Single big battery v/s 2 batteries in parallel

RoyB wrote:
The battery AH capacity is pretty much proportional to the battery weight. For a 300AH capacity battery bank it is much easier for me to man-handle two 62lb batteries than one 128LB battery.

I sometimes don't have the room to setup a block and tackle winch to pull one of those heavy guys...

Roy Ken

The Interstate GC2's I bought are 77lb each. I'm still hurting 2 weeks later. Too old for this crap.

Having spent my Naval career (small part of my misspent youth) on a WWII fleet boat, all I can say is "huh".

Doug

I used to joke as follows.
Why two six volt in series instead of one big 12 volt? (Size 8-d)

the joke is this: You put two six volt in series you get 12 volts at 230 amp hours

You try to pick up a 12 volt 230 amp hour battery you get... A hernia.

NOT that a pair of Group 31's would put you in the same (260 AH) Ball park.

So this argues for multiple batteries in series.

As for GC-2/G-31.. GC-2 generally cost less and are TRUE DEEP CYCLE
G-31, generally cost more and though you can get 'em in Deep cycle, most you find are not.

Oh, and yes, I can pick up an 8-D safely and carry it without injury, or two G-31's at the same time.. However I know many that can not.

RoyB wrote:
The battery AH capacity is pretty much proportional to the battery weight. For a 300AH capacity battery bank it is much easier for me to man-handle two 62lb batteries than one 128LB battery.

I sometimes don't have the room to setup a block and tackle winch to pull one of those heavy guys...

Roy Ken

62 must be a typo for 82 at 300AH. :) T-1275 at 150AH. Yes they are heavy. Eat your Wheaties.

The battery AH capacity is pretty much proportional to the battery weight. For a 300AH capacity battery bank it is much easier for me to man-handle two 62lb batteries than one 128LB battery.

I sometimes don't have the room to setup a block and tackle winch to pull one of those heavy guys...

Roy Ken

I ran 2 12's for 15 yrs and was satisfied.Converter failed a while back so I bit the bullet and installed 2 GC2 6v golf cart batt's (232ah each). As well as a new Powermax 4 stage conv. Just thought I would try this setup and see if it would lessen the run time on the gen. I dry camp about 99% of the time. Haven't had it out yet so I shall see how it goes this spring & summer. With me being alone (in my trailer) almost all the time camping. I would think it could save me some fuel and hrs on the gen.

Before I would get all crazy about using a flooded 4D, 4DLT, or (8-D battery) I would check for example on the 8-D to make sure it weighed at least 150 lbs and did NOT have more than 900 CCA. A 29-plate 8-D is an engine starting battery not a cyclable battery. Keep in mind I said flooded here not AGM.

All good advice above but keep in mind the most common setup seen on travel trailers is 2 24's or 2 27's. It's a decent setup and good bang for the buck. The batteries are relatively cheap and can be had for $80 to $100 each anywhere. Not ideal, but it works fine for 90% of the folks out there.

Once you've had the above, and especially if you dry camp a lot, you start to crave more amp hours. That's where all the excellent advice posted above comes in.

On the other side of the coin are folks that only camp with full hookups and would not consider dry camping. For them, a single 24 or 27 is fine.

My new trailer came with a single 24 with a tray that will accommodate 2, so I added a second battery as we dry camp about 50% of the time. I don't have huge capacity like others but my Honda EU2000 genny is standing by if the batteries get low.

SKSCCI wrote:
people have spoken about getting 2 6 volt batteries and using them in series for a 12 volt system.

It's a toss up.

SKSCCI wrote:
Good Evening Matt!

Thanks for the details.
Here's what I got from your discussion:
1. Buy a single 200AH battery and it will be good until it dies.
2. Buy two 100AH batteries and you will get about 150AH and they will be good until ONE of them dies. When the one dies, depending on how it dies, there is a chance that it has damaged its brother in parallel. So, instead of being able to depend on a backup battery, you may be in just as much trouble if not more so with 2 in parallel.

Some people have spoken about getting 2 6 volt batteries and using them in series for a 12 volt system. Is this situation pretty much the same as far as potential problems as 2 12v in parallel?

Thanks.
Steve.

I would say you have a good interpretation there.

A good principle is to minimize the number of cells(and the number of wire connections).

Cells are the basic building unit and are nominally 2V. Battery is a plural noun, or an assembly of cells. A 6V battery has 3 cells and in series/pairs you have a 12V battery with 6 cells. A 12V battery will also have 6 cells. Two parallel 12V batteries will have 12 cells. Extra cells/connections is where you get less mean time before failure. However, it does not mean there will be a failure.

A more exact match for 2 x 6V would be an equivalent AH 12V battery in size 4D or 8D.

IMHO would rank them best to worst:

1. 4D or 8D 12V,
2. series 6V,
3. parallel 12V.

HTH;
John