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Open Roads Forum  >  Tech Issues

 > Another AGM conditioning question

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landyacht318

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Posted: 03/07/18 01:24am Link  |  Quote  |  Print  |  Notify Moderator

Do you have another healthy enough battery you can hook the questionable AGM to, in parallel?

The MEgawatt will self limit to its maximum amperage. My meanwell on a ~60AH calcium calcium maintenance free starting battery drained to 10v had to be turned down to its lowest setting to keep amperage below 20, as moreamperage than this the battery temperature rose quickly. My meanwell is capable of 40 amps.

A battery drained as low as the OP's I would likely not even bother with, unless I paralleled another 12v battery to it and then put then put the charging source on the other battery.

I'd still not have much hope. While most flooded deep cycle say 0% charged is 10.5v, I see 'some' AGM's saying voltages in the mid 11's equal 100% dischrged:

Crown1 AGM pdf saying 11.64 is 100% discharged

If the battery was slowly brough to 1.7v i doubt I would waste any time effort or electricity trying to get it to rest above 12v ever again. Even if it did, a small load would likely have it back below 10.5v again as its capacity is likely long gone.

but best of luck and keep flammables away from it

Smitty77

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Posted: 03/07/18 08:33am Link  |  Quote  |  Print  |  Notify Moderator

Naio - My apology in advance, if you feel this rude to tag along on this thread. Assure no attempt of highjacking. But the 'Another AGM conditioning question' heading - and what you are doing, are very similar to what I'm doing with a bank of Lifeline's. So, I thought it fit into the general conversation.

Many of the posters on this thread have been helping with a bank of X's 4 Lifeline L16's AGM, that at age 5 appear to be on their way South for ever[emoticon]!

I've now completed two sets of Magnum 4 hour Equalizing/Conditioning runs. (Two back to back, to get to the 8 hours Lifeline Tech Manual indicates.) I did one set. Then the next day drew the bank down to 95% SOC, and fully charged them. Then the third day, one again I saw Full Charge on the Magnum, and read a full bank of 12.7V at the battery with Multi Meter. Ran another two sets of Magnum Equalizing/Conditioning. (Temperature compensated to between 15.4 - 15.6V.).

After reading MW's input of a 14.4V steady feed and wait until battery drops to 1.0. I've reset the Magnum Equalize value to 14.4V to ensure this stead feed of 14.4V.

Battery bank indicated they're full when I started this. 20 mins into it, 27A are indicated.

So question here, with a full charged bank of 800AH Lifeline's, and starting this feed of 14.4V - is the 27A an indication of anything? If fully charged, should it be closer to the 1.0 level? Or is this an indication of a bad battery of batteries or cells within batteries? Temp started at 67F and 15 mins later dropped to 64F? (By chance, even though the Magnum indicated Full when I looked, it may have just finished a Float Cycle, which had the temp up to 67F when I started?).

OK - Again apologize if this is considered a hijack... But thought it was relevant to AGM conditioning[emoticon]! Will start a new thread if I'm intruding...
Smitty

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Posted: 03/07/18 09:08am Link  |  Quote  |  Print  |  Notify Moderator

Naio wrote:

Ok. Is the solar trickle charge an ok option, too?
Solar is always good.


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Sam Spade

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Posted: 03/07/18 09:19am Link  |  Quote  |  Print  |  Notify Moderator

landyacht318 wrote:

Do you have another healthy enough battery you can hook the questionable AGM to, in parallel?


YIKES. [emoticon]

NOT good advice.

The "healthy" battery can provide hundreds of amps in a short time......and is exactly the OPPOSITE of what he is trying to do, which is limit the charging current.

It looks to me like he has charging equipment that is WAY out of his league. An inexpensive 6 to 10 amp charger should be OK, if left connected for a couple of days. And then leave it DIS-connected for 24 hours. Then check the voltage. Even if it is above 12.6 at that point, it's useful life will probably be VERY short.


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Naio

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Posted: 03/07/18 10:25am Link  |  Quote  |  Print  |  Notify Moderator

Thank you, landy. I was wondering about effort vs. chances of success.

I do have my big fiamms, but too heavy for me to move and I think they are farther than my jumper cables' length [emoticon].

Smitty7, feel free! Did you read the whole thread? Lots of good info.


3/4 timing in a DIY van conversion. Backroads, mountains, boondocking, sometimes big cities for a change of pace.


Smitty77

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Posted: 03/07/18 12:12pm Link  |  Quote  |  Print  |  Notify Moderator

Naio - Thanks! And yes, I read this full thread on my quest to both understand how I messed up my bank and now how to recover as much as possible[emoticon]!

It's coming up on 4 hour now, down from 15A and up to 73F (But of course, day is now a bit warmer too[emoticon]!.

Will go another 4 hours, see what the Amp is showing... If not working it's way down, I'll probably just go ahead and stop after that 8 hours of 14.4V - unless advised otherwise here[emoticon]!

Smitty

landyacht318

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Posted: 03/07/18 12:39pm Link  |  Quote  |  Print  |  Notify Moderator

Smitty, I am not understanding your previous efforts then. An Equalization, or conditioning procedure should only be performed on a battery that is otherwise fully charged.

Meaning it was held at a regular absorption voltage until amps tapered to a low level.

Your reports of amps tapering now at 14.4v would seem to indicate you performed the previous 15.5v conditioning on batteries that were no where near fully charged when you started, and amperage required to push 4 undercharged lifelines to 15.5v would have been excessive.

I did not see anything where you said you discharged themn again then are performing the regular 14.4v absorption on them

Each time you discharge your lifelines they should ideally be brought upto 14.4v until amps taper to 0.5% of the total capacity of the bank. The charger does not taper the amps, it seeks to bring the batteries to, then hold them at a voltage, and as the battery fills it, requires less and less amperage to maintain that voltage.

So if the batteries are till accepting 15 amps at 14.4v they are not close to being fully charged. not until amps taper to 4, for your 4 L-16's, at 14.4v at 77f battery temperature.

The tapering to 0.5% at Vabs, can take a huge amount of time on batteries that have not been fully charged in a long time.

I've seen my northstar AGM take 3 hours for amps to taper to 0.5% of capacity, and after 2 weeks of partial state of charge cycling, it then required 12 hours held at absorption before amps tapered to 0.5% of capacity.

So basically the longer the tapering takes to reach the treshold, the worse the battery has been treated, meaning it was not being fully charged before the next discharge began.

And this partial state of charge cycling is very hard on a lead acid battery, but seemingly especially so on AGM's

Fully charging is actually pretty easy, Simply have the charging source seek and hold absorption voltage until amps taper to a certain level. The hardest part is having a charging source which can actually do this without trying to follow the bean counter's and lawyer approved comproimised one size fits all algorithm.

Seek and Hold 14.4v until amps taper to 0.5% of total battery capacity.

Only then should one initiate the 'conditioning' procedure, if required. If the batteries were regularly brought to absorption and held there until the amps tapered to the required level, the conditioning procedure would likely never be required.

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Posted: 03/07/18 01:12pm Link  |  Quote  |  Print  |  Notify Moderator

"Then the third day, one again I saw Full Charge on the Magnum, and read a full bank of 12.7V at the battery with Multi Meter."

Does not compute. When the Magnum at say 14.4 gets the batts full, they should be at 14.3999999v

Then if you disconnect the batts from all loads and charging, they should be at 13.x right away, and then not get down to 12.7 for a couple of days. Except AGMs which will rest at more like 13 instead of 12.7


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Posted: 03/07/18 01:28pm Link  |  Quote  |  Print  |  Notify Moderator

As long as every single cell avoids overheating apply 14.4 volts even if it takes four days at 24 hours per day charge time. Naio's predicament is she feels sensitive about over-amping the Megawatt which is a valid concern. It is a tough power supply but reasonable is reasonable. It is designed to augment a properly sized converter, not replace it.

AGM batteries have a formidable charge acceptance. With the 2-story Lifeline 31 I have whacked it with 137 amperes to achieve 14.4 absorbsion 14.4 volts limit.

My error with Naio is I somehow believed she was dealing with wheelchair batteries. So right off the bat I was standing on non-existent ice.

By virtue of physics and chemistry only a cell short or multiples thereof can cause an AGM battery to overheat if voltage limited charging is employed. So checking the battery by hand (an infra red scanner is easier and best) will reveal excess heat either in a single cell or series cells.

WEAR EYE PROTECTION! Please! I mean it!

Once a rig's converter set at 14.4 volts has amperage slump to LESS than the power supply's max amperage limit, then the power supply can constant voltage charge the battery for hours and even days if required.
=============================================================================================================================================================


Let's use some common sense in diagnostics...

A 135 amp hour AGM as an example.

Connect a charger to it -- converter or power supply it does not matter

Over whatever amount of time it takes, by keeping track, and voltage limiting to 14.4 it seems as though the 135 amp hour battery has taken 290 amp hours worth have charging and has not had its amperage decline to one half percent of total amp hour capacity (in this case less than 6.75 amps)...

The battery is bad

If amperage ALMOST declined to 6.75 amps than try the battery under load and if it works to your satisfaction then it works. If it falls flat on it's face it fails meaning a bad battery.

Think of a five gallon bucket. If you jam 6 gallons into it, is it a five gallon bucket? No. It has a leak. A battery operates on chemistry so the leak can be twiddled with -- to a point. By equalization or conditioning charging.

If it fails to respond to equalization or conditioning twiddling then you have a bad battery.

If you want to be snotty about the protocol

All batteries have a charge efficiency factor measured in percentage of overcharge needed to bring a discharged battery to full charge from being discharged.

A neglected battery has a moderate fault in amp hours needed to return to full charge

A bad battery can never be returned to full charge. Endless charging, never reaching one-half percent of amp hours at 14.4 volts, or reaching the magic figure but then rendering a notable lack of ampere hours of charge storage.

The lack of charge storage can be treated with conditioning. The never reaching the one-half-percent even with ridiculous amounts of excess amperage at 14.4 volts is like allowing an at bat hitter slack. But "Strike twenty-seven you're out" should be ample proof the battery is scrap.

Hope this helps...

Smitty77

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Posted: 03/07/18 01:49pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13, LY, MW - Thanks again~!

And BFL13. Pretty good assumption you understand, it's me that does not do a 'Duh!' how can this be 12.7V 30 mins after be 12.7V? You know 'It's not you, it's me...'.

Watching temps via ARC-50 Magnum Temp Sensor, which is very close to the battery Infrared Temp readings. I did the posts, I'll do some scanning where I believe the Cell's should be, to see if temps vary on a specific battery cell.

If the battery temps look good, I'll continue the 14.4V... Now 1.5 hours into the second cycle of 4 hours. Still holding 15A[emoticon]!

Side question. I validated that the 9" Interconnects are #3 welding wire. That passes my filters, but I've proven I've been wrong before. His that an appropriate gauge of wire for 6V 400A connections?

Best,
Smitty

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