In the old days when car batteries would fail and not charge there was a solution which fixed about 80% of them. The problem was the scale and debree from the platelets would be gathered at the bottom of the battery touching the plates. You could never get them to charge or they would discharge as quick as they were charged.
By emptying the battery and flushing it, putting in new electrolyte the batteries would then again last many more years.
To a small degree, back then we came to the belief that often expensive batteries had more clearance at the bottom while cheap batteries often had less clearance.