batteries 12V or 6V ????

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daveem

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I am running a travel trailer with all the necessities drawing power.  I had a 12V battery last year that worked great( ran for at least 2 days running lights and water pump).  This year it dosnt work at all.  I found that one cell is completely dead.  Since i have to get a new one, I figure I might as well add a second battery.  My question is with running a new one should I run 2 12V or 2 6V?  Which way gives you more time with your charge?  What are most people running today? 
Some people tell me that two 6V are the way of the past, but on the other hand ive been reading that you get roughly 20% more time from them.
Do two 6V charge the same as my 12V does right now
thanks, Dave
 

Ned

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Two 6v golf cart or other deep cycle batteries will generally give you more AH capacity than a single 12v battery.  Connect them in series and charge them as you do a 12v battery.
 

1996terry

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I've also heard that the two 6volt wired in series will discharge at a slower rate then 12 volt batteries.

Personally, on my families' Terry TT we have two 12 volt deep cycle wired in parallel and we've stayed in some secluded areas for 3-4 days with quite a bit of battery reserve left. We just ran a couple lights here and there, the water pump, furnace, and the fridge seems to use battery power to get itself going on propane. If you do alot of moving around, and stay in one place a couple nights only, if your tow vehicle (if it has the charging line) should charge up your batteries some when you are moving on to the next place down the road.
Hope this is of some use to you!

- Jeff L.
 

Ned

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I've also heard that the two 6volt wired in series will discharge at a slower rate then 12 volt batteries.

The rate of discharge of a battery is a function of the load, not if it's a 12v or 2 6v in series.
 

Gary RV_Wizard

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If you get 6V wet cell batteries, they will undoubtedly be  "Golf Cart" batteries, type GC, which provide about 220 amp-hours of 12V service when paired in series.  If you get 12V wet cell batteries, you may have any of 3 common sizes, each of which has a different amp-hour capacity. These are (typically):
Type 24 -  85 a-h each x 2 = 170 a-h
Type 27 - 105 a-h each x 2 = 220 a-h
Type 31 - 115 a-h each x 2 = 230 a-h

So, a pair of Type 27 12V's will yield about the same amount of power as a pair of 6V GC's.  However, there is a practical advantage to the Type GC batteries:  they are designed for the golf cart application, which is strictly a deep-cycle use with severe rates of discharge and frequent re-charging - very much like typical RV usage.  Most 12V deep cycles are modified automative starting batteries, which are designed for much different usage, basically to deliver very high rates of current (amps) for a few seconds and then "rest" for quite awhile.  Generally they do not hold up anywhere near as well as GC 6V's in RV applications.  You can expect 2-3 years of use from the typical 12V deep cycle, but the typical GC 6V will deliver 5-7 years of use.

Batteries which use AGM technology (as opposed to wet cell) are better suited to deep cycle applications and last longer, probably 1.5-2x as long. However, an AGM battery is also about twice the price of an equivalent wet cell.  However, you never have to check/add water to the cells and an AGM can be mounted in an enclosed compartment (it does not give off hydrogen gas). AGM batteries come in the same sizes as wet cells and deliver about the same amp-hours in any given size.

All this is generalities. You will hear of RVers who got 5 years from their 12V's and others who wore out 6V's in 2-3 years.  A lot depends on your charging system, maintenance (monitoring the water in the cells), and individual usage.
 

John From Detroit

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Ned said:
The rate of discharge of a battery is a function of the load, not if it's a 12v or 2 6v in series.

Actually, I think you are both right... Another poster posted the capacity of different batteries.

A pair of six volt GC batteries in serries is about 220 amp-hours, so a one amp load in theory (Yes I know this is not quite exact) would take 220 hours to discharge it

A pair of Type 24 12 volt batteries is about 170 amp-hours, so a 1 amp load will total them in about 170 hours.

Plus there are other advantages to golf cart batteries.
 

Ned

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The RATE of discharge will be exactly the same for the same load on either type of battery.  1A at 12V is the same if the 12V comes from one 12V battery or 2 6V batteries in series.  The OP didn't ask about the capacity, just the rate.
 

John From Detroit

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Ned said:
The RATE of discharge will be exactly the same for the same load on either type of battery.  1A at 12V is the same if the 12V comes from one 12V battery or 2 6V batteries in series.  The OP didn't ask about the capacity, just the rate.

I agree with that Ned, 1 amp is 1 amp.

However 1 amp hour (which is also 1 amp hour for the record) is less than 1/2 of one percent of a golf cart battery.... But well over 1 percent of a type 24 and about 5 percent of my jump box battery (22 amp hour battery, I just replaced it)

You are talking "Rate of discharge" and he's talking "time till discharged"  for the same load a battery with more amp-hours takes longer to reach the "Discharged" level, and that's where the GC batteries beat many 12 batteries


That said I had a driver try to tell me his tow truck was a 36 volt system because it has 3 12 Volt batteries

Right... In parrallel
 

Ned

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John,

I've also heard that the two 6volt wired in series will discharge at a slower rate then 12 volt batteries.

The original question was about RATE of discharge so that's what I addressed.
 

John From Detroit

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Ned said:
John,

The original question was about RATE of discharge so that's what I addressed.

Right, but he misused the term, you are talking the rate in amphers and he's talking the rate, in percentage for a given load

1 amp is 1 amp, and one amp hour is one amp hour. but one amp hour may be a small, or large percentage depending on the batttery and it's the percentage one amp hour represents that he was asking about.  He just used the wrong term
 

Ned

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I like to believe that people mean what they say and not impute meaning into their words.? Since he didn't correct me, I assume he meant what he said.? I'm sure he's gotten more information from this thread than he expected.? 'Nuff said.
 

daveem

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ive been away from any computer for a couple of weeks, and youre right, I did totally get more information than I ever thought Id get.  Thank you for the response.  I think I will go with 2 - 6V.  Ive been running with a dead cell in my one 12V all summer, and starting to get pretty frustrated. 
Excellent site, and thanks again

;D
 

Ron

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Glad you got the information you were seeking.  This is a great source for RVing information.  Looking forward to your continuing participation.
 
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