Do I need 4x6v Batteries to replace 2x12v Batteries?

[DaytonaDan]

Hi,

Two quick questions:

Are four 6v Deep Cycle Batteries required if I want to replace the original two 12v Deep Cycle Batteries?

—AND—

Which Brand and Model of AGM 6v Battery is recommended?

Thanks.

[AirMiles]

No, you want two 6V batteries wired in series to replace two 12V batteries wired in parallel. As for brand of AGM battery, most use Lifeline batteries.

[ROBERT CROSS]

No...6v is for golf carts.

Bob
🇺🇸

[fran&frank]

You need a minimum of two wired in series to get 12 volts. However you could increase your capacity by wiring any number of pairs of 6 volt batteries in parallel (but each pair is in series)--Frank

[kscherzi]

Why AGM?

[thewarden]

Originally Posted by kscherzi

Why AGM?

No maintenance, little to no off gassing when being charged. They also tend to be a little more robust than the average flooded deep cycle battery and therefore you can get better lifespan out of them.

[kscherzi]

All true what you say about AGM's, they may last a little longer and have no maintenance. Their electrical performance is about equal.

But consider the price, about $350 each for Lifelines, vs $100 to $150 each for wet cells. Off gassing is not a issue when batteries are stored in an exterior battery box. Maintenance is pretty simple for wet cell, check and add distilled water about once a year. If the batteries must be indoors, then by all means get AGMs.

Just depends on your pocketbook and tolerance for a little more work.

[drbrick]

No - we have 2x 6v Trojan T-105s in series = 250amps works well with our system.

[uncle_bob]

Hi

There is no advantage to 6V batteries vs 12V batteries. You get the same "stuff" either way. The *only* reason to go with this or that is to get a very specific make and model of battery. Simply going to a generic this or that is not what you want to do.

Trojan T-105's *are* 6V batteries. They also are flooded batteries. They are known to be good parts. They do have some unique care and feeding needs to get full performance out of them.

On sale this week at Costco I'm sure you can find 6V batteries from somebody nobody has ever heard of. They are a *very* different item than a T-105.

Bob

[Protagonist]

Originally Posted by uncle_bob

There is no advantage to 6V batteries vs 12V batteries.

Not entirely true. For batteries of similar exterior dimensions, you may be able to get more amp-hour capacity out of two 6v batteries wired in series than from two 12v batteries wired in parallel. But that must be compared on a case-by-case basis, based on what will fit in a given battery box.

For example, two Lifeline GPL-24T 12v batteries (measuring about 11×7×8 inches each) in parallel provide 160 amp-hours rated capacity, of which you can use up to 80. Two Lifeline GPL-4CT 6v batteries in series have similar dimensions (about 10×7×10 inches each), but would provide 220 amp-hours rated capacity, of which you could use up to 110. So in this case, if the taller 6v batteries would fit the battery box, one would have greater amp-hour capacity from the 6v batteries. But as I said, the comparison has to be done anew for each case, based on what 12v batteries one has now, and what 6v batteries will fit in the box as replacements.

On edit: Don't forget that AGMs (if you use them) don't have to sit upright, but can be set on end or on their side if that provides a better fit for the battery box. That may affect the choice of 6v replacement batteries as well.

[AirMiles]

Originally Posted by uncle_bob

Hi

There is no advantage to 6V batteries vs 12V batteries. You get the same "stuff" either way. The *only* reason to go with this or that is to get a very specific make and model of battery. Simply going to a generic this or that is not what you want to do.

Trojan T-105's *are* 6V batteries. They also are flooded batteries. They are known to be good parts. They do have some unique care and feeding needs to get full performance out of them.

On sale this week at Costco I'm sure you can find 6V batteries from somebody nobody has ever heard of. They are a *very* different item than a T-105.

Bob

Both Costco and Sam's Club sell high quality Duracell EGC2 6V golf cart batteries made by Deka East-Penn. These batteries are well made direct competitors of the excellent Trojan T105. Sam's club also sells an "economy" GC2 6V golf cart battery made by Deka East-Penn that I would avoid. Read this article from a marine battery expert that explains how to buy a good deep cycle battery and recommends the Duracell EGC2 6V golf cart batteries: https://marinehowto.com/what-is-a-deep-cycle-battery/ This is the link to the high quality battery that can be bought at Costco or Sam's Club: https://www.samsclub.com/p/duracell-...c2/prod3590220 Trojan also makes some "economy" batteries that I would avoid. All companies make both "quality" batteries and "economy" batteries. Read the above article to learn which are the "quality" batteries.

[waninae39]

IMHO, the direction in trailers as well as auto is Lion battery

[uncle_bob]

Originally Posted by AirMiles

Both Costco and Sam's Club sell high quality Duracell EGC2 6V golf cart batteries made by Deka East-Penn. These batteries are well made direct competitors of the excellent Trojan T105. Sam's club also sells an "economy" GC2 6V golf cart battery made by Deka East-Penn that I would avoid. Read this article from a marine battery expert that explains how to buy a good deep cycle battery and recommends the Duracell EGC2 6V golf cart batteries: https://marinehowto.com/what-is-a-deep-cycle-battery/ This is the link to the high quality battery that can be bought at Costco or Sam's Club: https://www.samsclub.com/p/duracell-...c2/prod3590220 Trojan also makes some "economy" batteries that I would avoid. All companies make both "quality" batteries and "economy" batteries. Read the above article to learn which are the "quality" batteries.

Hi

I know you have had good service out of yours and I don't dispute that. I have a buddy who re-did his boat with East Penn batteries and it was a disaster .....

Bob

[AirMiles]

Originally Posted by uncle_bob

Hi

I know you have had good service out of yours and I don't dispute that. I have a buddy who re-did his boat with East Penn batteries and it was a disaster .....

Bob

Again, all companies make "economy" batteries and "quality" batteries. Your chances of having a good experience are much greater if you start with "quality" batteries. The next problem is even if you buy a "quality" battery, you can get bad batteries. For example, when I bought my Duracell EGC2 batteries, Batteries Plus had a sale on them for about $100 each. I went to Batteries Plus to buy them. The batteries they pulled off the shelf were manufactured one year earlier! I asked the guy to go back to the shelf and find a newly manufactured set. He replied he's not allowed to do that and the old set on the counter was what I had to buy. I walked out, went to Sam's Club, and bought a newly manufactured pair of batteries. I also take my voltage meter when buying batteries and find newest manufactured ones with the highest voltages. Maybe I'm a little anal about choosing my batteries, but maybe that's why some people have good results and some people report disasters.

FYI, on another thread someone posted that Costco has the new Lion Energy 105AH Lithium batteries on sale for $699. That is an awesome battery at a great price. If I were in the market for a set of batteries . . . https://www.costco.com/lion-energy-s...100535965.html

[JayTheCPA]

Will break from Uncle Bob in terms of advantages of one over the other as well. Last I checked there is an advantage to twin 6v batteries in series versus twin 12v in parallel. If one of the 12v batteries starts to die and is weaker than its twin, the weaker battery will pull-down the stronger twin (without a charger providing power to compensate). No biggie if always connecting to shore power, but it will effect boondocking by presenting a constant power leak in addition to native loss. 6volts in series do not do this. Am sure a better expert will correct me if this is not accurate.

[waninae39]

if 2 x6v in series, and one of the 6v is weak, it will reduce the total voltage.

thus the same results

no advantage of 2 x 6v

[AirMiles]

The greatest advantage of 6V batteries is that its easier to find a "quality" 6V golf cart battery. Most 6V batteries are designed to power golf carts. A golf cart needs a great deal of stored energy to power a cart all day around a golf course. Therefore, golf clubs demand "quality" batteries for their golf carts.

The greatest disadvantage of 12V batteries is that its easier to find an "economy" battery in 12V. Most RV & Marine manufacturers want the lowest cost battery to keep their cost down. Therefore, marine and RV manufactures demand low cost "economy" batteries for their applications.

Quality batteries have more lead, so weight is a good indicator of battery quality. Attached is a picture of the lead inside a typical RV/Marine battery versus the lead in a typical 6V golf cart battery from this article: https://marinehowto.com/what-is-a-deep-cycle-battery/ A picture is worth 1,000 words, but I suggest reading the whole article.

The Airstream battery box is designed to fit a pair of "quality" 6V golf cart batteries. A pair of "quality" 12V batteries are unlikely to fit inside the Airstream battery box. Imagine two of those lead-filled 6V batteries from the picture inside the Airstream box. That would maximize the amount of lead that could be placed inside that box compared to two of the 12V RV/Marine batteries in the picture.

[HiHoAgRV]

The advantage that 2x 6 volt batteries have is a reduced chance of failure.

Statistics say that every cell and every connection has a chance of failing. The dual 12v setup has 2x as many cells and 50% more connections therefore a higher chance of something failing. Engineering teaches a class on this and I found it very interesting that it mathematically demonstrated the KISS principle.

My professor used the example of a single engine vs a dual engine aircraft. The twin has twice the parts and a higher chance of failure.

Of course if the single engine fails, it’s going down faster than the twin. I guess the twin you can better select the impact zone!

[ROBERT CROSS]

Originally Posted by HiHoAgRV

The advantage that 2x 6 volt batteries have is a reduced chance of failure.

Statistics say that every cell and every connection has a chance of failing. The dual 12v setup has 2x as many cells and 50% more connections therefore a higher chance of something failing. Engineering teaches a class on this and I found it very interesting that it mathematically demonstrated the KISS principle.

My professor used the example of a single engine vs a dual engine aircraft. The twin has twice the parts and a higher chance of failure.

Of course if the single engine fails, it’s going down faster than the twin. I guess the twin you can better select the impact zone!

So...if one six goes down you WON'T crash fast?

One 12 goes down you can crash....SLOWLY. 🛬

Bob
🇺🇸

[uncle_bob]

Hi

Failure in a battery is a function of the plates. If you have X capacity, you have a certain total plate area. It doesn't matter much how you distribute it, the failure issues are still there.

Bob