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Replacing two 6 volt house batteries with one 12 volt

Monaramblee
Explorer
Explorer
08 Holiday rambler Vacationer diesel
with two 6 volt batteries for the house and two 12 volt batteries for the chassis.
I would like to replace the two 6 volt batteries with one 12 volt marine/rv battery.
We dont dry camp anymore. Any issues with this idea?
2008 Holiday rambler Vacationer XL
340 HP Cummins
31 REPLIES 31

Monaramblee
Explorer
Explorer
I got the 12 volt deep cycle battery and it was a challenge getting the cables to reach the terminals. Had to install it on an angle but it worked.
2008 Holiday rambler Vacationer XL
340 HP Cummins

Veebyes
Explorer II
Explorer II
BFL13 wrote:
Honest question--I don't know---can a single 12 house as the Aux, start the Diesel engine, which now has two 12s for it, if those two 12s are dead?


It is all in the switching. Via battery switches you can use or combine any battery bank for any purpose.

I have a boat that had 6 grp 31 gel cell batterys arranged in 3 battery banks. I could use any of those 3 banks for starting, house or all together. The drill was to put all together when running & take one bank out of line when anchored leaving the amperage of 4 grp 31s available for the house. Something like having 6 6V GC batterys.

If you like to dry camp battery power & water capacity are king.
Boat: 32' 1996 Albin 32+2, single Cummins 315hp
40+ night per year overnighter

2007 Alpenlite 34RLR
2006 Chevy 3500 LT, CC,LB 6.6L Diesel

Ham Radio: VP9KL, IRLP node 7995

Monaramblee
Explorer
Explorer
Yes this is why i feel the 12 volt battery might be a better choice for me.
Thankyou to all for the feedback.
2008 Holiday rambler Vacationer XL
340 HP Cummins

valhalla360
Nomad III
Nomad III
If you are keeping the starting battery topped up, you should never need to break out the generator but yes it will work. Note: the typical generator 12v system is only 8-10amp and it's unregulated. OK in a pinch but it will be slow.

It's not so much 6v vs 12v for CCA...it's deep cycle vs starting battery. CCA correlates closely to the surface area of the plates in the battery.
- The 6v golf cart batteries are designed for deep cycle use in golf carts. They have a smaller number of lead plates but the plates are thicker. There is no harm in using them for starting but they won't generate as many CCA.
- The 12v starting batteries are designed to put out a huge boost of power to start an engine and then the engines alternator is providing the ongoing power. They have more but thinner plates. The extra plates provide ore CCA.
Tammy & Mike
Ford F250 V10
2021 Gray Wolf
Gemini Catamaran 34'
Full Time spliting time between boat and RV

Monaramblee
Explorer
Explorer
Googled the cold cranking amps of 6 volt batteries and it seems that a 12 volt marine style battery will have double the cranking amps in the event it is needed to boost the engine. So half the working amps but double the cranking capacity. Is this correct?
2008 Holiday rambler Vacationer XL
340 HP Cummins

Monaramblee
Explorer
Explorer
Im parked seasonally currently but i was thinking that if and when the engine batteries need a boost, i would start the genny and put the external charger in to play. I do keep the engine batteries topped up with a solar panel while camping.
2008 Holiday rambler Vacationer XL
340 HP Cummins

valhalla360
Nomad III
Nomad III
Monaramblee wrote:
The 12 volt battery i have my eye on has 800 cold cranking power and 80 amp hours.
I dont know the cold cranking power of the 6 volt batteries.


Borderline for a diesel. If the main truck batteries are just down and you hook the battery up with thick jumper cables, probably will be enough.

If the truck batteries are completely dead, good chance it won't be able to do it.

The difference between gas and diesel: Diesel starters have to overcome much higher compression and they have to spin fast enough to self ignite the fuel/air mixture before the walls of the cylinder absorbs the heat generated by compression. Gas engines have lower compression to overcome and the spark is what sets off the fuel.
Tammy & Mike
Ford F250 V10
2021 Gray Wolf
Gemini Catamaran 34'
Full Time spliting time between boat and RV

Monaramblee
Explorer
Explorer
pianotuna wrote:
BFL13,

Gas maybe, diesel very iffy.


Why not diesel? Cranking power?
I was thinking that a 12 volt battery might have more cranking power then a 6 volt if needed to assist in starting the diesel engine but im not sure.
2008 Holiday rambler Vacationer XL
340 HP Cummins

pianotuna
Nomad II
Nomad II
BFL13,

Gas maybe, diesel very iffy.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

Monaramblee
Explorer
Explorer
The 12 volt battery i have my eye on has 800 cold cranking power and 80 amp hours.
I dont know the cold cranking power of the 6 volt batteries.
2008 Holiday rambler Vacationer XL
340 HP Cummins

BFL13
Explorer II
Explorer II
Honest question--I don't know---can a single 12 house as the Aux, start the Diesel engine, which now has two 12s for it, if those two 12s are dead?
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

midnightsadie
Explorer II
Explorer II
X3 can,t beat wal mart, theres one on evvery corner.

RAS43
Explorer III
Explorer III
midnightsadie wrote:
go get a wal mart deep cycle marine battery biggest that will fit. been using them for years no problem.mine are four years old last month.


X2 Mine usually last 4-5 years and are reasonably priced and easy to find.

pianotuna
Nomad II
Nomad II
Any size agm or sealed battery.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.