AGS settings for Outback FM60

Cariboocoot · January 2013

Re: AGS settings for Outback FM60

The "bottom end" of a 24 Volt system is 21 Volts. 23 to 24 is still going to be okay. You've drained them deeply, but as Bill said not "dead". I have my low Voltage disconnect set at 24 for this reason: 24 Volts under load is most assuredly above 50% SOC.

Float is typically 1 Volt less than Absorb on a 24 Volt system (if you've no other guidelines to go by).

BajaSun · January 2013

Re: AGS settings for Outback FM60

Great.
One battery string disconnected so I can test its' voltages later. Sure was nice to see absorbtion on the one bank even though its solid cloud! More panels for the two strings, right?

Same plan? Use single bank for a while with max. absorb times, see how its capacity holds up and maybe in a week EQ it?

Then once its in good shape, work on the other and if the two strings are close in voltage (within 0.?V) parallel them back together?

Cariboocoot · January 2013

Re: AGS settings for Outback FM60

Basic formula for getting the right amount of panels for a battery bank: 10% of the Amp hour capacity for peak potential charge current. In other words, for every 100 Amp hours (at whatever Voltage) of battery you try for 10 Amps of current (at the system nominal Voltage). This isn't an absolute and it is not necessary to see that Voltage every charge period, it's simply a short cut to having enough panel. Coupled with 25% DOD and the right Absorb time length (as you've learned the hard way) you get a balanced system that will work right about 90% of the time. Caveat: there are always exceptions.

By charging half your battery bank at a time you can put a greater percentile of current to it, bringing it up faster which allows for more time spent in Absorb. Just don't leave those other batteries off charge for too long or they will get worse.

What you're looking for is a resting Voltage that is both high enough and lasts long enough (like overnight) to indicate the battery is actually fully charged.

BajaSun · January 2013

Re: AGS settings for Outback FM60

Checking rest voltage on the disconnected bank of batteries after 3 hrs, this is what they say: 6.27, 6.25, 6.31, 6.29 with the specs saying 6.40 as fully charged that's 97-98% charged. Doesn't seem too bad?

Blackcherry04 · January 2013

Re: AGS settings for Outback FM60

BajaSun wrote: »

Checking rest voltage on the disconnected bank of batteries after 3 hrs, this is what they say: 6.27, 6.25, 6.31, 6.29 with the specs saying 6.40 as fully charged that's 97-98% charged. Doesn't seem too bad?

Remember the " Exposed " comment you questioned ?? ( Exposed to the Electrolyte ) , voltage means nothing without capacity. It just depends how much of the plate is causing that voltage. You can get 6 V out of 4 flashlight batteries. You have lost capacity because a portion of the plates have sulfated and are inactive, that is what your trying to remove with the longer charge and EQ.

BB. · January 2013

Re: AGS settings for Outback FM60

From an earlier post I made here:

A 48 Volt Bank at resting voltage at 77F is around 45% state of charge (see generic bank voltage chart from Battery FAQ--12.00 volts).

However, the actual resting voltage is really dependent on the initial specific gravity of the electrolyte fill...

So, what was your "full charge" Specific Gravity?

One thread here
Another thread here

So, to pull from earlier posts:

Well mixed electrolyte is important--so if you notice all cells not coming back to "full charge" level of s.g., then there is a good chance that "mixing" (equalization) will bring the s.g. back up to your logged readings (keep these as your "good batteries" / "fully equalized" numbers.

The amount of variation you are seeing is not that great (less than 0.030 between all cells). And having "high" s.g. is not always a good thing either.

I ran across this page on why different types of batteries have different starting s.g. fills... Is pretty interesting:

Specific Gravity vs Applications
1.285 Heavily cycled batteries such as for forklifts (traction).
1.260 Automotive (SLI)
1.250 UPS – Standby with high momentary discharge current requirement.
1.215 Geral applications such as power utility and telephone.

As mentioned earlier, the specific gravity (spgr.) of a fully charged industrial battery, or traction battery, is generally 1.285, depending on the manufacturer and type. Some manufacturers use specific gravities as high as 1.320 in an attempt to gain additional Ah capacity, but at the cost of a shorter cycle life.

...

Higher Gravity = vs Lower Gravity =
More capacity / Less capacity
Shorter life / Longer life
Higher momentary discharge rates / Lower momentary discharge rates
Less adaptable to "floating: operation / More adaptable to "floating" operation
More standing loss / Less standing loss

Also on that page is the formula between cell resting voltage and specific gravity:

Specific gravity = single-cell open-circuit voltage - 0.845 (example: 2.13v – 0.845 = 1.285)
Or
Single-cell open circuit voltage = specific gravity + 0.845.

So, if you are getting 46 volts after resting, if the formula is correct (and your battery is around 77F) your specific gravity should be:
46v/24cells - 0.845 = 1.072 (dead?)

47v/24cells - 0.845 = 1.113 (~20% state of charge)

Yuasa states that the temperature correction for SG is:
specific gravity changes by +.001 for every -3 degrees Fahrenheit.

J.R. Buchanan did a nice set of charts on battery SG and temperature based on a 100% charge = 1.265 SG.

By the way, do you have a Battery Monitor?

-Bill

If you look at the (simplified) equation for voltage vs specific gravity--The difference in state of charge is a simple difference in voltage or specific gravity (offset by a constant).

So, in your case the high-low voltage gives you a difference of 0.060 volts or a difference of 0.060 sg units.

From what I have read, a couple battery vendors (flooded cell) recommend equalization if the SG is different from low to high cell by more than 0.015 to 0.030 SG units (sg is a ratio--so it is really unit-less).

To be honest, I have never looked at SG of a sealed battery in quite that way before--But, it would appear that if you can do a slow charge (around 2.5% to 5% maximum?) rate of charge at a "slightly" elevated Absorb voltage (or at least hold absorb voltage for hours)--And see if you can bring the cells up to a stable "full charge" (full charge for a flooded cell is 2.5 to 5% current flow and SG not changing between readings taken 30-60 minutes apart)...

It probably would be best to charge cells "singly" at 2.4 volt each--But not many people have 2.4 volt (relatively) high current chargers floating around (i.e., around 1-5 amp charger per 100 AH cell).

Remember you are over charging the series cells that are already at 100% SOC so you can "leak" current to recharge any weak cells back to 100% too. So you don't want too much current through the "good cells" to cause them to overheat and vent--thereby creating a whole battery bank of bad cells.

Anyway--more of a point of discussion here--Not claiming this is the "answer".

-Bill

BajaSun · January 2013

Re: AGS settings for Outback FM60

OK. Lifeline has a suggested capacity test - basically discharging with a 25A load and timing it, then checking the numbers. I am not able to do that down here, or know of a company that can so that is another reason I'm relying on all you gurus for the great advice. How long can I leave the disconnected bank without charging?

I'm thinking I'll need at least ten days to work on the connected bank before moving to the other one - is that acceptable?

westbranch · January 2013

Re: AGS settings for Outback FM60

Quick fix is to disconnect bank 2, charge bank 1 all the way to float, then reverse and charge second bank2, so that you get both as 'full' ( a relative term right now)as possible. Then proceed with your corrective charging program.
I think that iis the best you could do in this circumstance.

Note that you should do a daily V check on both banks to be sure bank 1 is improving and that bank2 is stable. If B2 starts to drop, give it a boost or full charge if possible.

Cariboocoot · January 2013

Re: AGS settings for Outback FM60

Maybe I'm getting confused (wait 'til you're old, children

) but I thought we were talking AGM's here. If so, exposed plates is probably not an issue (although sulphation still can be).

How long you can leave batteries without charging depends a lot on how charged they are to begin with. More than 75% is pretty safe. Fortunately AGM's have a very low self-discharge rate.

Blackcherry04 · January 2013

Re: AGS settings for Outback FM60

BajaSun wrote: »

OK. Lifeline has a suggested capacity test - basically discharging with a 25A load and timing it, then checking the numbers. I am not able to do that down here, or know of a company that can so that is another reason I'm relying on all you gurus for the great advice. How long can I leave the disconnected bank without charging?

I'm thinking I'll need at least ten days to work on the connected bank before moving to the other one - is that acceptable?

10 days should be a reasonable amount of time to see if your making any headway. If it was me I'd have my generator on at 6:00 in the morning and would have a Bulk charge done before the sun came up, the rest of the day solar would be doing the absorb all day long. You can take Route 66 or the Interstate.

Again, I use my overnight Load as the test, If all of a sudden I am @ 24.2 instead of 24.4 in the morning and the Amp's consumed are the same and charging and Loads were the same, I'v lost capacity.

On the batteries you have pulled, just check the voltage on them every couple days.

Blackcherry04 · January 2013

Re: AGS settings for Outback FM60

Cariboocoot wrote: »

Maybe I'm getting confused (wait 'til you're old, children ) but I thought we were talking AGM's here. If so, exposed plates is probably not an issue (although sulphation still can be).

How long you can leave batteries without charging depends a lot on how charged they are to begin with. More than 75% is pretty safe. Fortunately AGM's have a very low self-discharge rate.

Exposed to the Electrolyte !!!! If a Plate is Sulfated, it is NOT exposed to the electrolyte, The Coating Sulfate is Blocking it.

BajaSun · January 2013

Re: AGS settings for Outback FM60

Sounds good.

Thanx again everybody.

If you're interested, I'll let you know how things work out?

Cariboocoot · January 2013

Re: AGS settings for Outback FM60

Blackcherry04 wrote: »

Exposed to the Electrolyte !!!! If a Plate is Sulfated, it is NOT exposed to the electrolyte, The Coating Sulfate is Blocking it.

Yeah, I knew I was probably getting confused.

It's been a rough year!
Uh-oh ... this is only the first day!

BB. · January 2013

Re: AGS settings for Outback FM60

Sure--Finding out how things work out is important for everyone that follows. We like to know that we are giving good advice--Or how to give better in the future.

And--You can make your own 25 amp load pretty easily... Use your inverter plus a heater or standard (if you can find them) high wattage filament light bulbs:

25 amps * 24 volts * 0.85 typical inverter efficiency = ~510 watt AC load

Get an inexpensive electric heater run on load (may be around 500 watts) plus a 100 watt light bulb--And there you go.

Concord says their batteries should supply 80% of rated capacity--less than that is a "failed battery".

Practically speaking--Say you plan on running your system to a maximum of 50% discharge (25% discharge for two day without sun)... If the batteries still have charge at the end of your test to 50% discharge--then the bank is "still good for your use". If the battery bank collapses--It no longer meets your needs.

Note--It is very possible you have a mix of "good" and "bad" batteries--Doing the testing will allow you to find the failed battery(ies)--You can replace them, run a reduced bank, or even try some charge/discharge cycles and see if you can "recover" the failed battery

-Bill

BajaSun · January 2013

Re: AGS settings for Outback FM60

OK.
So as I'm slowly "reconditioning" each bank, monitoring capacity (whicg I think maybe getting better already as it was at 24.6 this morning and has been lower of late) - I'll be looking for a battery (or more) that simply refuse to come up to par?

As for the capacity testing - I have to do rgw whole bank though as I need 24V for my inverter. I would have thought that individual batteries should be tested for proving?

BB. · January 2013

Re: AGS settings for Outback FM60

Testing the whole bank and monitoring the voltage on each battery (with a meter) would probably be "good enough"... The first battery that drops below ~12 or 11.5 volts is your weakest.

You can test each battery--But then you would need to recharge each one separately (you don't want to mix charged/discharged batteries in the same series string).

Depends on your needs (your only place to do work, or do you have a shop/2nd home else where with grid power where you can take time/energy to test each battery)... You could do the single battery testing at your off grid location if you have parallel battery strings (take out one string and test the batteries separately). Just depends on what works best for you.

-Bill

Vic · January 2013

Re: AGS settings for Outback FM60

The only cautionary note that I'd add, is to monitor the bank voltage very carefully during this type of discharge testing. AND, monitor the voltage of every battery often, as BB Bill was indicating. Even weak batteries might be recoverable if they are not run down too far.

Vic

BB. · January 2013

Re: AGS settings for Outback FM60

Yea--You don't want to kill a battery just because of testing for bad batteries.

-Bill "self fulfilling prophecy" B.

BajaSun · January 2013

Re: AGS settings for Outback FM60

I don't feel comfortable discharging batteries at this moment as that is what I'm trying to amend! I charged this string up to 28.6V this morning with the generator (2 hrs) and it's been held at that with my CC's all day so this gives me confidence that I can hold a string at a higher voltage to de-sulfate them (eventually). So, same plan mañana as well as a first dose of 31V EQ for an hour, probably mid day after they've been held with the sun at 28.6V

westbranch · January 2013

Re: AGS settings for Outback FM60

not so fast pilgrim... lets see what voltage we get down to in the morning after a nights use...

BB. · January 2013

Re: AGS settings for Outback FM60

And cycle them as normal at night (probably at least 25% to ~75% state of charge, at least)--Discharging/Charging is going to be helpful in recovering capacity (if needed/possible).

-Bill

inetdog · January 2013

Re: AGS settings for Outback FM60

BajaSun wrote: »

... so this gives me confidence that I can hold a string at a higher voltage to de-sulfate them (eventually).

There are two forms of the lead sulphate on the plates. The first is the "soft" or spongy form, which is initially created during periods of low SOC. It can be forced back into solution as Lead and sulphuric acid by proper charging. The second is "hard" or crystalized lead sulphate, to which the initial deposits eventually change if left undisturbed. These *cannot* be reclaimed by simple application of a charging or even equalizing voltage because the energy required to break them up is higher than the point at which all of the current is going to electrolyze water instead.
By all means be patient, but be aware that really badly abused batteries cannot recover completely through charging.

BajaSun · January 2013

Re: AGS settings for Outback FM60

OK bosses! Will do, hold em at 28.6V all day for a few days more and check things out. Sorry - getting ahead a little....

westbranch · January 2013

Re: AGS settings for Outback FM60

Ah yes, the young Jedi learns patience...

BajaSun · January 2013

Re: AGS settings for Outback FM60

One thing I don't think I asked/clarified:

Old school (flooded lead acid batteries) told you they were bad when their voltage was low (24.6V) and would almost immediately increase to Absorb ~ 28+V when connected to an external charger ie a generator. Correct? Even though the newer AGM's are touted as faster recharge - are they meant to act this way too, or is it a similar situation?

Maybe this is a stupid question - I'm just trying to get my head around all this info that's been posted - young Jedis' brain sponge can get sulfated too!!

Blackcherry04 · January 2013

Re: AGS settings for Outback FM60

BajaSun wrote: »

One thing I don't think I asked/clarified:

Old school (flooded lead acid batteries) told you they were bad when their voltage was low (24.6V) and would almost immediately increase to Absorb ~ 28+V when connected to an external charger ie a generator. Correct? Even though the newer AGM's are touted as faster recharge - are they meant to act this way too, or is it a similar situation?

Maybe this is a stupid question - I'm just trying to get my head around all this info that's been posted - young Jedis' brain sponge can get sulfated too!!

Are you talking about one Battery ?? With one battery, depending on the chargers output, yeah the voltage could increase pretty fast. With a 1000 amp hr bank it would much slower. Most chargers would have a certain low voltage at max output current. Like a 12 v, 60 amp charger's would have a minimum 12.6 volt or so voltage output until the voltage in the Battery / Battery Bank rises.

Cariboocoot · January 2013

Re: AGS settings for Outback FM60

BajaSun wrote: »

One thing I don't think I asked/clarified:

Old school (flooded lead acid batteries) told you they were bad when their voltage was low (24.6V) and would almost immediately increase to Absorb ~ 28+V when connected to an external charger ie a generator. Correct? Even though the newer AGM's are touted as faster recharge - are they meant to act this way too, or is it a similar situation?

Maybe this is a stupid question - I'm just trying to get my head around all this info that's been posted - young Jedis' brain sponge can get sulfated too!!

Not sure I understand this question.
FLA's and AGM's behave much the same for charging. How fast they come up to Absorb depends on how deeply they are discharged, the capacity of the battery, and how much current is put to them.
It is even possible to charge them too fast.
Some charge controllers (such as Outback) have a minimum Absorb time setting as well, because under certain conditions the Bulk stage can be too short to "run up enough time on the Absorb clock". Thus you could have "at least 1 hour Absorb" and "at most 4 hours Absorb" and "End Amps".

People tend to miss the point of how important the length of the Absorb stage is.

BajaSun · January 2013

Re: AGS settings for Outback FM60

I am presently working on one string of 6V 400AH Lifeline AGM's configured to 24V.

The morning low battery light is on and reads 24.6V

My generator is wired through the FX charger which if I rmember correctly limits current to 20A?

Anyway, on firing up the genny, I watched the voltage readout go up fairly fast (a few minutes) from 24.6 to absorb voltage of 28.6V

Maybe I should have mentioned this a while back - I thought it was one of the advantages of AGM's as they charge faster - but it really seems like they are acting just like flooded lead acids - gone bad.

This would also happen when I had the two strings wired up, albeit a little slower.

Blackcherry04 · January 2013

Re: AGS settings for Outback FM60

BajaSun wrote: »

I am presently working on one string of 6V 400AH Lifeline AGM's configured to 24V.

The morning low battery light is on and reads 24.6V

My generator is wired through the FX charger which if I rmember correctly limits current to 20A?

Anyway, on firing up the genny, I watched the voltage readout go up fairly fast (a few minutes) from 24.6 to absorb voltage of 28.6V

Maybe I should have mentioned this a while back - I thought it was one of the advantages of AGM's as they charge faster - but it really seems like they are acting just like flooded lead acids - gone bad.

This would also happen when I had the two strings wired up, albeit a little slower.

Thats pretty fast, but not knowing you system and the amount of capacity you have lost, possible. Was your solar producing ?? how many amps. The FX 3524 has a 85 amp charger, so it might be higher with AGM's, if you don't have it limited to 20 amps as you said.

Where were you reading this voltage ?? at the battery bank ? it's not odd for there to be a volt difference between the battery voltage and a meter .

BB. · January 2013

Re: AGS settings for Outback FM60

AGM can charge faster because they can accept more current than flooded cell during bulk stage, without over heating (when the battery can accept more current than the charge controller can output--charge controller is current limited).

Once the batteries are over ~80-90% state of charge, both will hit the absorb voltage, and the current will slowly tapper down to near 1-2% final charging current.

Of course, if the AGM has begun to sulfate, and the battery bank voltage begins to rise "too quickly"--Then its ability to accept high current will be compromised (and it storage capacity too).

-Bill

AGS settings for Outback FM60

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