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Old 04-01-2019, 17:30   #1
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4 six volts better than 2 twelve volts

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.
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Old 04-01-2019, 17:39   #2
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4 six volts better than 2 twelve volts

Most likely true.
Reason is there aren’t many actual true deep cycle batteries, and they few there are, like Rolls and Lifeline are not inexpensive at all.
However there are millions of 6V traction batteries, AKA golf cart batteries, and they are truly deep cycle batteries, and from a cost Vs value perspective, they are a very good buy.

So what is a deep cycle battery?
https://marinehowto.com/what-is-a-deep-cycle-battery/
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Old 04-01-2019, 17:50   #3
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Re: 4 six volts better than 2 twelve volts

tough to beat 6v. trojans wired for 12 volts. they are bigger than the regular 12v. batteries though. then again you are getting around 450 ah. for the 4 batteries.
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Old 04-01-2019, 18:22   #4
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Re: 4 six volts better than 2 twelve volts

Plus the six volt batteries are easier to move on and off the boat.

How many boaties does it take to get an 8D battery into place?
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Old 04-01-2019, 18:23   #5
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Re: 4 six volts better than 2 twelve volts

Not theoretically avoiding value for money

but definitely from a practical, cheap and easy POV.

The best battery value by far in the US market, is Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, 2x6V, around $200 per 200+AH @12V pair from BatteriesPlus or Sam's Club. Deka labeled same batts also sold at Lowes.
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Old 04-01-2019, 20:57   #6
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Re: 4 six volts better than 2 twelve volts

Of course 4 is better then 2...

It's ~450ah. Vrs say 200ah for a pair of group 31's
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Old 04-01-2019, 21:51   #7
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Re: 4 six volts better than 2 twelve volts

OP did say "equivalent", so that has to mean AH, if nothing else.

6x 2V cells would be even better, likes of Rolls / Surrette, but don't ask how much 8-)
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Old 04-01-2019, 22:50   #8
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Re: 4 six volts better than 2 twelve volts

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Originally Posted by john61ct View Post
OP did say "equivalent", so that has to mean AH, if nothing else.

6x 2V cells would be even better, likes of Rolls / Surrette, but don't ask how much 8-)
Concur!
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Old 05-01-2019, 07:58   #9
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Re: 4 six volts better than 2 twelve volts

The 48v propulsion bank on Mr Wiggles is made up of GC-2 size golf cart batteries from Sams Club, $85/ea and at 4 years old, are still perking along nicely. Went in and had a look recently and they are still $84.99 or something like that. 220ah for mine. That's a lot of battery for the buck. NO WAY could I make up a comparable bank of 4D or 8D batteries less than twice that cost. Golf cart batteries ROCK. Handy size/weight, too. Be sure and get a couple of lifting straps cause GC batteries don't usually have handles. The rubber strap type with the double hooks on each end is cheap. Only down side is twice as many connections, so do them up right.



Longest lived FLA batteries, highest quality, definitely the Rolls single cells, and I am thinking about getting 6 1000ah Rolls cells for my house battery in Brute Force. Maybe an 8D for reserve house power, but a separate start battery for the Westerbeast. Still, my wallet feels the call of the GC-2...



Have I ever mentioned that I don't care for parallel batteries? LOL. But two separate series banks isolated/paralleled by a two bank battery switch is not a bad option. Assuming smallish DC loads of course, where Mr Peukert doesn't complicate things.
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Old 05-01-2019, 10:03   #10
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Re: 4 six volts better than 2 twelve volts

You tell me. As long as you can manage the correct wiring and be sensitive to load balancing and keeping the interconnections the same length, you can have a huge, reliable bank at little cost. This is 1185 Ah at 12VDC nominal. This is on the centerline, under the mast and under the saloon stairs, about as good a hidey hole as is possible on a 40 footer:
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Old 05-01-2019, 10:07   #11
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Re: 4 six volts better than 2 twelve volts

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.



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Old 05-01-2019, 10:11   #12
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Re: 4 six volts better than 2 twelve volts

As pointed out many of the big 6volt are real deep cycle batteries made for golf carts......it's the form factor, what fits under a golf cart seat so 2 or 4, 6 volt are a better fit than lighter 12 volt batteries, also pointed out above there are great deep cycle 12 volt batteries but they cost much more.....
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Old 05-01-2019, 10:15   #13
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Re: 4 six volts better than 2 twelve volts

Quote:
Originally Posted by rsn48 View Post
two 6 volts would offer more usage than an equivalent one 12 volt
The statement above is false.

The only difference is that each 6V battery will be lighter and easier to handle than the 12V unit. If that is desirable, 6 2V cells would be even better. Also, will eliminate a parallel connection (of 2 12V units), which will potentially extend battery life and increasy effective capacity.
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Old 05-01-2019, 10:26   #14
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Re: 4 six volts better than 2 twelve volts

Quote:
Originally Posted by S/V Alchemy View Post
You tell me. As long as you can manage the correct wiring and be sensitive to load balancing and keeping the interconnections the same length, you can have a huge, reliable bank at little cost. This is 1185 Ah at 12VDC nominal. This is on the centerline, under the mast and under the saloon stairs, about as good a hidey hole as is possible on a 40 footer:
Six golf cart batteries is more like 600 amp hours at 12 volts. Sorry to burst your bubble but when there are two batteries in series the amp hours are not added together. Unless there are another six batteries not shown in your photograph you have half the AH you think you have,
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Old 05-01-2019, 10:43   #15
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Re: 4 six volts better than 2 twelve volts

Yes, the 4 6v will provide better service as a house bank however, on your boat you should be able to get the job done with 2 6v deep cycle.
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