Any Morningstar Guru's here?

Old Guy

Thank you.  I didn't think about the 50%.  Learning!

PNjunction

Ah, don't make the mistake 99% of agm owners do:  babying them.

In other words, simplify and run at the very least the 14.4v absorb with NO eq.  That is still on the conservative side.

To keep it even simpler, since your controller does not have a "freshening" setting for agm (swith 8 is software programmed, which you don't have access to I believe), the far simpler solution would be to set the switches to a slightly aggressive 14.6v with no eq, and call it a day.  Your probe will automatically adjust.

Advanced info:  the reason it is better to be slightly aggressive, rather than slightly conservative with an agm is for the following reason:

Most users coming from the flooded world, don't understand that an agm, in order for the recombination process to function properly, means that unlike a flooded battery where the positive and negative plates are equal in capacity to each other, in an agm, the negative plate is slightly *larger* in capacity than the positive.

What that means is that under a normal CC/CV charge routine that always seems to fully charge the battery, eventually the negative plate sulfates, despite following the more simplistic charge regimes mentioned by most manufacturers intended for consumers.

Yet when you consult agm charge regimes intended for industrial users, a "freshening charge", or *slight* overcharge is necessary upon receipt and every 30 days thereafter.  This is about 0.2V above normal agm absorb for 3 hours.  In fact, even Optima's own chargers do this but they call it "conditioning".   Just an example.

So that is why if those were my batteries, I'd run at the max voltage limit allowed - in this case 14.6v absorb.  Lacking a freshening controlled charge for agm with that controller, this is the simplest half-way measure between both worlds.

The other thing is that this is not some el-cheapo agm brand.  It's an East Penn / Deka Intimidator in Duracell clothing.

TIP:  Since you are running two of these in parallel, it is wise to keep an eye out to see if they are getting unbalanced.  Make a voltage measurement across each battery's terminals, and if they are more than 0.1v different from each other, then something needs attention.

That could mean inspecting / tightening the cabling, or perhaps take each one home and put each one on a decent charger *individually* before reassembling back in parallel.  (The Optima charger does a fine job on agm)

Probably too much info but the gist is most agm's are babied to death.

littleharbor2

At what point while riding this 14.6 volt knife edge will your AGM batteries begin to create so much hydrogen gas that they cannot effectively recombine it and begin to "burp" it out?

mcgivor

As I am not, nor claim to be, an expert on AGM, my opinion would be to stick to the closet setting recommended by the manufacturer, not to push the envelope and dance on the head of a pin, so to speak, so with all due respect to the suggestion to run at  14.6V, would be doing just that , my opinion would be the sealed setting @14.35V with a float @13.4V and a boost (EQ) @14.4V, which could be either programed as a monthly event, or conducted manually,would be best suited for this application. The rational behind this is firstly, they are not a true deep cycle batteries  and secondly they are not in daily cyclical use. No offense to anyone or their suggestions implied.

Old Guy

I find this discussion very interesting. I have a rather off topic question....

If I put that same battery in a vehicle they typically get charged around 14.4 volts and have no equalization that I am aware of.  I have had  car batteries last anywhere from 3 to 10 years.  Why are the solar chargers so different?

Old Guy

I think I answered my own question.... I keep forgetting the sunlight is a variable.  

BB.

Also, a car battery is designed and operated to only discharge a maximum of 15%.

No deep cycle operation.

-Bill

PNjunction

Guys - no more than 12 hours at 14.6v.  Better yet, 14.4v will do for a standard lead calcium.

Probably the quickest way to explain it all is to search for the MK Battery (division of East Penn / Deka)
1913 Renewable Energy Charging Parameters pdf document.

Note that is not the year, but just happens to be the number of the document.

Unfortunately, MK has seen fit to lump AGM and GEL together if you look at the charts.  Trust me, stick to the *lower* voltages for gel, which are correct in the Morningstar controller, and found in *earlier* MK documentation.  The gel info conflicts with what East Penn says directly about gel.  Just a warning for gel guys.

Mcgivor - no offense taken.  One should always stay within the manufacturer's recommendations, but remember this:  nearly all the official documentation assumes a steady constant AC power supply source for recharging, and does not take into account variable solar sources!

What you'll discover from that, is that if you don't run close to the edge, while still staying within specs of course, is that you will walk-down or baby your agm with solar rather quickly just because it isn't constant or reliable enough to ensure a full charge all the time.  So one should take *slightly* more agressive measures in this application.

In fact, if one is doing daily-cycling, you should forget float completely!  That's right - simple 2-stage charging and absorb at 14.4v until the sun goes down.  If you don't, and you are daily cycling, you'll walk the capacity down.

It is perhaps the hardest thing to acknowledge - most applications due well by being conservative, but with agm's, just the opposite (provided you don't go absolutely overboard).  Fortunately, lower-cost learner batteries like these will provide the hands-on before investing in a really expensive TRUE deep cycle agm bank.

PNjunction

BB - you are quite right about not deep-cycling a standard flooded SLI battery beyond 15% if you want to demonstrate 3-4 years of cycling.  AGM's, even standard automotive ones can go a bit deeper - with some provisions!

For lurkers, note that I'm not trying to advise anyone to build a serious housebank out of automotive AGM's.  But if you are a casual experimenter, RV'er, weekend-warrior cabin type, the near immediate non-counterfeit availablity, deals and so forth *fresh from reputable dealers*, can be shoehorned into service.

Generally, the breakdown is like this - and this assumes a FULL RECHARGE:

Standard *quality* agm, like an East Penn / Deka Intimidator or equivalent:

DOD 50% - 350 cycles or so.  Do daily cycling, and you'll last maybe a year tops.  Expensive!
DOD 25% - 600 cycles or so.  Getting better.
DOD 12.5% - > 900 cycles

NEVER take a "standard" lead-calcium agm beyond 50% DOD worst case regularly.
NEVER take a "beefed up" lead-calcium (so called deep cycle / marine) beyond 80% DOD *intermittently*

And as BB notes - shallow DOD's are key, although generically the vehicular agm's have twice the cycle life over flooded, half the internal resistance and so forth, mostly due to just the physical way they are made.  No need to go deeper into marketing fluff...

You can see from this that if you pick your operations carefully, (like weekend warrior use), you usage may just outlive the cycle life.  Bench-racers that want to pick apart specs can find these values online.  Since they are not really designed for deep-cycle, but will accept some *moderate* use of it, treat all charts with a grain of salt with solar.

BUT this assumes proper care!  Better than your vehicle in fact.  To do that with a standard lead-calcium like the Deka's, means using a charge current of 0.2 to 0.3C.  This gets you to float faster.  It may seem unreasonable to the weekend warrior with all week to recharge, but that is assuming you actually have a full week of good sun!  Be *slightly* agressive with agm's, even though it seems to go against conservative logic.

The whole gist here is that *quality* agm's in the vehicular category, while not truly ideal, have about twice the capability of a flooded thin-plate SLI battery, and if one does their homework for both application and power-budget, they can make what I would term a "casual / learner" battery.

Trying to keep one of these in good condition for as long as you can will pay off handsomely before you invest in a TRUE thick-plate deep cycle agm bank.   A mistake here won't send you to the poor house.

MStar1

Old Guy said:

MStar1 said:

The meter indicates FLOAT when it is >15V? It stays there indefinitely?
If so is there any charge current at all when it is in Float with >15V?
It should not be maintaining such a high Float voltage.
Float should be more like ~14.5V with these temperatures.
Can you check the daily max. battery voltage? See the meter map.

Yes! The meter says float green LED blinking and the voltage is always at 15.1 when I get there, and that checks out on my VOM. 
I will check the map this weekend.  This issue is about the only thing I'm not sure of now.  Hopefully the new settings will correct this.

During FLOAT the voltage should drop back down to the Float setting (with temperature compensation added). >14V in cold conditions but not 15.1V.
If the FLOAT setting is off for some reason then the Absorption might be off also. Have you been there during Absorption? If so what voltage is it reading then?
Did you know that you can review the historic internally logged data with the meter?
http://support.morningstarcorp.com/wp-content/uploads/2014/07/TSM2.IOM_.TSPWMLoadMap.03.EN_.pdf
I would suggest looking at the daily max. battery voltage and see if it ever gets above 15.1V since that would be even higher than what you see when you are out there at the site.

If there is no other charging source and the battery voltage doesn't get above where the Absorption voltage should be it seems like there might be a problem.
You can try turning on a load momentarily, watch the voltage drop and then return to FLOAT charging and see what voltage it is at then. 

I see several comments regarding Equalize. If you have the Auto-Equalize disabled with DIP SWITCH 7 OFF/ Down and never enable the manual Equalize it will never get activated. Other than that there is nothing unusual with Absorption voltages > 15V when it gets below freezing.

If you contact Morningstar tech support they will want to verify what the problem is. The more information you have and observations noted the better able they will be to either help you troubleshoot the issue or issue a warranty replacement if it is not working according to the specs. If the Float is out of spec it should be replaced.
"float mode and a tick over 15 volts" indicates a possible warranty replacement unless it is > 5 years old.
Checking the max. daily voltage on the meter might indicate a serious problem if the Absorption voltage is also off. 
If there is another small charging source you won't see an affect on the voltage regulation possibly for several days when the batteries need less and less current to bring the voltage up.