Restoration of battery capacity is usually not accomplished, but in the attempt, the battery owner learns how to keep the next set of batteries healthier.
Recharging lead acid batteries to full ASAP as often as possible is the Key.
The key to getting full asap is the proper amount of time at absorption voltage, and the proper time is a moving benchmark depending on depth of discharge, overall health of the battery, the lead/electrolyte ratio in the battery, the number of cycles since the last true full charge, battery temperature, and perhaps another dozen other variables.
How to know when 100% is reached? Hydrometer. and/Or an Ammeter
Do not listen to those who declare their batteries full because a charging source has dropped to float voltage. The battery's clock is ticking faster for these folks who put their faith in blinking green lights, especially if they discharge to 50%.
PD's manual is criminal, calling a 15 minute boost to 14.4v every 18 hours from 13.2 storage mode an 'Equalization' has no relation to a 15.5v+ true forced overcharge equalization that will max out the Specific gravity on all cells to their maximum potential.
Your 4 year old 12v battery fed by the WfCo likely cannot have much usable capacity restored even with a proper equalization. The PD will keep your next battery happier, but it can never do a true equalization at 15.5v+.
