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Old 12-18-2017, 05:44 AM   #1
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4x6v VS 2x12v

Hi,

could anyone figure out exactly what the difference between 4 x 6v vs 2 x 12v house battery bank?

My boat 4 x 6v apparently comes with the 110ah first installing batteries in my NT37 and they will start to turn on condition. Here in Finland 6v batteries are very rare, but it is possible to order. 12V batteries are easy to find anywhere.

Therefore I ask for a difference if each bank 4x6v 110Ah or 2 x 12v 220 ah, what is the difference between these two?

Electricity is a bit mystic to me

NBS

P.S Sorry for all, this has certainly been discussed earlier, such as anchors, so I hope the simplest answer to my question
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Old 12-18-2017, 06:06 AM   #2
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The energy is stored by LEAD , which is heavy .

Simply find out the weight of the batt sets , heavy has the best capacity.

"12V batteries are easy to find anywhere."

Its not a just a 6v or 12v question, House Batteries MUST be "Deep Cycle" to survive .

IF you can locate real deep cycle batts sometimes sold as" golf cart" batts ,

which ever you choose will make little difference , if the combined set weight is similar.
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Old 12-18-2017, 06:49 AM   #3
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Things to consider:

Can you substitute two 12 volt for four 6 volt. Tricky, a popular brand here in the United States is Trojan. Their 6 volt Trojan 105 provides 225 amp hours (6 volt) and weights 28 kilos. Two of these would produce 225 amp hours at 12 volts. Trojan's largest 12 volt deep cycle is the T 1275. It weights 39 kilos but produces only 150 amp hours at 12 volts. Thus you would need more than two of the 12 volt batteries to equal your current bank size of 450 amp hours at 12 volts (4 six volt batteries provide 900 amp hours at 6 volts or 450 amp hours at 12 volts). You would need three of these batteries.

A major reason that the six volt deep cycle batteries are popular in the United States is that they are cheap. They are used in golf carts by the hundreds of thousands. A six volt battery is also easier to carry (28kg) then the equivalent 12 volt battery.
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Old 12-18-2017, 07:07 AM   #4
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Here is a little physics/math to answer your question:

You need 12 volts to power your boat's electrical systems. If you do that with 12V batteries, the biggest you can find and easily install are Group 31 and they typically have about 100 amp hours each. So just multiply the number of 12V batteries by 100 amp hours and that is the total capacity you have.

Golf cart batteries are about 220 amp hours but are 6V. So you need to hook them up in pairs in series to make the 12V you need. When you hook two 6V batteries in series to make 12V you then get 220 amp hours for the pair which is about the same as a pair of 12V Group 31 batteries hooked up in parallel.

So the amp hours are the same between the two types of batteries, you just have to use GC batteries in pairs, ie 2, 4, 6, etc.

The real advantage of GC batteries is that they are made specifically for deep cycle use unlike most 12V batteries which are made for starting engines and won't last as long.

So you asked about 4x6V vs 2X12V batteries. The former have 440 amp hours and the latter about 200 amp hours of capacity assuming that the 12V ones are Group 31s.

David
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Old 12-18-2017, 07:27 AM   #5
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Quote:
Originally Posted by North Baltic sea View Post

Therefore I ask for a difference if each bank 4x6v 110Ah or 2 x 12v 220 ah, what is the difference between these two?
I think the short answer, if the amp hours you cite are the ratings for each battery, is that the 6-volt bank will have half the amp hours of the 12-volt.

The six-volt battery ah rating is based on two batteries wired in series to reach 12 volts. It takes two 110 ah 6-volt batteries, wired as a 12-volt pair, to equal a single 110 ah 12-volt.

Four 6-volt batteries at 110ah per battery = 220 ah for the bank
Two 12-volt batteries at 220 ah per battery = 440 ah for the bank
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Old 12-18-2017, 07:39 AM   #6
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Quote:
Originally Posted by FF View Post
The energy is stored by LEAD , which is heavy .

Simply find out the weight of the batt sets , heavy has the best capacity
Just to pick nits....

The energy is actually stored on the SURFACE of the lead. More surface area = more energy stored. You can have a single block of lead, which is heavy, but not much surface area. In this extreme case just the weight would not be (technically) correct. This is why the spiral-wound batteries have so much capacity - HUGE amount of surface area (thin lead sheets separated by a dielectric separator).

After that, the longevity of the battery, in terms of charge cycles, is due to the thickness of the lead (plates) which are providing this surface area. They can erode over a number of cycles and can also become (electrically) contaminated, reducing the capacity to accept/hold a charge. In this case, for a given surface area, weight *is* a big factor (thicker plates) and is a good measure of longevity.

Just clarifying.....
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Old 12-18-2017, 07:47 AM   #7
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Quote:
Originally Posted by North Baltic sea View Post
My boat 4 x 6v apparently comes with the 110ah first installing batteries in my NT37 and they will start to turn on condition. Here in Finland 6v batteries are very rare, but it is possible to order. 12V batteries are easy to find anywhere.

Therefore I ask for a difference if each bank 4x6v 110Ah or 2 x 12v 220 ah, what is the difference between these two?

Your installation sounds odd, to me.

I'd have thought your 4x6V arrangment would give you 220-Ah per 6V pair or 440-Ah total.

A typical 2x12V set-up using Group 31 batteries might be 110-Ah per battery or 220-Ah total, and 2x12V using 8Ds might be 245-Ah per battery, or 490-Ah total.

So may be useful to mention exactly what 6V batteries you have (brand/model/etc.), and exactly which 12V batteries you're considering as potential replacement?

In many cases, the decision is driven by a) purpose (house or start or both), b) total capacity (Ah), c) physical size of bank relative to size of available space, and d) weight of individual batteries. The first is generally about whether you need deep cycling or not, and it sounds like this is your house bank that you're talking about (deep cycling is good for that). The last, weight of individual batteries, can be about how much pain your back can stand.

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Old 12-18-2017, 07:48 AM   #8
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Good explanation, Ranger, of Volts and the relationship to amps.

I had a righteously certain first mate (Admiral) on the Dock explain to me how powering her 110v AC Refer was so much more efficient than my 3 Engle units that pull 2.5 amps each @ 12v since hers only only used 1.75 amps, before the inverter.
Her tone dictated a smile from me, a nod and I said “Excellient”. Then moved on.

My quick cipher is to look at the amp rating of a 6v and think of x 2 batteries for my applications. I run 10 Crown 6v at 225 or 235a each..(forgot) fed by 720 watts of solar. They can be @65% and floating by 10:30 or so. Need more batteries but no room. If in clean salty water I dump excess to the water maker.
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Old 12-18-2017, 08:16 AM   #9
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Thanks for the answers I think I understand Little. I only know they are 6v and there are 4 pcs. and the system is 12v. I have read that the NT37 total capacity of 440ah AGM. Do we understand that one 6v battery is 220ah and 4 pieces total coupled to 12 volts would be 440 ah? (I've seen batteries only in the upper part because the boxes are still connected.)


The second question I have found two brands 6v Trojan and Lifeline what you find, the prices here are quite expensive, I think around one pcs. US $ 160/440 trojan is cheaper..


I would like to go easy and get the batteries to fit in the existing very nise and safety box (Bluesea)


NBs
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Old 12-18-2017, 09:02 AM   #10
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Check with a Crown Forklift dealer there in Finland and see what he can do for you. Over here they were quite a bit cheaper than Trojan with equivalent weight and rating.

Also look into solar batteries. I know a guy that took 6 huge Trojan 2volt batteries (normally home solar) to make 12 volts for a massive amp bucket. If solar is moving into Finland in a big way that might be a good option.
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Old 12-18-2017, 09:14 AM   #11
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I used to shop at a discount supermarket called Pac-n-Sav. I use this as a mnemonic to help me remember that Parallel Adds Current -n- Serial Adds Voltage.

So, two 6 volt batteries wired in serial will double the voltage to 12 volts, at the same current as each individual battery. Two 12 volt batteries wired in parallel will double the current, at the same 12 volts.

In your setup, with four 6-volt batteries at 110 ah each, you would make two pairs of batteries that are wired in series. This gives you two banks (pairs) of 110 ah at 12 volts. Then you wire those two banks together in parallel, to double the current (the ah capacity). Now you have a total bank of 220 ah at 12 volts.

If you have two 12-volt batteries at 220 ah each, and you wire them together in parallel, you end up with a 12 volt bank at 440 ah.

As mentioned, 6-volt batteries are popular in the US both because they are readily (and cheaply) available, and because each battery will weigh approximately half as much as a 12-volt battery of equal ah capacity (making them easier to handle).

Hope that helps.
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Old 12-18-2017, 10:33 AM   #12
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Has anyone got 18 8D batteries in a single boat? Seems like overkill to me.

2006 Roberts Long Range Cruiser 650 Power Boat For Sale - www.yachtworld.com

Batteries 8D, 18 each, new 2015
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Old 12-18-2017, 10:34 AM   #13
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18 x 161lbs = 2898lbs !!!!
4100+ Amp Hours!
49kWh!?!?

Yikes! Get me some refrigeration!
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Old 12-18-2017, 10:53 AM   #14
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It may be all electric LRC

the description did say heavily ballasted, I guess that means batteries?
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Old 12-18-2017, 12:07 PM   #15
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Most boats can't get access with forklifts, so splitting up the 12V strings at hundreds of kilos each into cells a human can carry makes sense.

And nearly all 2V, 4V and 6V industrial strength batteries are specifically designed for long life in heavy deep cycle applications.

There are 12V true deep cycle batteries, but they are very rare, most that claim to be may only last half as long as lower voltage ones.

And for high AH banks too many parallel connections cause imbalance problems.
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Old 12-18-2017, 12:57 PM   #16
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North Baltic, you seem pretty fluent in English. Get yourself a copy of Nigel Calder's "Boat Owners Mechanical and Electrical Manual", which will explain this and other matters electrical in simple, easy to grasp terms.
, and
You should be able to find all varieties of 2, 6 and 12 volt deep cycle batteries over there from European brands. Mastervolt and Victron come to mind as top-tier battery suppliers to name two.

https://www.mastervolt.com/products/...ies-terminals/

https://www.victronenergy.com/batteries
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Old 12-18-2017, 02:55 PM   #17
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Mastervolt Battery Bank

Here is a prime example of a older Mastervolt battery bank. I don't remember the size but think it was around 1400 amp hours at 24 vdc.

Many of their newer offerings are Lithium iron phosphate instead of gel cell batteries.
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Old 12-18-2017, 06:57 PM   #18
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http://www.dynobattery.com/products/...-cart/d125.php

DT125

Wired series/parallel = 470ah
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Old 12-18-2017, 07:35 PM   #19
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Yes if you want good deep cycle in 12V format, those are good ones.

Probably not easily found in Finland?

Rolls may well be though.
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Old 12-18-2017, 08:04 PM   #20
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Trojan lists a distributor in Finland. Master Distributors | Trojan Battery Company
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