Choice of Batteries - Which Would You Choose?

[Makin__Do]

Need expert advise from those that know batteries best. I have an 05 PW Excel that has room for just one 12v house battery in the outside compartment. It's a wet cell, and just as soon get away from them and go to an AGM battery. My plan is to purchase two 6 volt AGM's and place them inside under the galley sink. That's the easy part. The hard part is which brand AGM to go with. My first choice would be Lifeline GDL-4CT6 batteries with 220ah. $600 for two delivered. But, looking around I came across a lesser known name, Amstron. At 210ah and $417 for two delivered at the same weight as the Lifelines and the same specs, other than ah's, I'm wondering if this isn't a case of you get what you pay for or do the Amstrons cost less just for being a lesser known name? If you had a choice and could buy either one, which would you choose?

[MEXICOWANDERER]

CHEATER!
Gel never was ready for RV prime time if they have to be paid for. Unforgiving as a peroxide blond fishwife. That being said I need one for a 190 LED battery spotlight. But gel needs goose-stepping grade operation and maintenance strictness.

[beemerphile1]

To muddy the waters further, I have group 24 MKBattery (East Penn) gel batteries.

In general they are heavier than AGM and flooded, have slightly less AH but the best part is --- I get them free! They have a list price of $275 each but I get them when retired from mobility scooter use at 12 months age.

I can't get a lot of them, I wish I could because I'm sure I could sell them to other RVers.

[MEXICOWANDERER]

Dollars per oz. The group 34 AGM ANYTHING is a ripoff. 160% of the price of a 31.

With my Lifelines, each battery can gulp 100+ amperes charging and not burp. Each battery. 200+ amperes total. So if your choice is Lifeline and your generator can handle 100+ amperes of charge rate, don't be shy about getting a 100 amp charger. Senor BFL13 is very well versed in this.

Another point entirely missed by our enthusiasts is that indoor batteries are far less prone to temperatures that need charging voltage correction. You aren't likely to suffer 30F nor 100F temps inside your rig.

I am sooooooo disgusted with my group 34 flooded engine battery in my toad that it is going bye-bye. A hundred dollars more buys a Lifeline 31 for the trunk. One gauge cable is plenty for the ND gear reduction starter. It's 3KV rated cable and it's going to be inside nylon spiral wrap.

The 11" tall Lifeline group 31 (I call it the 2-story) is an excellent value for $380. Only two terminals to deal with. Be SURE to have a 120 amp circuit breaker alongside the battery. I can recharge my battery in an hour an a half. Keeps gen runtime to a minimum.

[westend]

Somewhere along the electrical upgrade path, the OP should find that being able to connect all of his batteries together will be beneficial.

[pnichols]

Makin' Do wrote:
For me I'm going with AGMs for two reasons,(1) I'm placing the batteries inside the coach and don't want to worry about out gassing (2) I hate wet cell batteries since you always have to be checking the fluid.

Good decision! We've found our AGM RV batteries to be "set it and forget it" RV batteries.

You neglected two more reasons to go with AGM batteries, (3) metal around AGM batteries doesn't get corroded from acid fumes and, (4) AGM batteries charge faster with whatever charger you're going to use on them.

[Makin__Do]

As the OP, let me say thanks to all who have responded and the great info and opinions that are being shared. Those that are battling with all the tech stuff and trying to prove or disprove a point I believe are having a good time. Most of it's over my head, but I am learning.
For me I'm going with AGMs for two reasons,(1) I'm placing the batteries inside the coach and don't want to worry about out gassing (2) I hate wet cell batteries since you always have to be checking the fluid. Now, having said that, I'm keeping my 12v wet cell in the outside compartment (it's only one year old) and leaving the current "house" system intact. The two AGM's will power a second system that runs a new Engel DC fridge and a PlatCat catalytic heater (that's on order). The AGMs have a new separate PD9245C converter.
Some will without a doubt wonder why two systems? Again, I'm just going to leave the current system as is since the outside compartment can only hold one group 34 battery, a short coming of the Excels.I spend 98% of my time in Nat'l Parks, US Forest areas or state parks that have no hookups. Like to stay warm and keep my food cold. Don't use the microwave or furnace and draw the battery. I figure this is a good option. Next, when the wife isn't looking, I'll add solar panels and a controller. And that will be for another post.
Now my choice for the AGMs, based on the input from all of you, and thanks again, will be either Lifeline or Fullriver.

[MEXICOWANDERER]

"Every car you listed had a vent system. The problem is aftermarket cheap batteries did not support most vent systems"

Ain't it a hoot? I did price an OEM Bosch replacement battery in 1966. SIXTY THREE DOLLARS! Maybe .001% of the VW's in the world had vent capable replacements fitted. So they spent 10 years (or a lot more than that) with unvented batteries.

An unvented FIVE PERCENT ANTIMONY battery in a small AIRTIGHT space is bad enough. Now factor in antimony poisoning of the negative plates, 3rd world maintenance, and all the rest and it becomes a joke. Not the VW issue. The comparison between that and using a recombinant AGM inside an RV.

What is NOT funny is lead poisoning of children with ridiculously out of whack VW beetles. Generator charging frequently exceeded 15.0 volts. Batteries remained far past their lifetime and the inside of many beetles looked like junkyard rejects, and smelled like a hot springs.

I do wish lead would go away except perhaps for stained glass window construction. But this is a long way from dancing and shouting that lead is near radioactive in lethality, therefore any potential source of it must be kept out in the barn. In Mexico Chupacabras lurk, in the USA old ladies look under the bed, and alarmism is a moneymaker and hot topic. Always. Unsafe at any speed killed the Corvair, while VW's continued to spin on their top. Common sense? Shirley You Jest!

[MEXICOWANDERER]

And here I thought this was about an EQUAL number of cells.

Yes "I" is a factor. But the amount of skewing present via electrolyte density, plate paste formulation et al makes discussion a moot point. A dense paste greatly reduces CCA potential in favor of longevity. The loss factor can exceed 500%.

Quantifying a scrubber 6-cell battery versus a GC200 3-cell which have similar plate dimension is useless because of electrolyte ratios.

So trying to qualify a 3-cell versus a 6-cell erosion ratio by amperage alone has so many pitfalls it isn't funny. Millimeter by millimeter a GC plate is several hundred percent more resistant to erosion than a 6-cell RV battery.

Complex formulas are designed to show plate porosity versus active electrical value projections. They seldom work in agreement to calculations. Again, theory gets smacked around by reality. To put it bluntly, porous plates suck for cycling duty. And lifespan. But they render awesome CCA. Reminds me of Mexico adding 4+ grams of tetraethyl lead to Super Mexolina gasoline to get octane level to 90 research points.

Compare weight of the batteries versus CCA needed to fire off a high wattage microwave. What qty. lbs of 6 cell batteries do successfully, 3-cell batteries struggle and often fail to do the task. It's a trade-off. A compromise.

If eight or ten 6-cell batteries were paralleled, trying to equalize plate erosion rate (factor) to a pair of 3-cell GC batteries, success might be at hand. But total wattage from each would have to be identical. This is intelligent?

It would be a lot simpler if 3 cell and 6 cell construction were the same. But they aren't. My Rolls bank has to have the least porous plates on the market. CCA and amp hours versus per pound of weight is atrociously low. But .330" plates or not, 20+ years of lifespan does not jibe with solely plate thickness calculations. It has to be something else besides thickness. It's active surface porosity. Less porosity means less geometric adhesion points for sulfates. Harder to hard sulfate, easier to desulfate.

PRICE
PERFORMANCE
LONGEVITY
WEIGHT

Oh well, no one ever claimed a person can have it all. Oops. Forgot about Tarlek.

[westend]

Some AGM recombinant batteries are specified for use indoors, like medical facilities or data centers.

Plate thickness in 6V batteries is directed by the use and frequency of charge/discharge cycles. The thicker plates will endure longer than thinner ones. It is not designed to "catch up" to be like a 12V.

[pianotuna]

Hi Phil,

An 8 D compared to series six volts.

Cell count is the same.

Resistance will slightly higher in the series six volts.

Amperage will essentially be the same if the cell count is the same. The weakest cell will limit the amperage available.

If, instead, there are two 12 volt jars, then amperage will be about 50% lower per cell. Amperage will not be limited to the weakest cell.

I'd still die and go to heaven if I could afford 2 volt jars in the region of 1000 amp-hours each.

[pnichols]

MEXICOWANDERER wrote:
Whats with the Watts? Most RVs use 12 volts - don't know of many that use 8, 6, or
2, volt systems.

David ... draw a simple diagram of two 6V batteries in series and two 12V batteries in parallel.

You'll then easily see that each 6V plate needs to carry twice the current that each 12V plate needs to carry, hence more mass is needed in 6V battery plates if they're going to last as long as 12V battery plates.

That is ... if you agree that current flow over time is related to battery plate erosion rates in flooded lead acid batteries.

[MEXICOWANDERER]

Whats with the Watts? Most RVs use 12 volts - don't know of many that use 8, 6, or
2, volt systems. Some of the old time home inverter systems used an incredible 60 2-volt cells in series. I serviced such a setup a few hundred miles from here that had a 1980's 10,000 watt inverter and more than forty solar panels strung all over the roof and outbuildings.

With regard to spying on internal battery secrets of the AGM

It is a formula involving total weight, ampere hours and CCA. Given same construction (same manufacturer), if the weight of a single 6-cell equals a pair of 3-cells, and CCA (15-second ampere load test) are the same, then plate thickness has to be the same with both batteries.

I do not know how many folks here have played with recombinant VRB batteries. But it takes a lot of effort to get the tiniest amount of venting to occur. Venting is temperature sensitive and reactive with voltage values.

See the emergency lighting in public and private buildings? All of them rely on recombinant flooded VRB. Lead acid batteries. And a flooded battery WILL VENT BEFORE AN AGM WILL VENT.

Any unattended and un-monitored battery under charge is a risk. Severely overcharged, a bank of batteries beneath a motorhome living space (in a compartment) has a potential if severely overcharged to emit enough hydrogen and oxygen to become extremely dangerous if a source of ignition is presented. A lot of if's but if the wheel of luck roulette stops at 100,000,000 to one odds, the top half of the motorhome will violently separate from the bottom half.

Hypothesis cannot rule common sense deductions. I am trying to POUND IN THE POINT that a recombinant battery is not an IED. They can be safely ensconced within an RV, if reasonable precautions are taken to ensure reasonable security. No junk converter chargers, no unsupervised manual charging. Protection against unlimited short circuits (which will blow any battery recombinant caps, a hyper super duty ventilation system right through the roof of the rig).

Yeah I blew up lots of batteries on purpose. KA-POW! Flooded. AGM, NiCad (no NiMH). Calcium calcium, you name it. Messy. I had to worry about Pb flying off the concrete containment pad. Lead exposure of employees and the public. So I had to stop. But I did learn that abused batteries that electrolysized a majority of the H2O from a cell risked an INTERNAL battery explosion that tore the case apart and spewed boiling hot 2.300+ specific gravity electrolyte a considerable distance. Ever see a battery's internals? There is infinitely more "room" inside an electrolyte vented battery than inside a tightly packed absorbed glass mat battery.

If this does not render this issue in perspective I freakin' give up.

[pnichols]

2oldman wrote:
There is no single 6v battery in his treatise.

Right you are.

When taking a more in-depth look: Each cell of the six cells within two 6V batteries in series must pass 8 amps for the series string to put out 8 amps ... while each of the twelve cells within two 12V batteries in parallel must pass only 4 amps for the parallel string to put out 8 amps.

I think I stand by my assertion that 6V battery cells must have thicker plates than the equivalent power 12V battery cells in order for the 6V battery cells to last as long as the 12V battery cells.

Draw a diagram of both configurations - include showing the individual cells in each battery - to see what I'm talking about. It's pretty obvious when looking at a diagram.

Hence, 6V volt RV batteries may not be "better" than 12V RV batteries merely because the 6V battery plates happen to contain more mass.

[red31]

there is a single 12v though, compare 2x6 cells in parallel to 2x3 cell series