KNowing the voltage that a charger brings a battery to, and how long it holds it there, is good.
Much much better is knowing how much Amperage the battery is accepting at said voltages the charger is seeking/holding.
One of these, displays not only voltage, but amperage and does the calculation for wattage.
It also displays watt hours, amp hours, minimum voltage, peak wattage(surge) peak amperage(surge).
Knowing the voltage only, is like saying I have to drive from A to B, not knowing where A and B is, but knowing your maximum allowed speed.
Seeing amperage flowing at that voltage, and how many amp hours/watt hours the battery accepted while the charger was on, is knowing the starting point, destination, the direction, route, speed of travel, and how long it ultimately took.
These wattmeters are accurate, down to about 0.3 amps, below that and they read a bit less than actual, how much varies but usually at about 0.1 amps of load they might read 0.0. They can be had for as little as 10$ if one shops around.
See what your charger is actually doing. Stop guessing, or assuming you know more about it than you do.
Charger marketing literature is often laughable, as they have to make it seem like they are better than their competitors, so they make up new terms, definitions, and imply defying physics is most likely within the realm of their super duper stage 8 owner fellate, charger.