Batteries - 12v or 6v.

[Privilege]

I'm in need of a new battery bank to replace my four 300ah Lifeline 6v (12v system) batteries. I'm going to stick with AGM's between 500-600ah. My searching reveals that for similar price, you can get four 6v batteries or two 8D 12v batteries that cost around the same and provide around the same Ah's. Is there any advantage to choosing one over the other?

[ranger58sb]

Lots of threads suggesting 6V golf cart batteries would be better for house functions.

8Ds weigh a boatload... each... so shifting the weight of individual 6V batts would probably be easier.

Curious which Lifeline 6V batts you have, and whether that 300 Ah is total for 4 in the bank, or individual capacities? Have yours lasted from 2009 (year of boat in your avatar) 'til now? I've been gravitating toward replacing our aging 3x Odyssey PC-2150 (G31) AGMs with 4X Lifeline 6V AGM GPL-4CTs (220Ah each, 440Ah total in series/parallel to 12V).

-Chris

[ontherocks83]

8D's are not true deep cycle batteries. Due to the previous mentioned weight reasons and for being a true deep cycle, I vote 6v.

[Privilege]

Curious which Lifeline 6V batts you have, and whether that 300 Ah is total for 4 in the bank, or individual capacities? Have yours lasted from 2009 (year of boat in your avatar) 'til now? I've been gravitating toward replacing our aging 3x Odyssey PC-2150 (G31) AGMs with 4X Lifeline 6V AGM GPL-4CTs (220Ah each, 440Ah total in series/parallel to 12V).

-Chris[/QUOTE]

I've got four of the 6ct's at 300ah each, so a 600ah bank. I took them from the dump when a nice yacht was replacing their 'dead bank'. They've worked perfectly for three years since.

[Privilege]

Originally Posted by ontherocks83

8D's are not true deep cycle batteries. Due to the previous mentioned weight reasons and for being a true deep cycle, I vote 6v.

Not a very scientific approach I know but there doesn't appear to be any 'true deep cycle' difference according to the Lifeline website....

The Lifeline GPL-6CT is specifically designed for deep-cycle applications.
The Lifeline GPL-8DA is specifically designed for deep-cycle applications.

[ontherocks83]

I'm not well versed in life lines. I am much more informed on FLA. Life line may be different, I'm sure there is someone much more well versed in life lines then I am. As far as FLA 8D's are not true deep cycle. Keep us informed on what you do.

[S/V Alchemy]

Originally Posted by Privilege

I'm in need of a new battery bank to replace my four 300ah Lifeline 6v (12v system) batteries. I'm going to stick with AGM's between 500-600ah. My searching reveals that for similar price, you can get four 6v batteries or two 8D 12v batteries that cost around the same and provide around the same Ah's. Is there any advantage to choosing one over the other?

In the absence of any information as to whether you are on the hook, a mooring or a dock with shore power, or whether you have multiple solar panels or wind gen with an MPPT geared to keeping AGMs fully charged, it's impossible to give an answer.

I favour AGMs for some start applications or when the boat is left "off charge" because they self-discharge less than FLA batteries or when the only practical way to install them is on their sides. But as you are likely aware, they need special handling in terms of charging regimes. There's no reasonable answer without this info.

[ranger58sb]

Originally Posted by Privilege

I've got four of the 6ct's at 300ah each, so a 600ah bank. I took them from the dump when a nice yacht was replacing their 'dead bank'. They've worked perfectly for three years since.

Got it, thanks.

-Chris

[Sarge17]

4 x 6 for all the reasons listed above. In addition, for a 12 to equal the lead in and spacing of the plates in a 2 x 6, it would have to weigh and be twice as big. My 6's weigh 66 lbs each. I would never go back to 12's.

[a64pilot]

If you want to stay AGM go Lifelines, if you want to save a whole pile of money go with golf cart batteries.
Lifelines are one of the very few that have deep cycle 12 V batteries. I don't know of another deep cycle 12V AGM. There may be others that I don't know about.

[Privilege]

Originally Posted by S/V Alchemy

In the absence of any information as to whether you are on the hook, a mooring or a dock with shore power, or whether you have multiple solar panels or wind gen with an MPPT geared to keeping AGMs fully charged, it's impossible to give an answer.

I favour AGMs for some start applications or when the boat is left "off charge" because they self-discharge less than FLA batteries or when the only practical way to install them is on their sides. But as you are likely aware, they need special handling in terms of charging regimes. There's no reasonable answer without this info.

I think you misread the question. I have already decided to go with AGM's, I've got lots of solar and MPPT's. I was trying to figure out whether there is any difference in 12v or 6v AGM, given the similar price and similar Ah. The 12v batteries weigh roughly twice as much but I need 50% less of them.

[botanybay]

In the case of lifeline to lifeline specified similarly I would go with the smaller packages (i.e. 6v) easier to move around and mount.

8D batteries are heavy enough to end someone's cruising career due to back injuries.

Now if you can safely get the bigger batteries in and out it is probably a wash.

As said previously, lifeline batteries are specified as deep cycle, definitely not the case for most others which are starting batteries.

Sent from my SM-G935V using Cruisers Sailing Forum mobile app

[roverhi]

One of the power boats on the dock just changed out his 2 8D starter batteries. Hired a couple of young guys with strong backs to pull the batteries and a very well built cart to get them ashore. The only way to deal with 8Ds.

[Steve Bedford]

I am also looking to change out the start and house battery bank on my "new to me boat" as well. Current arrangement has two Northstar 12volt AGMs arranged in parallel for the start bank and two different size (smaller) Northstar 12 volt AGMs also arranged parellel for the house. The house bank is fine but way undersized for my house needs at anchor. There are other issues with the start arrangement that I will not go into. I have a lot of experience with six 6 volt golf cart batteries (wet cell) arranged in series and parallel for the house bank on my prior boat. I always felt the 6 volt bank was the way to go.

I have looked at and talked to many companies about their AGM batteries for both my house and start banks. A few things they all agree on (much they don't):
1. The 12 volt "long, tall, skinny" AGMs (what I currently have) all have about the same Amp hour (Ah) max threshold.
2. They are heavy!

What I have found is that 6 volt AGM come in a variety of sizes and shapes and have quite a large difference in Ahs.

One very well known company who does not specialize in start batteries said their 6 volt golf carts arranged in series can be used and are being used very successfully as start batteries. Another company, making the "long, tall, skinny" 12 volt (very expensive) says their "new and unique technology" has a higher resistance to sulfation and less need of equalization than other company's AGMs. Another company disputed that and said that AGM technology is very similar and AGMs by nature do not sulfate and you do not have to ever equalize.

There is a lot of information out there. With the success I have had in the past, at least for house banks, I will probably go with AGM 6 volts in series and parallel for the house and still undecided about the AGM start bank.
Steve

[ranger58sb]

Originally Posted by Steve Bedford

I am also looking to change out the start and house battery bank on my "new to me boat" as well. Current arrangement has two Northstar 12volt AGMs arranged in parallel for the start bank and two different size (smaller) Northstar 12 volt AGMs also arranged parellel for the house. ... There are other issues with the start arrangement that I will not go into. I have a lot of experience with six 6 volt golf cart batteries (wet cell) arranged in series and parallel for the house bank on my prior boat. I always felt the 6 volt bank was the way to go.


1. The 12 volt "long, tall, skinny" AGMs (what I currently have) all have about the same Amp hour (Ah) max threshold.
2. They are heavy!

One very well known company who does not specialize in start batteries said their 6 volt golf carts arranged in series can be used and are being used very successfully as start batteries. Another company, making the "long, tall, skinny" 12 volt (very expensive) says their "new and unique technology" has a higher resistance to sulfation and less need of equalization than other company's AGMs. Another company disputed that and said that AGM technology is very similar and AGMs by nature do not sulfate and you do not have to ever equalize.

Steve, is that a powerboat with twin diesels? If yes, do you mean you have a single shared bank for started both engines? By "long, tall, skinny" and "heavy" do you mean 8Ds?

If yes, and if you haven't looked already, Odyssey's PC-2150s (BCI Group 31) offer significant cranking amps (CCA 1150, MCA 1370) with way less weight than 8Ds. A pair of those could replace 8Ds for starting easily enough.

Our engine specs say we need 1250 CCAs with RC of 640, and 1560 MCAs with RC of 480. A pair of PC-2150s could do that easily. FWIW, our oldest bank is 11 seasons old (being replaced next season), never equalized.

That bank of ours is actually 3x batts, but it also powers house functions and runs the electronics suite. Had it just been for starting, a pair would have easily been sufficient.

-Chris