12v vs 6v House Bank

[sailor0516]

I am replacing batteries on a 44' Morgan. The house bank is 4 6v.
Would it be better to replace with 4 12v batteries?? Starting group is two 12v.
Thanks for any comments
sailor0516

[skipmac]

It might depend on which 6V battery vs which 12V battery.

I would start with the space I have and the sizes of batteries that will fit.

In general you will get more bang for the buck buying 6V golf cart type batteries, at least in FLA type. Also, 2 X 6V deep cycle batteries are a whole lot easier to haul around than 1 X 12V battery of the same total capacity.

[SailPenelope]

I have 6, 6V in the house bank, and one 12V for engine starting. Fit well in the space available, easy to replace.

[skipmac]

Originally Posted by SailPenelope

I have 6, 6V in the house bank, and one 12V for engine starting. Fit well in the space available, easy to replace.

Exactly my setup. I guess I must be doing something right.

[btrayfors]

Originally Posted by sailor0516

I am replacing batteries on a 44' Morgan. The house bank is 4 6v.
Would it be better to replace with 4 12v batteries?? Starting group is two 12v.
Thanks for any comments
sailor0516

As a general rule, 6-volt golf-cart batteries in series/parallel are a better choice for house batteries than are 12-volt batteries. This is because they have thicker plates and will withstand more charge/discharge cycles.

Twelve-volt batteries in group 27, 31, etc. have thinner plates and are not as robust as the golf-cart batteries. Larger sizes of 12-volt batteries, e.g., 4-D and 8-D, are very heavy and it's not worth risking a back injury to fit them, IMHO.

Not sure why you have two starting batteries on a 44' Morgan. One Group 31 would seem to be more than enough.

Bill

[sailor0516]

Thanks everyone, will set up 6v for the house bank as that is what is already in place.
sailor0516

[bmm32005]

Originally Posted by SailPenelope

I have 6, 6V in the house bank, and one 12V for engine starting. Fit well in the space available, easy to replace.

How many amp hours with 6 6 volts?

[sailor0516]

Have not been able to determine battery amps yet, boat is new to me so do not know from original purchase, will pull batteries soon. Thanks.
sailor0516

[Maine Sail]

Originally Posted by bmm32005

How many amp hours with 6 6 volts?

Most 6V batteries in the GC2 / T105 size case are between 215Ah & 240Ah for a pair, with 225Ah being the most common 20 hour rating.

2 would be 225Ah's
4 would be 450Ah's
6 would be 675Ah's

[MarkJ]

I can't see how double the number of 6 volt batteries is a useful thing on a boat. All the extra connections in a race to see who can corrode fastest.

If your boat is 12v why have 6 v and then make it 12v? Just plum crazy, Aunt Alfafa.
Then the inverter: 6v to 12 v to 110 or 220v. Like hows that a good idea?

[Maine Sail]

Originally Posted by MarkJ

I can't see how double the number of 6 volt batteries is a useful thing on a boat. All the extra connections in a race to see who can corrode fastest.

If your boat is 12v why have 6 v and then make it 12v? Just plum crazy, Aunt Alfafa.
Then the inverter: 6v to 12 v to 110 or 220v. Like hows that a good idea?

Because 6V batteries are a better deep cycle design lending to longer life and more cycles. They also usually cost a lot less..

For example Trojan rates their 6V T105's at double the cycles as their 12V marine SCS series...

Corrosion should not happen on any battery. If it is happening you are simply not taking care of them regularly and not using a good terminal grease.

Also in most installations when compared Ah to Ah, and foot print to foot print, a series / parallel bank will very often have less connections than a parallel wired 12V bank..

Take a 450Ah bank of 6V GC2 batteries there are only 10 connections.

Like this 450Ah bank of 6V GC2's:


To get to 450Ah in 12V group 31's this would require at least four 12V batteries and would result in at least 14 connections.

Like this 400Ah AGM bank.:


To get to 450Ah in 12V group 24's would require at least six batteries and result in 22 connections..

Here is a 6V series bank of 390Ah and just 4 connections...


And here is 210 Ah's of 12V batteries with 6 connections. That 390Ah 4 connection bank takes up the same foot print as this 210Ah bank only it is taller..


Course this is how many 12V banks look before I get to working on them...


And this is one reason the battery connections don't worry me..

[Capt RonB]

Originally Posted by MarkJ

I can't see how double the number of 6 volt batteries is a useful thing on a boat. All the extra connections in a race to see who can corrode fastest.

If your boat is 12v why have 6 v and then make it 12v? Just plum crazy, Aunt Alfafa.
Then the inverter: 6v to 12 v to 110 or 220v. Like hows that a good idea?

It all depends on the space vs capacity vs maintenance ... one 12v 8D size battery provides about 225 amp hours of capacity in a single battery that weighs about 175lbs ... two T105 6v batteries provide about the same capacity when wired in series and weigh 65lbs each. Much easier to wrestle in and out of the usual battery space.

On some boats access for maintenance is a real problem. In those cases you should consider Gel Cells or AGMs. These batteries are sensitive to charging voltages but they do not outgas (normally) and therefore terminals corrode less and you don't need access to add water. But pay close attention to manufacturer's charging specs. I had Gels in our last boat that lasted over 10 years and were still going strong when I sold the boat.

6V Golf Cart batteries at Sam's Club here in Florida were running under $100 each last time I checked. Hard to beat that

[Maine Sail]

Originally Posted by Capt RonB

It all depends on the space vs capacity vs maintenance ... one 12v 8D size battery provides about 225 amp hours of capacity in a single battery that weighs about 175lbs ... two T105 6v batteries provide about the same capacity when wired in series and weigh 65lbs each. Much easier to wrestle in and out of the usual battery space.

The real difference is that most 8D and 4D batteries are NOT true deep cycle batteries despite the misleading marking they are often sold under. They are "dual purpose" truck batteries not a true deep cycling battery. I only know of hand full of 4D or 8D true deep cycle batteries and I rarely if ever see them in actual use on boats..

[ranger58sb]

Originally Posted by Maine Sail

Take a 450Ah bank of 6V GC2 batteries there are only 10 connections.

Like this 450Ah bank of 6V GC2's:

Nice looking battery boxes, Maine. Who makes those? I take it they have lids, too, not pictured?

-Chris

[Sailmonkey]

Originally Posted by ranger42c

Nice looking battery boxes, Maine. Who makes those? I take it they have lids, too, not pictured?

-Chris

Used to be blue seas......I believe the original supplier is still making them though under for a different label.

Box Battery GolfCart - Blue Sea Systems