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Old 05-01-2019, 17:24   #31
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Re: 4 six volts better than 2 twelve volts

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I need to speak up here.

I am replacing my three 8D AGM batteries with eight 6 volt in series parallel. I used 6 volt before and they did well for 10 years.
I replaced with the 3 expensive AGMs (About $2,000, if I remember right.) and they gave me a smaller battery bank and nothing but problems. They did not seem to actually give the amp hours they were rated at. I have a 150 amp Ample Power alternator and an advanced Balmar regulator. The AGMs never seemed to have the storage they were rated at. (West Marine batteries.)
After a dismal season last year, I bought 8 new 6-volts to replace the AGMs. When I pulled them out, I found the sealed AGMs that "never leak and never boil over" had leaked and crumbled the floor beneath them. I cut out the acid-crumbled area yesterday and am replacing it.
I always used (home-made) battery boxes with the 6 volts. But since the AGMs are "sealed and never leak or give any problems", I strapped them directly to the floor. Big mistake; they do leak. I saw leakage down the sides of two of the three AGMs.
So I will be back up to about a 900 amp hour bank for half the cost of the undependable AGMs.
Just thought I need to share this.
It is a brilliant marketing myth that AGM's don't leak. This one too had leaked itself dry.
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Old 05-01-2019, 17:32   #32
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Re: 4 six volts better than 2 twelve volts

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... which is an exide brand.
kewl, learn something new
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Old 05-01-2019, 17:34   #33
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Re: 4 six volts better than 2 twelve volts

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Something about "quality". If I were buying AGMs I would limit the search to Lifeline, who have a sterling reputation.
Odyssey and Northstar are the other two in NA market
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Old 05-01-2019, 17:37   #34
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Re: 4 six volts better than 2 twelve volts

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Was talking to a chap and told him of my possible battery acquisitions. He recommended I get 4 six volts, two wired in parallel, rather than 2 twelve volts. He said the 6 volt jobbies were better as part of battery function was dependent on size and the two 6 volts would offer more usage than an equivalent one 12 volt. Checking to see if this is true.

The actual question is, are 4 six-volt batteries better than 4 twelve-volt batteries.
The 12v deep cycle probably have 90 to 110 amp hour rating at 12v.
The 6v is rated at 225 or more but it takes 2 of them to make 12v.
So four 12v batteries give you about 400 amp hours of storage and four 6v batteries give you about 450 amp hours.
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Old 05-01-2019, 17:39   #35
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Re: 4 six volts better than 2 twelve volts

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Odyssey and Northstar are the other two in NA market
I think you mean to say the other two quality AGMs, which I have also read, so add them. Full River make a lot of AGMs, but I haven't read that they are in the top level. They are more common in RVs I think.


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Old 05-01-2019, 17:40   #36
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Re: 4 six volts better than 2 twelve volts

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It is a brilliant marketing myth that AGM's don't leak. This one too had leaked itself dry.
My battery cases were intact. The AGMs leaked from the caps and I could see where it ran across the top and down the sides. At least 2 of the 3 leaked.
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Old 05-01-2019, 17:41   #37
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Re: 4 six volts better than 2 twelve volts

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Originally Posted by rsn48 View Post
Was talking to a chap and told him of my possible battery acquisitions. He recommended I get 4 six volts, two wired in parallel, rather than 2 twelve volts. He said the 6 volt jobbies were better as part of battery function was dependent on size and the two 6 volts would offer more usage than an equivalent one 12 volt. Checking to see if this is true.
28' boat you may want to consider the weight issue. Lowest cost 6v x 2 setup may do the trick as long as you keep them watered properly. 4 of them would be heavy.

I would have you consider Firefly Oasis. Best of the Lead Acid technology IMO. They sell them in 12v G31 size. Two might be perfect for you.

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I have tried 6 volt gold cart batteries and I didn't like them.

Problems I had:
1. They were taller and didn't fit well into the battery compartment. Got them in but had only a half inch to spare. This is unlikely to be a problem for others but it is something to consider.
2. The complicated wiring with multiple connections. I have no problem with this but there are a lot of connection points to corrode.
3. I didn't get very long life out of my setup either. I got my batteries at Costco here in the USA. Nothing special, but certainly not real cheap ones either. Two years later they had to be replaced. This was my fault because they were in such a tight space that all cabling had to be removed to get the batteries out to check the water. This took about a half hour so I didn't do it often. Bad dog.
This brings up an important point. AGM's require less service. Seem to take abuse better. Can be mounted anywhere even of their side. Don't boil over. Don't loose water (they are a mat internally). Will continue to work if the case is damaged. Don't seem to have corrosion at the terminals. They DO COST more but I have gotten much longer service life.
My current setup is a single 8D Trojan AGM with a forklift quick disconnect and a separate AGM start battery. For those not familiar with a forklift disconnect they are used to charge forklifts overnight and both cables are lead to a heavy duty shielded plug that is rated in amps. Typically plug ratings are 250 to 500 amps. Just grease the internal part of the plug and it snaps together (with some force) making a tight connection. The terminal connections on the battery are never disturbed. Very simple and fool proof. To disconnect the battery just pull apart. Because the plug is fully insulated you don't have to worry about shorting the battery when unplugged. Just don't stick a screw driver into the plug!
Now, not everyone wants an 8D because it weighs about 130lbs or 50k aprox. I've had mine for 5 years now with no problems. My point here isn't about the 8D but about simple battery wiring. Whether you are talking about a couple of 12v deep cycles, 4D's or larger, I believe simple is better. Hope this helps. Thought I'd give a different perspective.
CaptainJohn49
This clearly seems like you shouldn't have installed FLA.

What brand 8D weigh 130 lbs? I got rid of 3 Lifeline 4D's and they were 124 lbs each. Their 8D's are 154 lbs.

Typical AGM's are sensitive to partial state of charge. This is a huge weakness for a sailboat, especially at a premium price.
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Old 05-01-2019, 17:47   #38
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Re: 4 six volts better than 2 twelve volts

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I would have you consider Firefly Oasis. Best of the Lead Acid technology IMO. They sell them in 12v G31 size. Two might be perfect for you.
I was looking at them. Then I was looking for them. Fat chance. They are having mega delivery problems. Fisheries Supply (one of the largest U.S. marine distributors) took them on last year. Now they can't say when they will receive any, and gave up on accepting backorders. (Recent experience) Until they get their manufacturing/delivery act together this isn't an option for most of us.

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Old 05-01-2019, 17:57   #39
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Re: 4 six volts better than 2 twelve volts

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I think you mean to say the other two quality AGMs, which I have also read, so add them.
Yes, also Firefly, but $pecialist for resisting PSOC abuse.

Full River is OK, but not as good as the above 4.
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Old 05-01-2019, 17:59   #40
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Re: 4 six volts better than 2 twelve volts

Firefly
> having mega delivery problems

Yes I had to wait four months for my last batch.

Bruce @ OceanPlanet is best point of contact.
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Old 05-01-2019, 18:04   #41
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Re: 4 six volts better than 2 twelve volts

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I was looking at them. Then I was looking for them. Fat chance. They are having mega delivery problems. Fisheries Supply (one of the largest U.S. marine distributors) took them on last year. Now they can't say when they will receive any, and gave up on accepting backorders. (Recent experience) Until they get their manufacturing/delivery act together this isn't an option for most of us.

Greg
That only applies to the G31 12v batteries. I was able to purchase three 4v L15+ with no waiting last autumn. 450 ah @ 12v. Approximately 35-40% greater cycle life per their published specs as compared to the G31 units. I have no idea why more aren't using the 4v models. The 94 pounds was refreshingly light compared to the 4d 125# pieces I replaced.
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Old 05-01-2019, 18:10   #42
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Re: 4 six volts better than 2 twelve volts

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No, the inherent design and build quality is what's being discussed, for deep cycling use.
I have no idea what you are discussing, but the OP has clearly asked whether two 6V batteries are better than one equivalent 12V.
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Old 05-01-2019, 20:39   #43
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Re: 4 six volts better than 2 twelve volts

Two 6 volts are fine until one cell goes bad and then you no longer have 12 volts.
if you have 2- 12 volts and one cell goes bad you still have 12 volts. You can't start an engine on 6 volts
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Old 05-01-2019, 21:59   #44
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Re: 4 six volts better than 2 twelve volts

So I have also being looking at lithium, and I'm in a refit stage where adding them now might be the time to do it as I am redoing much of the electrical, charging system, adding Efoy 210 and increasing alternator to 140 AMP. I'll link a video made by "Gone with the Wynns" who did switch over to lithiums. This video isn't their best, they should have redone it, but it gets the points across. Skip to the 4 minute mark to save some time. I'll also link their web page about lithuims which is better than the video.

[Just a quick comment from another poster here on my boat being 28 feet and battery weight may be a problem. My boat is more tug like than express cruiser. Since it is a 1969 build - 50 years old now - the hull is original build fiberglass on plywood, resulting in a hull that is an 1 1/2" thick. The weight of the boat is roughly 13,000 pounds which is more like a 33 footer today. This boat is a bruiser, heavily built, not delicate of touch and feel, and can easily handle extra weight]

This is the Wynn's first year on their cat boat but they did live off the grid in a large expensive motorhome for 7 years. So they know battery demands etc. They also use their air conditioner with their electrical set up, but they spent major bucks on their system, which you will see more on the web site than their video:

Their web page on lithiums and why they chose them:

https://www.gonewiththewynns.com/sai...hium-batteries

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Old 06-01-2019, 04:41   #45
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Re: 4 six volts better than 2 twelve volts

Well then price is obviously not a concern, and that changes everything.

I would advise starting a new thread titled appropriately for the specific topic, question you want answered, to attract more and better responses.

Would replacement fuel for your Efoy be readily available in your cruising grounds?
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