Yes, I agree with Maine 100% on this.
And, the batteries I was trying to revive experimentally are a perfect example of what he said. They lived their 8 years as a power source for my radios
in my home. They were on an Iota DLS-45/IQ4 smart charger with a float voltage of 13.6VDC 24/7. They obviously didn't move around much, but were stationary at my radio
Occasionally, they'd get a healthy draw of 90A with my 12V 500 watt HF amplifier on, but the charger was on at the same time so they really didn't get much of a workout unless we lost power....a relatively rare occurrence.
Sometimes, not often, I'd "exercise" them by pulling the plug on the battery charger
for a day or two, and using the radios
entirely from the batteries.
During equalization, the batteries bubbled vigorously and got warm, but not hot. You could feel the warmth on their sides, but not really at their terminals. There was no noticeable loss of electrolyte. These batteries, like all of my T-105s, have WaterMiser caps.
Conclusion: Despite being on a 13.6VDC float charge 95% of the time, they nevertheless aged and lost capacity (most likely through stratification and sulfation) over those years. I removed them from service about six months ago when they were down to about 45% capacity (as measured by a Midtronics tester) and were losing it fast.
A couple of weeks ago when I tried to revive them, they were at about 30-35% of original capacity. After several days of jolting them pretty good with a healthy equalization charge of 16.5VDC @ about 20 amps, they still tested about 35% capacity, so no improvement there.
There was a sort of "improvement" though: the cell bubbling was more uniform (one cell barely bubbled at all when I began the treatment) and the pair now holds a charge much better than before, i.e., the self-discharge rate is much less. However, their capacity didn't really improve.
I did do a real (direct) capacity test with them, however, putting a 12 amp load on them. They delivered just over 70AH in a 6-hour period before falling to 10.0VDC under load, which is consistent with my earlier estimate of 30-35% capacity. A new T-105 pair, broken in, would have gone almost 20 hours before dropping that low.