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Old 09-20-2021, 10:20 AM   #1
NXR
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GT5 house batteries - anyone installed heavier ones?

Short story
I want to go from floating lead acid Group 27 house batteries to AGM Group 31 batteries but it will add another 30 pounds to the battery compartment.


Long story
Our house batteries, two 12 volt floating lead acid Group 27 no-namer's, have always been weak and finally flamed out. If I got an hour or two out of them before hitting 12.0 volts (with the inverter off and just the LED lights on) they were having good day. With the inverter on they usually were at 12.2 or 12.3 volts within five minutes.

I came off shore power after a few weeks and started the generator about fifteen minutes later, or rather tried to start the generator. The generator cranked for about four seconds and stopped. I walked inside and looked at the voltmeter and it was 12.0 volts. The house batteries used to drop to 11.6 to 11.8 volts when starting the generator immediately after coming off shore power so it's past time and winter is coming. They're only two years old but whatever.

The existing batteries are just under 50 pounds each and I'm looking at an AutoZone Duralast Group 31 AGM but they weigh about 65 pounds each.

So I'm looking at 130 pounds of batteries in that GT5 compartment to the left of the entry door instead of 100 pounds.

https://www.autozone.com/miscellaneo...ry/1006725_0_0

I'm tired of cleaning and checking these things so I definitely am going AGM for this change. Yes, I looked at the Flow-Rite system. Two Group 27 FLA batteries + the Flow-Rite system for 12 cells + the Flow-Rite hand pump comes to about $300 versus $400. I am willing to pay $100 to just stop messing with those things multiple times a year.

I know the GT7 has four batteries and I think they're in the same compartment because the hydraulic pump and components got moved to the propane tank compartment. So if FR is using the same welded metal compartment construction (same gauge metal and same welded attach points) for the GT5 as they do for the GT7 the compartment should handle another 30 pounds easily. But I do not know if it is the same compartment construction.

The GT5 battery/hydraulic compartment is 20" deep x 27.5" tall x 27.5" wide and welded in several places.

So...has anyone installed heavier house batteries in a GT5 and if so, what weight and how long ago. ? I am not interested in lithium at all and I would like somewhat larger capacity batteries.

This Duralast AGM31 is the lightest ones I've found. Others are about ten pounds more so I do need to positively confirm their weight.

If you have an AGM alternative I'd certainly be interested in hearing about it.

Thanks,

Ray
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Old 09-21-2021, 10:08 AM   #2
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Batteries

Hello, I've been wondering the same thing about the battery box. Hopefully someone chimes in with some good info.
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Old 09-21-2021, 11:03 AM   #3
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I’m pondering a similar change.

Backstory: My original coach batteries were garbage after a few trips, so I bought replacements at Costco. They were better but I still had issues with them maintaining a charge. Then when rig was in for unrelated warranty work the batteries were as bad as originals. The proprietor left battery disconnect turned on while rig was in their care, months. So, I went back to Costco and they replaced batteries, no charge. They did make it clear that is a one time policy.

So, I have paid closer attention to batteries, charge state, etc and gathered some data. I came to conclusion that the disconnect switch only isolates “some” systems and not all. I noted there are three wires that connect to one of the battery’s positive terminals, separate from the cable that goes to a menagerie of stuff in a electronic box. I concluded this is where the solinoid (or?) that is consoled by disconnect switch by doorway steps.

So, this means that although the majority of coach subsystems are isolated {disconnected) from batteries vis this switch, there remain three wires (going to something, if I could get a copy of schematic this would certainly help understanding) that are still connected and therefore a potential draw.

I decided the only to ensure that there is no potential for a draw on coach batteries was to install a ground isolation switch. This has eliminated to draw down of battery state. However I have yet to go on any trips to determine if batteries perform any better or whether I still need to upgrade.
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Old 09-21-2021, 11:44 AM   #4
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AGM is definitely the way to go. The LiFPO are great but unless you will be noon docking extensively the upfront price isn’t worth it.
I would fit as many as you can in there. The welds and brackets should be able to handle the weight of 2 batteries. If you have room for a 3rd I would add one.
That’s what I plan on doing with mine. I have flooded now. When they are done I will also go with 3 group 27 AGMs. As you stated, no need to check them and they are far more stable in an RV than the flooded batteries. With all the vibration going down the road that’s a plus. And realistically AGM are not much more than flooded. But I would go with cheapy from Dursley from Autozone. I would at least go with Napa. Maybe even go with 2 6V golf cart batteries in series?
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Old 09-21-2021, 02:41 PM   #5
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Quote:
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This Duralast AGM31 is the lightest ones I've found. Others are about ten pounds more so I do need to positively confirm their weight.

Ray
The dense material in an AGM battery, responsible for most of the weight, is the lead plates, same as in a Flooded Lead Acid battery. The other material is the glass mat. If you are picking batteries by lightest weight, you would be picking the battery with the shortest life.
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Old 09-21-2021, 03:43 PM   #6
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I bought the Duralast AGM31's today but have not yet installed them. I had to clean and paint the compartment first and the paint is still drying.

The battery box has several welds to the frame so I think it will be OK. That uncertainty is one reason I went for the lightest. Guesstimating the weight of the hydraulic stuff in the same compartment it looks like I'm adding about 20% more weight.

I had saved some posts from people who installed golf cart batteries, which I was also interested in due to their much higher reserve capacity and the ability to discharge them to 20% versus the usual 50%. The golf cart batteries weighed between 65 and 67 pounds each.

They also were a whole lot more expensive and we really do not run on just batteries. I also was unsure how golf cart batteries would do for starting the Onan 5500 generator or the V10 if needed in an emergency. It looks like the Onan starter uses less than 100 amps so golf cart batteries should be OK but I dunno for certain since we only have room for two batteries.

I only found one battery, a West Marine, of equivalent capacity that had a warranty longer than 1 year. It has an 18 month warranty and is over $100 more expensive per battery.

The originals were fully charged (for over a week) so I cut shore power. With the inverter on and drawing about 3 amps plus the interior LED lights, the original batteries went from 12.9 VDC one minute after shore power was cut to 12.1 VDC in thirty minutes.

I looked at Napa but they seem to only have one marine dual purpose battery in AGM, it has the wrong terminals, Reserve Capacity is 175 versus 200, and it was $300. But it was four pounds lighter.

https://www.napaonline.com/en/p/BATE...ressionRank=24

As soon as I tear the molded caps off the AGM31's I'm committed.

Fingers crossed,

Ray
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Old 09-21-2021, 04:46 PM   #7
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OK, they're in and the Group 31's easily fit as I expected. The compartment felt solid when one end of the batteries may have dropped a bit into place.

Shore power is on so they're charging and we'll see how they do soon. We're supposed to get a lot of rain tomorrow so it may not be until after that.

This better make a big, positive difference.

Ray
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Old 09-21-2021, 05:00 PM   #8
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Price comparison

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I had saved some posts from people who installed golf cart batteries, which I was also interested in due to their much higher reserve capacity and the ability to discharge them to 20% versus the usual 50%. The golf cart batteries weighed between 65 and 67 pounds each.

Ray
For a price comparison, I bought six Interstate GC-2 golf cart batteries for...the golf cart (what else?) at Costco a couple of months ago. They were $89 each.
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Old 09-21-2021, 05:13 PM   #9
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For a price comparison, I bought six Interstate GC-2 golf cart batteries for...the golf cart (what else?) at Costco a couple of months ago. They were $89 each.
Yep, it's a capacity thing for me. I'd need two that can do the work of six and those ain't $89...

Ray
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Old 09-21-2021, 05:50 PM   #10
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Looks good! Have you considered adding a rubber isolator/washer between the battery hold down strap and wingnut/washer. I was thinking it would provide a little relief on the top of the battery when going down the road. Just wondering if it's necessary or not
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Old 09-21-2021, 06:17 PM   #11
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Quote:
Originally Posted by JoePK
Looks good! Have you considered adding a rubber isolator/washer between the battery hold down strap and wingnut/washer. I was thinking it would provide a little relief on the top of the battery when going down the road. Just wondering if it's necessary or not
I don't think it needs vibration protection but it could help keep the batteries from sliding under the hold-down. Thanks for the suggestion.

Ray
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Old 09-23-2021, 12:26 PM   #12
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After looking over the AGM battery installation multiple times I realized I had a potential problem.

The batteries are held in place by a solid metal "strap" that runs across the center of the batteries. Unlike the original flooded lead acid batteries that have caps sticking up on either side of the hold-down strap, the tops of the AGM batteries are completely flat. That means, if the battery hold-down strap loosens up, the batteries could slide inward or outward.

There is 3" from the hold-down strap to either a positive or negative battery post but there is about 4" from the ends of a battery to the compartment wall.

So if a battery slid inward there is a chance that the metal hold-down strap could contact a positive battery post and cause one heck of a fire, very rapidly...

To reduce the possibility of this happening I took some plastic spiral wrap (anti-chafe for wiring) and wrapped it around the hold-down strap. I then took some plastic wiring loom and put it over the spiral wrap.

While this "should" keep a dead short from occurring if a battery slides inward, I'm thinking I'm also going to paint a 2x4 black and secure it between the batteries and the compartment inside wall to limit the amount the battery can slide.

The movement of the batteries outward should be limited by the length of the heavy gauge battery cables but I see no reason to not secure a 2x4 on the other side of the batteries.

Our first trip is a ways off so I've got some time to think this through more. If someone has another suggestion please feel free to offer it.

Ray
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Old 09-23-2021, 12:35 PM   #13
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The new, somewhat larger capacity house batteries that actually work will cause an unintended issue with the doggie.

Our Precision Plex Automatic Generator Start (AGS) function will only trigger on "low house battery voltage", not "interior temperature too high". I currently have the AGS set to start when the house batteries drop to 12.0 VDC.

The issue is what can happen if the campground power goes off on a hot day for an extended period of time while we are away and the doggie is inside: no air conditioning.

While we do have a wireless (cellular) temperature alarm to warn us of this condition, we could be a few hours away, out on the water, on a tour, or something else like no or weak cellular service. Or the alarm vendor is down. Etc.

I can't think of a technological fix for this problem, especially since we turn lights and other stuff off while we're gone The only possibility might be to raise the AGS "low house battery voltage so start the generator" from 12.0 VDC to something like 12.4 VDC.

Again, any suggestions are appreciated.

Ray
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Old 09-23-2021, 05:30 PM   #14
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New battery tests

Started at 12.6 VDC - Turned shore power off. The inverter is on and the usual interior lights are on. Current draw is about 7.5 amps.

One hour: 12.5 VDC

Two hours: 12.5 VDC. I turned the main living area TV on and the voltage dropped to 12.4 VDC. The current draw is now 11.5 amps.

Three hours: 12.4 VDC

Four hours: 12.3 VDC

Five hours: 12.25 VDC

Six hours: 12.25 VDC

Seven hours: 12.15 VDC

Eight hours: 12.1 VDC and then I turned shore power on.

Yeah, this is just a little different from the original batteries.

Ray
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Old 09-23-2021, 06:00 PM   #15
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Batteries

The wood idea sounds like a good idea. I would put some industrial strength Velcro on the edges to keep them from moving around. That way they're removable too. The voltage test looks good. I would like to know how they perform with the a couple of lights on, and the TV and movie playing. That would give me comparison of how my old ones are performing.
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Old 09-23-2021, 06:32 PM   #16
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Originally Posted by JoePK
The wood idea sounds like a good idea. I would put some industrial strength Velcro on the edges to keep them from moving around. That way they're removable too.
Good thought, thanks. I did not want to screw the 2x4's in from underneath.

Quote:
I would like to know how they perform with the a couple of lights on, and the TV and movie playing. That would give me comparison of how my old ones are performing.
That was the last six hours. The 40" Summit TV and sound bar were on and playing a channel, whatever was on. All interior ceiling lights except the bathrooms and the bedroom were turned on for the entire test.

Ray
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Old 09-23-2021, 06:38 PM   #17
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Batteries

That's pretty impressive they stayed above 12V with all that on. It's a lot better than mine currently. My batteries have degraded, but still not enough to replace yet. I'm pretty sure next year I'll be going through the battery change out. Thanks for the info
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