I have the standard 6v/series system on my trailer and find that with 300w of solar and a 30a controller all is good. Reading this article posted below it states that you don't gain amp/hr with 6v series but 12v wired in parallel gives you twice the amp/hr. So why did I spend extra money for the 6v set up when it seems as though you'd get more bang for buck with a couple of 12v deep cycles in parallel? What is it that I'm missing here? There has to be some reason that golf cart manufacturers use the 6v series system.

While the article is correct about series and parallel amp-hours, the examples they used are not even close.A typical group 27 12V battery is around 100 Ah and the 6V of similar size is more than 200. So usually you gain a little going to 6V.I think the reason golf carts prefer 6V is because the same case only has 3 (2V) cells and therefore the plates are thicker and more rugged.

wnjj wrote:A typical group 27 12V battery is around 100 Ah and the 6V of similar size is more than 200. So usually you gain a little going to 6V.x2The 12v example above is true, but misleading. You are not likely to find a 12v battery (that you can lift) of much over 100ah.

Misleading to compare GC2 and 8D :R

You can get more bank for the bucks up to a point. Thanks to the golf cart world you can find 6vdc 220AH batteries fro around $70-$80 each. Of course you will need two of these 220AH batteries in series to give the 12VDC you need for the trailer. Two 6V 220AH batteries in series will give you 12VDC at 220AHs capacity for $140-$160... Try buying two 12VDC 110Ah Batteries to connect in parallel to give you the 220Ahs capacity for #140 - $160...You also will see the two 6vDC batteries will weigh more then the two 12VDC batteries which means they will have larger cores inside. This almost directly gives you more RESERVE POWER to use time wise...That was the way I justified it in my mind...Personally I would rather have 12VDC batteries in parallel just for the possible rare occasion I have a 6VDC battery failure which would put me dead in the water...Roy Ken

RoyB wrote:Personally I would rather have 12VDC batteries in parallel just for the possible rare occasion I have a 6VDC battery failure which would put me dead in the water...If you plan on running your batteries into the ground before replacement, then 12v is a better choice because one will surely fail first. Catastrophic premature battery failure is extremely unlikely.You will sacrifice AH capacity for that choice however.

6v series vs. 12v parallel | Good Sam Community

wnjj
Explorer II
May 06, 2017
While the article is correct about series and parallel amp-hours, the examples they used are not even close.

A typical group 27 12V battery is around 100 Ah and the 6V of similar size is more than 200. So usually you gain a little going to 6V.

I think the reason golf carts prefer 6V is because the same case only has 3 (2V) cells and therefore the plates are thicker and more rugged.
2oldman
Explorer II
May 06, 2017
wnjj wrote:
A typical group 27 12V battery is around 100 Ah and the 6V of similar size is more than 200. So usually you gain a little going to 6V.
x2

The 12v example above is true, but misleading. You are not likely to find a 12v battery (that you can lift) of much over 100ah.
time2roll
Nomad
May 06, 2017
Misleading to compare GC2 and 8D :R
RoyB
Explorer II
May 06, 2017
You can get more bank for the bucks up to a point. Thanks to the golf cart world you can find 6vdc 220AH batteries fro around $70-$80 each. Of course you will need two of these 220AH batteries in series to give the 12VDC you need for the trailer. Two 6V 220AH batteries in series will give you 12VDC at 220AHs capacity for $140-$160... Try buying two 12VDC 110Ah Batteries to connect in parallel to give you the 220Ahs capacity for #140 - $160...

You also will see the two 6vDC batteries will weigh more then the two 12VDC batteries which means they will have larger cores inside. This almost directly gives you more RESERVE POWER to use time wise...

That was the way I justified it in my mind...

Personally I would rather have 12VDC batteries in parallel just for the possible rare occasion I have a 6VDC battery failure which would put me dead in the water...

Roy Ken
2oldman
Explorer II
May 06, 2017
RoyB wrote:
Personally I would rather have 12VDC batteries in parallel just for the possible rare occasion I have a 6VDC battery failure which would put me dead in the water...
If you plan on running your batteries into the ground before replacement, then 12v is a better choice because one will surely fail first. Catastrophic premature battery failure is extremely unlikely.

You will sacrifice AH capacity for that choice however.
jharrell
Explorer
May 06, 2017
Lead Acid batteries have basically the same energy density regardless of voltage. A 6V and a 12V of the same size and weight will have basically the same watt-hours. So the 6V will have twice the AH of the 12V at the same size, A*V=W after all.

Not sure why we measure batteries in AH, if you look at Lithium packs for electric cars its all KWH because voltage varies and watt-hours are what matters.
time2roll
Nomad
May 06, 2017
I would guess 12v house batteries die suddenly with a shorted cell or something 10x more often than GC2.

I will take my chances on GC2 any day. Besides no one is really on a expedition. Just pick up a new battery on the road if needed.
landyacht318
Explorer
May 06, 2017

Deep cycle duty calls for deep cycle batteries, not just a sticker on a car jar size 12v battery that says deep cycle.

http://www.pbase.com/mainecruising/deep_cycle_battery&page=1
2oldman
Explorer II
May 06, 2017
We've had just a few discussions about this over the years:

12v vs 6v.. which charge faster? 2014
12v or 6 Dec 2013
2- 12v or 6v June 2013
12v vs 6v batteries 2013
12v vs 6v batteries 2006
More 12v vs 6 2006
12v vs 6v 2010
Why 2 6? 2006

Anybody had one 6v fail?2010

maybe 12v is better 2010
12v vs 6v Feb 2010
time2roll
Nomad
May 06, 2017
landyacht318 wrote:
http://www.pbase.com/mainecruising/deep_cycle_battery&page=1

Great read. For those looking for the definition of a "true deep cycle" battery I think we have found it.