aging AGM unusual behavior

I have a 150 amp-hr lifeline AGM that is sulphated and less than 80% capacity. It takes a long time to charge up. I've decided to keep using it until it fails.
I've noticed a couple of times that after the current has dropped fairly low (~0.6 amps), sometimes the current will rise during absorption,. What I have been doing when that happens is switching to float and sometimes equalizing. This time I've decided to just leave it at the absorption voltage 14.2V for a while. It's been there for about 18 hrs now, the battery is warm, but not hot (about 25C), and isn't making any noises. What's going on inside? Am I doing it good or destroying it?
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https://forum.solar-electric.com/discussion/351467/water-treatment-for-over-sulfation
Section 5.6 in the Concorde manual:
http://www.sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf
Low current (5% of battery 24 hour capacity rating), will get to something like 15.5 volts (or even as high as 18 volts for a 12 volt battery) during this process... You need a battery charger that can hold 5% rate of charge >15.5 volts.
Follow instructions.
So--You probably are not "killing your battery"--But you could increase charging voltage (while holding 5% max current) and monitoring temperature. As long as temperature and current specs are not exceeded--Go for it.
-Bill "not a battery expert/engineer at all" B.
CoachDad has been having some poor life from Concorde, and has been getting multiple versions of the manual--Which apparently are pushing for "more charging" as many of the failures are from under charging the Concorde AGM batteries (and possibly AGM batteries in general).
Marc Kurth, an engineer with lots of AGM/off grid system experience has been saying that most AGM failures (in his experience) are from under charging--Not over charging.
This post has Marc's and CoachDad's posts:
https://forum.solar-electric.com/discussion/comment/401425#Comment_401425
-Bill
-Bill
Below is a neighbors FLA battery going through a 3 hour Absorb and a 1 hour EQ. You can see at no time does the charge voltage drop below the set-point.
A shunt and a battery monitor are a waste of money on an AGM or FLA. Not worth the work either.
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To limit the charge current is a setting on a decent charger.
I think the Radian can do this from Outback but I can't remember.
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-Bill "just an observation by a non-expert" B.
Hopefully the info. on the battery is visable. That's the best photo I have.
2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.
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