Let's make charging even more complicated:)

CALLD

Alright, so if absorb voltage, absorb time and temperature compensation wasn't arduous enough let's consider one more factor you should be applying if you really want to get the most out of your batteries:

Absorption voltage needs to be adjusted based on the depth of each cycle!

For VRLA batteries this is quite important.
Voltages are for 25°C
For 100% DOD absorb is set to 2.5v per cell
For 80% DOD absorb is set to 2.45v per cell
For 50% DOD absorb is set to 2.4v per cell
For 25% DOD absorb is set to 2.35v per cell
Float voltage is set to 2.3v per cell.

Cyclic life is significantly tied to the absorb voltage and DOD.

Time spent at absorb is also significantly tied to bulk charging current, with higher bulk current linked to longer time at absorb. Typically absorb is terminated when the charge acceptance drops below C/50, then a couple of hours at float tops them up fully.