House Battery Compartment Restoration

JSanford

JSanford

Well-known member
Sep 29, 2019
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Sacramento, CA
I am in the process of restoring my house battery compartment, and figured I would share my project.

The previous owner had MGM GMC install a sliding battery tray and two golf car batteries back in 2011. The batteries have died and need to be replaced so I am taking this opportunity to restore that battery compartment. MGM removed the original plywood floor and aluminum divider that goes between the battery compartment and the Onan. MGM installed a new thicker plywood floor and heavy duty sliding tray. Fortunately the PO saved the divider and the original battery hold down.

2x 100 AmpHr 6v golf car batteries in series, dated 5/11. The batteries charge up to 12+v but when you put a load on them the drop to 0. I asked on the FB group and consensus was after 9 years they are done.

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It is a nice tray, slides all the way out. I will will offer it up for sale here soon.

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MGM replaced the original 3/4" plywood with two 1/2" pieces screwed together, then attached it to the aluminum body from with a bunch of self tapping aluminum screws Very sturdy setup, but 3/4" was too tall for the original aluminum divider to mount to.

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Aluminum body structure seems to be holding up.

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Aluminum divider reinstalled. New 3/4" plywood floor painted black. The original floor was a solid piece of plywood that extended from the interior of the coach. Because the original had been cut off I had to secure the new "patch" floor using the screw holes that MGM had punched in the aluminum body frame when they installed the 1" floor.

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Waiting for special large flange rivets to arrive so I can fully secure aluminum partition to the generator compartment ceiling and walls.

Ordered professionally made cables for hooking up the new battery. The boost solenoid works, but a new one is cheap and would probably look 1000x better.

I have the dimensional drawings to build a new safety cover to enclose the battery compartment but am still hoping to find someone with an original sitting in their shed!

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Is there any reason you are getting rid of the sliding battery tray? I have the same tray and I like it. Its very convenient for working on the batteries.

I will rethink the battery installation when I goto LiFePO4 batteries.
 
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RF_Burns said:
Is there any reason you are getting rid of the sliding battery tray? I have the same tray and I like it. Its very convenient for working on the batteries.

I will rethink the battery installation when I goto LiFePO4 batteries.
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I can see how the sliding tray was a big convenience for the old style batteries. The golf car batteries are dead so I have to move on. The new Battle Born battery weighs a lot less than just one of the old style batteries and it does not require any maintenance.
 
Coming together.

Replaced most of the cables with custom made ones from BatteryCablesUSA nice quality with fast turnaround time. Replaced old magnetic switch, the old one worked fine but was rusty and crusty.
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Installed the shunt for the Victron battery monitor. Cut away a small section of insulation and used molly bolts through the fiberglass. Ran the data cable from the electrical cabinet along the heater ducts.

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Last edited:
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Jeremy, you are missing the + power wire for the Victron monitor. You likely know that, but just in case you are wondering why it wont work!
 
RF_Burns said:
Jeremy, you are missing the + power wire for the Victron monitor. You likely know that, but just in case you are wondering why it wont work!
Click to expand...

Yep, the little wires and the battery they go to are not in yet. :)

New Progressive Dynamics conv/charger should be here tomorrow, and a battery compartment cover is on its way from a kind GMCer in Michigan.
 
Jeremy, Will 2 of those BattleBorn batteries fit on the slide tray you have? I have the same slide tray and an all-electric fridge so I was planning on 2 LiFePO4 batteries.
 
Mike,

Sorry, you will have to talk to Battle Born about that, as far as I know they don't have any interface. Battle Born people are very friendly and more than happy to answer questions about their products if you call. Also, never order online, always call and they will give you discounts on everything below the internet price.

Bruce,

No, not the standard Battle Born Group 27 battery you usually see. The sliding battery tray fits two golf car batteries. Battle Born does make a 100ah 12v battery in the golf car size case but it is more expensive. The GMC house battery box will fit two regular group 27 Battle Born without the tray.
 
JSanford said:
Mike,

Sorry, you will have to talk to Battle Born about that, as far as I know they don't have any interface. Battle Born people are very friendly and more than happy to answer questions about their products if you call. Also, never order online, always call and they will give you discounts on everything below the internet price.

Bruce,

No, not the standard Battle Born Group 27 battery you usually see. The sliding battery tray fits two golf car batteries. Battle Born does make a 100ah 12v battery in the golf car size case but it is more expensive. The GMC house battery box will fit two regular group 27 Battle Born without the tray.
Click to expand...

Cool. I was just curious more than anything. I wasn't sure if there was an LED light on the case that gives you status.
 
And its pretty much done. Just need a small piece of foam pipe wrap for a 2" pipe to complete the 100% original look (not really needed since there are no battery gases anymore).

I was not happy with the hold down that came in the pile of extra parts with my GMC, it did not fit that Group 27 size Battle Born properly. I got a cheap plastic tray and hold down off the internet that had to be modified slightly, but is much better than the ill-fitting old one.
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The battery safety cover came from Jeff Rider, a kind GMCer in Michigan, who actually had two of them sitting in his garage. Without the cover you can see right into the battery compartment through the vents in the generator compartment door. I got a great deal on the battery, but it is still an expensive item to have sitting in plain sight. It is now pretty secure.
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If some future nut like me is doing this job and can't locate a battery safety cover, here are the dimensions that you could take to a blacksmith to have a reproduction made:

Battery compartment cover 060.webp
 
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Thats awesome.....the battery cover is a great touch and you probably have one of the few coaches that has it, as i suspect it was one of the first things removed when you owned one of these new.
 
Looks great, Jeremy.
I was looking for something else in my shop yesterday when found one I don't remember having. I plan to go to LiFePO4s as well, so I'll follow your lead.
Will 2 of those Battleborns fit in the space?
I do see that they have come up with a form facter to replace GC2s footprint exactly now, albeit a little taller and more expensive.
 
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bdub said:
Will 2 of those Battleborns fit in the space?
I do see that they have come up with a form facter to replace GC2s footprint exactly now, albeit a little taller and more expensive.
Click to expand...

Yes, 2 of the standard Battle Born group 27 size batteries will just barely fit upright end to end. Battle Born don't have to be sitting post side up, so you could actually stack several on their side, or pack them in on their ends.

I imagine most GMCers who have the GC2 x 2 sliding trays will probably just spend the extra money for the Battle Born GC2 version and keep their setups.
 
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