.EDIT: Regarding Question 2 below, the guys in the first few replies got me thinking I can suppress my OCD and get by adding water with a watering system when I would normally just inspect. If they're full, I'll know it because they won't take any water.The slide-out battery tray in this motorhome is designed for 3 group 27s. It currently has 2 new ones and a slightly older one that tests almost as new via they hydrometer. The tray can also probably fit 3 29s and maybe 3 31s. All with about 3/4" between them horizontally like so...______I_____I______I_____I______I_____IThe tray will also just fit 4 Deka GC2s in 2 vertical pairs thusly...___ ___I....I I....II....I I....II__I I__I___ ___I....I I....II....I I....II__I I__IEach pair might have 1/8" of gap between them, left to right. And maybe 1/2" between the top pair and the bottom pair.Also... the back vent caps are going to be very hard to check and fill without removing the front pair of 64 lb batteries... at chest level. There was a time when I could load an awkward, 120lb 4D in and out of a tight battery compartment solo, no problem, but... I guess I'm gettin' old.The benefit of the GC2s would be...1. 460 Ah vs roughly 3002. Greater deep cycling durability / longevity3. And easier to recover from progressive sulfation incurred by successive 50-90% charges.That's if the tray can stomach an extra hundred pounds or so.Questions:1. How bad would it be if the 4 Dekas were sandwiched together with no gap between them?2. How big of a boondocker does one have to be to remove a pair of GC2s every time one needs to check the electrolyte of the other pair? Let alone top them off....

I have four of those GC15s side by each touching, no issues. Agree 4 sixes is the better choice in the OP if they fit.You can make a chest- high platform even with the tray to use at home to move the batteries out to. You then have to move the back set out to the tray front where you can get at them.Only problem might be the 1/2" space not allowing for wires on the posts The load/charging pos or neg has to go on one of the bottom set's posts. That post also has the parallel link wire so it can be higher with crossing bent up wires. Add a fat inverter wire to the stack it gets higher.Perhaps rig post extensions that clear the caps and allow the wires to stay low. Short copper water pipe banged flat with holes in each end for extensions?Or is there another compartment that could be made into a battery compartment with a vented box like they do in 5er front cargo bays? Even if that only held 2 sixes, the two pairs don't have to be that close to work in parallel if there is wire routing.You could have just 2 sixes for 230AH if you can get by with that and more solar. You could have 2 sixes and one 29 and only have to do extra fuss with the one 29.

Sounds like more than I’d care to deal with. If you really want a bunch of reserve capacity, and plan on using it, might be money well spent to go lithium. Sealed lead acid is an option. No need to check water. There are 200ah 6v that are shorter than Trojan batteries. If you stacked them you wouldn’t need to touch them again. Mighty max batteries from Amazon. Worked well for me in space limitations.

My 4x GC2 were sandwiched for a decade with no issue. I had space to water but found it way better, easier, safer to get a watering system. If you were in SoCal I would give you the set up as I have converted to LFP.

If you are worried about topping up the water, you can add a battery watering system to make it easier.

BFL13 wrote:You could have just 2 sixes for 230AH if you can get by with that and more solar. You could have 2 sixes and one 29 and only have to do extra fuss with the one 29.Hey B,Thanks for weighing in.Yeah, you guessed it. I'm looking at the Duracell version of the Deka GC15s from Batteries Plus. They've agreed to honor the 10% online discount in-store. So just over $130 a piece.The house and Xantrex Freedom 458 have their own cables. So the Freedom will connect to the back pair and the coach to the front. Makes for easy isolation of one system from the other. And, of course there will be a couple of parallel cables between the 2 pairs.I barely have the height, but it's there... including cables. The problem is... the tray doesn't come out far enough. It's a bit of an issue even for the current 27s. I have to photograph the electrolyte of the battery furthest back with the iPhone in order to inspect. But it will be worse with the GC2s.Thanks to time2roll for the idea. I just ran across this. So maybe I could let go of my OCD and resign myself with being happy to just fill the cells on occasion and call it an inspection. Of course... after a long boondock sesh, I'll probably still want to dip the hydrometer.I have but 240W of portable solar panels, but the rig does have a killer generator and a 100A, 3-stage charger plus equalizing mode. Would be nice to sleep soundly with the heater running... knowing I have 230 Ah to play with before the bank hits 50%..

3 Group 27s with some wiggle room? Or 4 GC2 Sardines?

BFL13
Explorer II
Feb 25, 2022
I have four of those GC15s side by each touching, no issues. Agree 4 sixes is the better choice in the OP if they fit.

You can make a chest- high platform even with the tray to use at home to move the batteries out to. You then have to move the back set out to the tray front where you can get at them.

Only problem might be the 1/2" space not allowing for wires on the posts The load/charging pos or neg has to go on one of the bottom set's posts. That post also has the parallel link wire so it can be higher with crossing bent up wires. Add a fat inverter wire to the stack it gets higher.

Perhaps rig post extensions that clear the caps and allow the wires to stay low. Short copper water pipe banged flat with holes in each end for extensions?

Or is there another compartment that could be made into a battery compartment with a vented box like they do in 5er front cargo bays?
Even if that only held 2 sixes, the two pairs don't have to be that close to work in parallel if there is wire routing.

You could have just 2 sixes for 230AH if you can get by with that and more solar. You could have 2 sixes and one 29 and only have to do extra fuss with the one 29.
Grit_dog
Navigator
Feb 25, 2022
Sounds like more than I’d care to deal with.
If you really want a bunch of reserve capacity, and plan on using it, might be money well spent to go lithium.

Sealed lead acid is an option. No need to check water. There are 200ah 6v that are shorter than Trojan batteries. If you stacked them you wouldn’t need to touch them again.
Mighty max batteries from Amazon. Worked well for me in space limitations.
time2roll
Nomad
Feb 25, 2022
My 4x GC2 were sandwiched for a decade with no issue. I had space to water but found it way better, easier, safer to get a watering system. If you were in SoCal I would give you the set up as I have converted to LFP.
valhalla360
Navigator
Feb 25, 2022
If you are worried about topping up the water, you can add a battery watering system to make it easier.
KendallP
Explorer
Feb 25, 2022
BFL13 wrote:
You could have just 2 sixes for 230AH if you can get by with that and more solar. You could have 2 sixes and one 29 and only have to do extra fuss with the one 29.

Hey B,

Thanks for weighing in.

Yeah, you guessed it. I'm looking at the Duracell version of the Deka GC15s from Batteries Plus. They've agreed to honor the 10% online discount in-store. So just over $130 a piece.

The house and Xantrex Freedom 458 have their own cables. So the Freedom will connect to the back pair and the coach to the front. Makes for easy isolation of one system from the other. And, of course there will be a couple of parallel cables between the 2 pairs.

I barely have the height, but it's there... including cables. The problem is... the tray doesn't come out far enough. It's a bit of an issue even for the current 27s. I have to photograph the electrolyte of the battery furthest back with the iPhone in order to inspect. But it will be worse with the GC2s.

Thanks to time2roll for the idea. I just ran across this. So maybe I could let go of my OCD and resign myself with being happy to just fill the cells on occasion and call it an inspection. Of course... after a long boondock sesh, I'll probably still want to dip the hydrometer.

I have but 240W of portable solar panels, but the rig does have a killer generator and a 100A, 3-stage charger plus equalizing mode. Would be nice to sleep soundly with the heater running... knowing I have 230 Ah to play with before the bank hits 50%.
.
KendallP
Explorer
Feb 25, 2022
time2roll wrote:
My 4x GC2 were sandwiched for a decade with no issue. I had space to water but found it way better, easier, safer to get a watering system. If you were in SoCal I would give you the set up as I have converted to LFP.

Very kind of you to offer. And thanks for the idea.
KendallP
Explorer
Feb 25, 2022
valhalla360 wrote:
If you are worried about topping up the water, you can add a battery watering system to make it easier.

Thanks!

Yeah, watering is a concern. But I also like to inspect.

That said... you guys have me thinking I can get by just adding water with a watering system when I would normally just inspect. If they're full, I'll know it because they won't take any water.
wa8yxm
Explorer III
Feb 25, 2022
4 GC-2 = 440 amp hours half usable
3 Group 27's 300 and only about 1/4 usable
no contest.
StirCrazy
Moderator
Feb 25, 2022
KendallP wrote:
.
EDIT: Regarding Question 2 below, the guys in the first few replies got me thinking I can suppress my OCD and get by adding water with a watering system when I would normally just inspect. If they're full, I'll know it because they won't take any water.

The slide-out battery tray in this motorhome is designed for 3 group 27s. It currently has 2 new ones and a slightly older one that tests almost as new via they hydrometer. The tray can also probably fit 3 29s and maybe 3 31s. All with about 3/4" between them horizontally like so...

______
I_____I
______
I_____I
______
I_____I

The tray will also just fit 4 Deka GC2s in 2 vertical pairs thusly...

___ ___
I....I I....I
I....I I....I
I__I I__I
___ ___
I....I I....I
I....I I....I
I__I I__I

Each pair might have 1/8" of gap between them, left to right. And maybe 1/2" between the top pair and the bottom pair.

Also... the back vent caps are going to be very hard to check and fill without removing the front pair of 64 lb batteries... at chest level. There was a time when I could load an awkward, 120lb 4D in and out of a tight battery compartment solo, no problem, but... I guess I'm gettin' old.

The benefit of the GC2s would be...

1. 460 Ah vs roughly 300

2. Greater deep cycling durability / longevity

3. And easier to recover from progressive sulfation incurred by successive 50-90% charges.

That's if the tray can stomach an extra hundred pounds or so.

Questions:

1. How bad would it be if the 4 Dekas were sandwiched together with no gap between them?

2. How big of a boondocker does one have to be to remove a pair of GC2s every time one needs to check the electrolyte of the other pair? Let alone top them off...
.

I have 4 GC batteries in my fith wheel for a total of 470Ah, they are sanwiched togeather in two trays and I have a auto watering system on them I found on amazon. works perfect as I used to have to unload the front storage every time I wanted to check them. now I just hook up the pump and top them off about 4 days before I go camping and done. takes 3 min start to finish to top up the batteries.

Steve
BFL13
Explorer II
Feb 25, 2022
As you know, all the load/charging should be across the whole bank and not split among battery sets ("tapping") If some of the wires now are too short to do that, you can add more wire lug to lug or however. Buss can help there.

With the GC15s you do need to check SG after even one 50-90 since the SG does not get right up to baseline SG next time you go for a full recharge. Have to do an overcharge. Usually checking one battery up front you can get at will do though.

For the platform mentioned, one way is to use a garage style tool box carrier dolly on four caster/wheels built up to the correct height to be even with the battery tray.

With 6s you can arrange them so the series wire end posts are at the back, making the parallel link and load/charging posts all at the front for easier wiring. On a tray that can also make the posts that would take a portable charger up front where you can get at them.

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