Woof -
Kinda threw this around while we were talking the other day, figured I'd put it out here for others as well.
For me it is pretty evident that there are numerous factors that affect the highest voltage a battery should see:
Type (FLA/SLA)
Design purpose (Cranking/Deep cycle)
Use case (Cyclic/Standby)
If cyclic, frequency of use, length of charging time between discharges
Depth of discharge (prevention of hard sulfation)
Temperature
Subtle differences in plate composition from manufacturer to manufacturer
Maybe more, I'm sure that's not it.
The biggest issues affected by the above are:
From excessive voltage:
Excessive water consumption for FLA
Cell dehydration for SLA (not reversible)
Positive plate oxidation (not reversible)
From low voltage:
Incomplete charging, resulting in less than 100% capacity available for use
Plate sulfation (not reversible)
Exacerbates cell balancing issues
So, there really is no "one size fits all" voltage to set a controller for. All of the above factors come into play.
I had a set of deep cycles, where a 13.8V float boiled them COMPLETELY dry in not a whole lot more than a years time. I drew a conclusion on how much water they would need based on an 8D that sat on float at the same voltage for 4 years and only needed water once - level never got NEAR the plates, nevermind dry the cells out.
It all depends. Check with the manufacturer, best bet.
Steve