Maximum charging voltage is specified slightly differently, when going from manufacturer to manufacturer. There are opposing needs, which influence this data. When wanting to have battery fully charged, and having done this quickly, maximum charging voltage of up to about 14.5V is 'allowed'. Typical specification of charging voltage in car battery charging application is: 13.3V...14.6V at 2000rev/min. BUT this rather high voltage includes some voltage drop of high current charging pulse accross internal resistance.

For longest life of battery maximum charging voltage should be less than 14.0V, while charging with rather small current.

Kai