Mex, the Vector is out of business and the ones made by Black and Decker are hard to find anymore too.
They and other chargers normally shut down when they get the battery to about 97% ("Automatic" charger) How long that takes depends of course on the size of the battery in AH and the charging amps size of the charger.
To get from 97% to 100% you need a different sort of charger that stays on past that 97% like a converter does (except note that they mostly drop to a Float voltage before reaching 100%, and get to the 100 sometime later while on Float.
If you want to remain at Vabs till you get to 100% and then drop to Float, you need an adjustable voltage power supply type of charger.