battery choice

[pianotuna]

Hi,

I am in analysis paralysis.

I will be purchasing AGM jars.

Here are my two choices:

AGM L-16 Surrette 400 amp-hour six volt with 0.145 plates cost $520 plus tax and shipping Four are needed.

AGM group 27 but group 31 plates 120 amp-hours twelve volt with 0.118 plates cost $230 each plus tax and shipping. I have room for seven.

Charging sources are:

magnum inverter charger @ 125 amps max
progressive dynamics 40 amp
alternator
256 watts of solar with a blue sky 3024di controller.

Which would you choose?

Why?

[NinerBikes]

MEXICOWANDERER wrote:
Concorde revealed that a 13.4 volt float (25C) is perfectly acceptable for their batteries. There is no magic tutti-frutti recipe for their batteries. They are not going to overcharge while other brands thrive.

Concorde POSITIVELY MUST be cognizant of maintenance voltage value conflict between Mil-Spec recommendations and consumer user manual recommendations. A sharp eyed GAO analyst would spot it in a minute and call Concorde on the carpet.

It took me awhile to figure this out.

When I built a Velcro retrofit simultaneous 24/12 volt 100-amp alternator for Edwards AFB, I was faced with over a hundred pages of documentation and specification corroboration (When was the last date your alternator test bench ammeter was factory calibrated?).

No engineer in their right mind is going to challenge my statement that electrical charging and maintenance values cannot possibly differ by any significant value between AGM battery brands. Yes, impedance may differ, but that is a charge acceptance value. But NOT bulk charge maximum or float voltage values. I will draw blood from any engineer's gluteus maximus who dares argue this statement.

THOUSANDS OF MOTOR VEHICLES ARE RUNNING AROUND WITH HUNDRED SIXTY DEGREE F AGM BATTERIES OPERATING AT 14.0 VOLTS AND THE AGM BATTERIES ARE LASTING FOR MANY YEARS. This reality check should make an impression on gullible consumers who swallow face saving "Not Me Too" Engineer (salesmen) individualist's personal-touch pronouncements for AGM battery floating guidelines. This relies on good old-fashioned common sense.

The AGM battery in the Touareg TDI sits underneath the drivers seat, away from blasting DPF regeneration temperatures which are like igniting charcoal briqquets that are glowing orange by fanning them like a mad man with excessive turbo boost to get plenty of oxygen to get the black carbon particles to flame and burn off.
My scan gauge 2 says they charge at 14.0 to 13.8V all day long.

The Germans try to keep it behind the firewall, not in front of it, in their nicer car designs.

[JiminDenver]

MrWizard wrote:

JiminDenver wrote:
I've been following the thread since batteries are next on my list. (if it ever stops raining)

So what I am seeing is that my array capable of close to 50a is too wimpy for AGM's, right?

My array is less
And could be considered wimpy by that standard
What I do is run the genset in the morning let it do the heavy lifting coffee maker and MW and heavy amp charge
Then let the solar handle it until supper time
When I run the genny again

We full-time do that is a major thing
You can let your solar charge the batteries between trips, if you want too, nothing wimpy about 50 amps charge, just because the battery chemistry will let them take more

I had 490w last year and the 34a peak wasn't wimpy. Had they been polys I would still have 490w. I was referring to seeing that the "need" that kind of amperage. The plan is to at least snowbird someday and believe me after the last few months here in Colorado, we will be taking a generator. I'd hate to run it but it could power the 55a parallax while the solar does it's part. That would be 90-100a or so in good light. 70a under cloudy conditions.

[MEXICOWANDERER]

Gotta keep it in perspective. For example Concorde does not want their lifeline charged at 10 amps or 10% amp hour value. The tipping point seems to be when incomplete charge is performed repeatedly.

This was the answer to the giant "Duh?" I had to hammer into the heads at Optima several years ago. They didn't want to believe it but the poor engineer I fought for thee hours on the phone to talk to, heartily agreed. That phone call revealed the monkeys were running the zoo. Sadly, it's the same all over. I chatted with Rolls a few days ago and it took me two tech questions to reveal I was talking to an applications engineer. Real engineers are locked in the dungeon under the watchful eye of The Knight Of The Realm. I must have signed six dozen non-disclosure agreements (get this - they were 99-year contracts!) Without exception they are strict - I am forbidden to reveal the nature of the tests I performed never mind the results. Those knotheads can issue injunctions, summons, which if violated, can lead to arrest warrants, denial of passport, on and on. Battery peddling is a bare-knuckle business. They take things seriously.

[MrWizard]

JiminDenver wrote:
I've been following the thread since batteries are next on my list. (if it ever stops raining)

So what I am seeing is that my array capable of close to 50a is too wimpy for AGM's, right?

My array is less
And could be considered wimpy by that standard
What I do is run the genset in the morning let it do the heavy lifting coffee maker and MW and heavy amp charge
Then let the solar handle it until supper time
When I run the genny again

We full-time do that is a major thing
You can let your solar charge the batteries between trips, if you want too, nothing wimpy about 50 amps charge, just because the battery chemistry will let them take more

[pnichols]

jrnymn7 wrote:
Drop 13.8v to 13.2v using a simple buck converter. No biggie.

Nope.

Our AGMs are direct connected to the coach's Parallax converter .... the AGMs have been both floated and most-of-the-time charged from the same converter model since around 2007. ( I had to replace the converter early-on under warranty, years ago.)

[MEXICOWANDERER]

Nor deep discharges. It all fits when you think about it. Deep discharges, fast recharges, starting pulses, and a 140 amp alternator zaps the battery. Think it through. If it didn't doesn't add up there would be well publicized issues arising.

Continuous deep cycling is the triathlon test of any battery. Over and over and over cycling to 50%. Very high total kWh usage.

A wide range of float voltages is positively necessary to fit the construction of flooded batteries. There are 1%, 2.0%, 2.75%, and 5% antimony alloys. Antimony calcium (hybrid), and a plethora of electrolyte densities. No way on earth is a single float voltage value valid for this range.

But AGM is 99% minimum pure lead, with minor amounts of calcium, and silver. Electrolyte is almost universally 1.300 density. If they should space plates and mats far enough apart to affect chemistry it would have a severely negative impact on impedance, therefore performance. Coil plate batteries are not part of the universe so I ignore them. My car does not leap 15-foot arroyos and I do not wear a three point safety harness.

[jrnymn7]

Drop 13.8v to 13.2v using a simple buck converter. No biggie.

[pnichols]

MEXICOWANDERER wrote:
I was faced with over a hundred pages of documentation and specification corroboration (When was the last date your alternator test bench ammeter was factory calibrated?).

I hear ya.

If you think that documentation is a bit much ... try managing a crew that's responsible for instrumenting, lighting up, and running to solid fuel burnout ... Minuteman 1st/2nd/3rd stage booster engines in the desert for a few years. After each automatic calibration, the instrumentation accuracy was maintained with circuit resistors costing the taxpayers around $100 apiece (back then) ... and we had hundreds of them in the spare components inventory. The whole thing was a paperwork headache.

Sooooo .... I guess you're maintaining that it would be OK for me to float new Concorde AGM batteries at ~13.8 volts when they recommend only ~13.2 volts? This would then be float-treating any new Concordes I buy the same way I have been float-treating my Interstate AGMs at ~13.8 volts all these years. It seems to me that'd be a bit harsh on Concordes. :h

[jrnymn7]

And I highly doubt those AGM's in automotive use are seeing 10% charge rates, either.

[MEXICOWANDERER]

Concorde revealed that a 13.4 volt float (25C) is perfectly acceptable for their batteries. There is no magic tutti-frutti recipe for their batteries. They are not going to overcharge while other brands thrive.

Concorde POSITIVELY MUST be cognizant of maintenance voltage value conflict between Mil-Spec recommendations and consumer user manual recommendations. A sharp eyed GAO analyst would spot it in a minute and call Concorde on the carpet.

It took me awhile to figure this out.

When I built a Velcro retrofit simultaneous 24/12 volt 100-amp alternator for Edwards AFB, I was faced with over a hundred pages of documentation and specification corroboration (When was the last date your alternator test bench ammeter was factory calibrated?).

No engineer in their right mind is going to challenge my statement that electrical charging and maintenance values cannot possibly differ by any significant value between AGM battery brands. Yes, impedance may differ, but that is a charge acceptance value. But NOT bulk charge maximum or float voltage values. I will draw blood from any engineer's gluteus maximus who dares argue this statement.

THOUSANDS OF MOTOR VEHICLES ARE RUNNING AROUND WITH HUNDRED SIXTY DEGREE F AGM BATTERIES OPERATING AT 14.0 VOLTS AND THE AGM BATTERIES ARE LASTING FOR MANY YEARS. This reality check should make an impression on gullible consumers who swallow face saving "Not Me Too" Engineer (salesmen) individualist's personal-touch pronouncements for AGM battery floating guidelines. This relies on good old-fashioned common sense.

[pnichols]

Mex,

The only non-cost issue ... for some of us ... with those Concorde AGM jet plane batteries is their recommended 13.2 volt float voltage.

I'm afraid a good old converter and/or an improperly set up solar controller's output would slowly but surely cook them.

If this is not the case, then Concorde literature needs to change it's recommended float voltage from a fixed value to a range of values - and fast - before I buy new Group 31 AGM batteries in a few weeks prior to our upcoming trans-U.S. RV excursion.

If anyone wants to buy our "probably still pretty good" ~9 year old twin 100 amp hour AGM batteries ... let me know (just kidding ... to the recycling center, sadly, they'll probably go).

[MEXICOWANDERER]

IMMHO it would be good for 200 amp hours if you could completely charge the bank daily. This is where a 70 amp generator charge for one hour then solar for the remaining would be ideal. My electro-chemical curiosity is whispering to me that sufficiently high amperage somehow ionizes the plate surface making it more affable to return sulfates to the acid saturated mat.

By the way, Mil-Spec requires an insane amount of documentation using NIST registered test equipment, and clearly defined test protocols with corroborative definitions.

To the best of my knowledge Concorde is the solitary OEM that utilizes these protocols on their consumer products. Their AGM batteries power military aircraft including the B2 and F34 craft. I weep when I see the cost of their group 31-T batteries, but weeping is healthier than raging when a 135 dollar Wal-Mart flooded 31 turns out to be near worthless. What's cheaper, a three hundred fifty dollar battery every ten years or four, hundred and thirty five dollar batteries, plus the warranty chase gasoline and destroyed vacations, or alternative energy usage? Penny-wise and dollar stupid...

[JiminDenver]

I've been following the thread since batteries are next on my list. (if it ever stops raining)

So what I am seeing is that my array capable of close to 50a is too wimpy for AGM's, right?

[jrnymn7]

"or Hung Chow, special."

dang, I nearly spewed my coffee all over my laptop, lol!