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 > Two 6 volt batteries or two 12 volt batteries ??

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lawrosa

Horry County

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Posted: 02/04/18 01:50pm Link  |  Quote  |  Print  |  Notify Moderator

Fishhunter wrote:

This discussion brought up a question I've been wondering about..if your TV is plugged into the TT you can run off the TV batteries...will this also charge the TV batteries when the TT is plugged into AC or running off generator?


Yes. as long as there is no disconnect feature on the truck. My 7 pin is live all the time.

That is where my third battery comes from.. My truck has a camper/accesorie package and uses a battery just for the 7 pin. I have a seperate starting battery.

So when boon docking my truck is always plugged in. My solar and or gen will charge the truck battery too along with RV batts.

I can get a bit over 15 amps through the 7 pin if I needed to charge the RV batts from the truck. On the chevys of my year too the ECM controls the volts and I get 14.5 volts at the 7 pin.

Just a note there is an isolator that seperates starting and aux battery..


Mike L ... N.J.

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time2roll

Southern California

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Posted: 02/04/18 01:51pm Link  |  Quote  |  Print  |  Notify Moderator

Fishhunter wrote:

This discussion brought up a question I've been wondering about..if your TV is plugged into the TT you can run off the TV batteries...will this also charge the TV batteries when the TT is plugged into AC or running off generator?
Depends if the truck has an isolation relay to stop the backfeed. Ford does have a relay.

I use a Trik-L-Start combiner over the relay to allow my trailer solar to keep my Ford truck battery charged in storage.


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Gdetrailer

PA

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Posted: 02/04/18 01:52pm Link  |  Quote  |  Print  |  Notify Moderator

FrankShore wrote:

One 6v goes out and you're in trouble.


One CELL of a "12V" shorts and you are in trouble..

One shorted cell of one 12V battery when in parallel will discharge the "good" battery and will also prevent the "good" battery from recharging properly.

One 12V battery gets "weak" and the OTHER 12V battery takes a beating until BOTH no longer work.

The problem with your "theory" is the mere fact that MOST CONSUMER "12V" batteries are actually COMBINATION "starting/deep cycle" batteries which are marketed as "RV/Marine" batteries.

RV/Marine batteries are a COMPROMISE, they are designed to take the demands of high current for a short time (starting) and the demands of deep discharge (trolling motors) for a longer time than just a starting battery.

As a compromise they HAVE some drawbacks.. They do NEITHER "job" well.

They don't function as well under "starting" or a deep cycle.

IE, they don't last as long as a standard car battery in starting mode or can be deeply discharged as a real deep cycle.

A group 27 RV/marine battery has about 70 Ahr of capacity, of that you only want to use no more than 20% (14 Ahr) of that capacity for longest battery life but can be discharged to 50% (35 Ahr) at a REDUCED LIFE.

Granted, you can find true 12V deep cycle batteries (group 31), the draw back to those is not every battery shop carries them (special order) and since they are not in super high demand they ARE considerably MORE EXPENSIVE.

Hence the reason as to why 6V Golf Cart batteries are a great alternative..

6V GC batteries ARE a true deep cycle, ready available and extremely low cost per Ahr.

Typically 6V GC batts give you about 210 Ahr of capacity per pair and you will need two of these wire in series (pos of on to the neg of the other).

6V GC batteries ARE designed to be able to withstand up to 80% (168 Ahr) discharges but for max life should be limited to %50 (105 Ahr).

It would take THREE group 27 RV/marine discharged to 50% to equal one pair of 6V GC batteries at the same 50% discharge.. However the life of the group 27 12V RV/marine batteries WILL be considerably LESS and you end up spending MORE on the THREE RV/Marine batteries over the life of your RV.

If you don't boondock, then no reason to buy GC batts, but if you do boondock, you WILL get much more capacity and it WILL cost you less in the long run.

I don't boondock but I did convert my TT to a residential fridge so one pair of 6V GC batteries can easily run my fridge, some lights and even the furnace for 24 hrs before needing to recharge. It would take at least three if not four group 27 RV/marine batteries to do the same job and the service life will be much shorter..

I just replaced my first set of GC batteries this spring, the first set gave me 9 years of service and they were still working OK but I did notice that they had lost some capacity so I replaced them.. Not bad service and the replacements cost $80 each at Sam's.

centerline

Salem OR

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Posted: 02/04/18 02:14pm Link  |  Quote  |  Print  |  Notify Moderator

RasMouSein wrote:

I have industrial "true" deep cycle 12v... 2 for a total of 430amp/h...
The local battery shop had a deal a the time, so it made sense for me.
People go for the 6v because (story goes) of the footprint, they tend to be taller and fit in the same rack. Therefore more amp/hour in the same place.


I agree... but it may not be for everyone due to cost... but you cant get something for nothing!

I also went with the true deep cycle 12v batts (US185HC) for a total of 440ah.... and the footprint is the reason.
I have room for 3 batteries and 3 6v batts just dont work in a 12v system... I only have 2 batteries at this time, but I have room for another 220ah if I decide I want it... (total of 660ah)

with 2 LARGE 6v batts, (L16HC) my limit would have been around 370ah...and not allowed for any option for continued use if 1 of them failed while out and away, whereas with 2 12v batts, the bad one can be removed from the system, and you can still carry on with the good battery... IF I had room for 4 batteries, I probably would have installed 4 6volt L16 batteries.

BUT, when one is looking at regular RV sized batteries, 2 6v batts have the ability to give much better performance over a longer period of time, than does the "regular sized" 12v multipurpose battery that is somtimes called "deep cycle" by those who dont know any better...


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rbpru

North Central Indiana

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Posted: 02/04/18 02:46pm Link  |  Quote  |  Print  |  Notify Moderator

Well the OP has lots of good advise but it all comes back to what his goals are and his usage.

We do not boondock in the true sense but we will spend a day or two without electric if we need to. I have a four day event every years so I just tote my trolling motor battery to carry me over the last day or so.

I works fine for the once or twice a year I need extra battery power. If I needed it more often I would go with two 12 volt batteries and a transfer switch.


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2oldman

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Posted: 02/04/18 03:05pm Link  |  Quote  |  Print  |  Notify Moderator

KD4UPL wrote:

This gets discussed to death about every couple weeks. If you search the topic you could find enough reading material for years.
Done.

6v v 12 2017
6v v 12 2017
12v vs 6v.. which charge faster? 2014
12v or 6 Dec 2013
2- 12v or 6v June 2013
12v vs 6v batteries 2013
12v vs 6v batteries 2006
More 12v vs 6 2006
12v vs 6v 2010
Why 2 6? 2006

Sandia Man

Rio Rancho, NM

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Posted: 02/04/18 03:25pm Link  |  Quote  |  Print  |  Notify Moderator

We prefer boondocking and have done so extensively since getting our current rig over a decade ago. Upon purchase we had the dealer install a pair of 12 volt rv/marine batteries that appeared to do a decent job of providing power when we were RVing off the power grid, after a couple of years they were not bouncing back like they had before, we went to Samsclub and picked up a pair of 6 volt GC2 batteries for $60 a piece.

Same smart converter charger, same built-in genny, didn't notice a drop off in performance for 7 years. Gave them another year of use and just replaced them last season for another set of GC2 batteries where we paid $80 each. I guess 8 or so years from now when I need batteries again they may cost nearly $100 each, without a doubt the best bang for your buck if you plan to run them hard like we do.

FrankShore

Laguna Beach, CA

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Posted: 02/04/18 03:56pm Link  |  Quote  |  Print  |  Notify Moderator

Gdetrailer wrote:

FrankShore wrote:

One 6v goes out and you're in trouble.


One CELL of a "12V" shorts and you are in trouble..

One shorted cell of one 12V battery when in parallel will discharge the "good" battery and will also prevent the "good" battery from recharging properly.

One 12V battery gets "weak" and the OTHER 12V battery takes a beating until BOTH no longer work.

The problem with your "theory" is the mere fact that MOST CONSUMER "12V" batteries are actually COMBINATION "starting/deep cycle" batteries which are marketed as "RV/Marine" batteries.

RV/Marine batteries are a COMPROMISE, they are designed to take the demands of high current for a short time (starting) and the demands of deep discharge (trolling motors) for a longer time than just a starting battery.

As a compromise they HAVE some drawbacks.. They do NEITHER "job" well.

They don't function as well under "starting" or a deep cycle.

IE, they don't last as long as a standard car battery in starting mode or can be deeply discharged as a real deep cycle.

A group 27 RV/marine battery has about 70 Ahr of capacity, of that you only want to use no more than 20% (14 Ahr) of that capacity for longest battery life but can be discharged to 50% (35 Ahr) at a REDUCED LIFE.

Granted, you can find true 12V deep cycle batteries (group 31), the draw back to those is not every battery shop carries them (special order) and since they are not in super high demand they ARE considerably MORE EXPENSIVE.

Hence the reason as to why 6V Golf Cart batteries are a great alternative..

6V GC batteries ARE a true deep cycle, ready available and extremely low cost per Ahr.

Typically 6V GC batts give you about 210 Ahr of capacity per pair and you will need two of these wire in series (pos of on to the neg of the other).

6V GC batteries ARE designed to be able to withstand up to 80% (168 Ahr) discharges but for max life should be limited to %50 (105 Ahr).

It would take THREE group 27 RV/marine discharged to 50% to equal one pair of 6V GC batteries at the same 50% discharge.. However the life of the group 27 12V RV/marine batteries WILL be considerably LESS and you end up spending MORE on the THREE RV/Marine batteries over the life of your RV.

If you don't boondock, then no reason to buy GC batts, but if you do boondock, you WILL get much more capacity and it WILL cost you less in the long run.

I don't boondock but I did convert my TT to a residential fridge so one pair of 6V GC batteries can easily run my fridge, some lights and even the furnace for 24 hrs before needing to recharge. It would take at least three if not four group 27 RV/marine batteries to do the same job and the service life will be much shorter..

I just replaced my first set of GC batteries this spring, the first set gave me 9 years of service and they were still working OK but I did notice that they had lost some capacity so I replaced them.. Not bad service and the replacements cost $80 each at Sam's.

I didn't have a "theory"


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FrankShore

Laguna Beach, CA

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Posted: 02/04/18 04:11pm Link  |  Quote  |  Print  |  Notify Moderator

lawrosa wrote:

FrankShore wrote:

One 6v goes out and you're in trouble.


Yes. In that instance your options are.

1. Go out and buy another battery. You can find 6 volts without much trouble locally.
2. Disconnect the batteries and run the RV off the tow vehicles battery temporarily to get you through the weekend.
3. disconnect batts and Run off generator to get you through.


When I'm on the boat, it isn't just a "run off the tv or run off the generator" situation. That's why I always use Lifeline AGM's in both.

Gdetrailer

PA

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Posted: 02/04/18 04:17pm Link  |  Quote  |  Print  |  Notify Moderator

FrankShore wrote:

One 6v goes out and you're in trouble... snip

snip...I didn't have a "theory"


Umm.. by stating that "one 6V goes out and you are in trouble" you HAVE stated YOUR "THEORY".

Using one PAIR of 6V GC batts in series is no worse than folks using ONE single 12V battery as which MANY folks do.

My previous TT only had provision for one single 12V group 27 RV/marine battery and in the 5 yrs of use it never got me "in trouble".

Not to mention unless you have ventured several thousand miles away from human civilization you can EASILY just go drive to a store and buy replacement batteries and continue on camping.

Minor inconvenience, yes, trouble, not hardly.

The "redundancy" theory that you have posted is really a silly argument that holds no weight.

You drive a vehicle which unless it is a Diesel has but ONE SINGLE 12V STARTING BATTERY.. How many times have you personally been left down by that one single starting battery?

Myself ZERO times and that includes sub zero freezing weather.

I would be more concerned about having a starting battery go dead out in the middle of nowhere.. Walking out of wilderness is often not an option.

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 > Two 6 volt batteries or two 12 volt batteries ??
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