by the onan, now. and think it should be filled up with batteries.
>
> How would one suggest the best way to do that? just install it with a shut off/switch. the question I am getting at, is as I understand we
> would not want to tie it in parallel with the 12v marine/deep cycle up front and make it just 1 larger battery bank because they might drain each
> other or melt down in a cell failure?
>
> how have others done theirs?

Jon,

I did not have any choice as the 23s don't have the space near the APU for batteries. If you do as you have described, and you do little else, he
will not get in trouble right away. There is a distinct problem with the original wiring. There is only a #10SAE cable to the rear. That will serve
as a sort of as a current limiter to prevent any likely disaster. It will also limit the charge rate av available to to recover the house bank.
There was a battery in the rear to crank the APU and do nothing else, but you can connect from there to the DC distribution panel that is nearby and
use the new house bank to crank as well. The thing that will not work is the battery boost will be just about worthless.
Having a pair of GC2s in the front is a monumental pain.
I bet this didn't answer all your questions, but I lost both may desktop and my laptop computers yesterday and I am working on recovery. If I don't
get back to you right away, please be patient.

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
 
Put a Blue Sea A/B mains switch on the house batteries. Only one gets used at a time for house power. No hard parallel. Put a $70 Yandina
combiner between the 2 batteries. Then the batteries are always independent and only parallel by #10 wire when charge Voltage is present. If one gets
low boondocking, switch to other. But both alway charge from Alternator via isolator or 125 to 12VDC convertor.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Jon

This link is to GMC East States tech article by Rick D
He shows 1973 coach set up with combiners.

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

> I am assisting with some work on a pretty stock 73 GMC sequia. I had the owner go out and buy a ragusa sliding battery tray, because when we
> originally took a quick look at it, I noticed there was no rear battery, and he was complaining the interior systems were not working, and his gen
> light was on. I just figured someone had removed the house batteries.
>
>
> now that I was able to spend a weekend with the coach, I have figured out(or remembered) that 73 has the house battery up front, and in the
> back they just have a battery for the onan.
>
> So I have everything now back hooked up properly- stock. He had 2 new batteries for the front, a nice starting battery and a nice 12v deep
> cycle marine/RV for the house. Isolator is working and I installed a combiner.
>
> so the question is, we have a nice ragusa sliding battery tray by the onan, now. and think it should be filled up with batteries.
>
> How would one suggest the best way to do that? just install it with a shut off/switch. the question I am getting at, is as I understand we
> would not want to tie it in parallel with the 12v marine/deep cycle up front and make it just 1 larger battery bank because they might drain each
> other or melt down in a cell failure?
>
> how have others done theirs?

--
Dennis S
73 Painted Desert 230
Memphis TN Metro
 
So I have a question in regards to the 1974 26', I only have a starting battery up front with a generator battery in the back. Not sure about my
wiring rats nest back by the Onan but, I am trying to repair that. Anyway. there is a circuit breaker up front as well as one in the back by the Onan
inside rear wall. Is it the same for the 26' 1974 that the house batteries are up front? I am in the process of running a new wire all the way front
to back with a 2/0 ( to handle existing and additional battery loads and a 1/0 for the battery in the rear and reconnect the Onan.

I know that most things in the coach are still factory so is there a simpleton wiring schematic on the 26'?
thanks


--
1974 GMC Sequoia 26'
 
wiring schematics are all on bdub's site.

I cannot really say what your 74 might be, but what you describe is common on most gmc upfit coaches like my 75 palm beach:

Back by the onan, there can be a round circuit breaker. as well as a solenoid. Up front, there should also be a solenoid.

ON those coaches, Starting battery is up by engine, and house batteries by onan. and there are a "boost solenoid" front and back, and a heavy awg
wire that goes from front battery, hits a terminal block by the "buzz box/converter" and then back to onan compartment.

the round circuit breaker normally protects the house wiring at 50 amps.

when you press the "boost" button on dash, it engergizes the front solenoid that connects both the starting battery to the heavy awg wire to the rear
battery, and engergizes the rear solenoid, that then creats a bypass of that 50 amp circuit breaker to allow more then 50 amps to go to the starting
battery to assist in engine cranking.

ONan wires come off the back of the onan drawer, and connect up to the house battery system direct.

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
to include the starter for the onan? so the house batteries in the back by the onan are the house batteries ( two 6 volt) as well as the starting
batteries for the Onan?
Thanks
--
1974 GMC Sequoia 26'
 
> to include the starter for the onan? so the house batteries in the back by the onan are the house batteries ( two 6 volt) as well as the starting
> batteries for the Onan?
>
> So if we wanted more "house" battery capacity where do we add them up front with additional wiring?
>
> Thanks

Grant,

It appears that what you have is a '74 set up like the later coaches, but without the heavy conductor and contactors for the start-boost circuit.
Except for the less effective boost capability, this is no issue.

There is a problem.....
If you want to increase the jar count in the house bank, it wants to be outside of the living area. (Lead/Acid batteries do not make good company.)
There are not many places in a TZE that this could be. I don't think you want to revert to a house bank in the right front corner. It is a bear.
The left front corner has your air pump.

What my real $uggestion??
Replace 19th century batteries with LiFePo4. These are expensive and updating the rest of the system will not be cheap either, but you can have
enough DC power to run the microwave and anything else. (The roof air will require a HUGE inverter.) Apart from buying the bank(s) for your demand,
you will want to replace the converter/charger to one calibrated for lithium to recover the bank from shore power or the APU, and a DC-DC charger
because the Lithiums charge at a higher potential than you main engine alternator likes.

Give me a couple of weeks and I can have a full proposal for you as I am working on that for a client right now.

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
 
So would these two batters be 12v? will there be a discharge issue? Yes I am looking that way and I want to add one or two solar panels to not onle
keep the house batteries charged but the starting battery as well. One of the reasons I am upgrading my boost wire to 2/0 from front o back. My boost
cable runs doen the frame rail and over the top of the radiator if that helps.
thanks
--
1974 GMC Sequoia 26'
 
> So would these two batters be 12v? will there be a discharge issue? Yes I am looking that way and I want to add one or two solar panels to not
> onle keep the house batteries charged but the starting battery as well. One of the reasons I am upgrading my boost wire to 2/0 from front o back. My
> boost cable runs doen the frame rail and over the top of the radiator if that helps.
> thanks

Grant,

If you are going with GC2s or Trojan T105, then you need 2. If you buy LiFePo4, buy the size voltage you want.

That is going to be a lot of money in copper. Be sure you protect it well. Either buy marine (fine stranded and tinned) or at least welding cable
(fine stranded and neophrene jacket.)

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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