A highly efficient fast charger for high capacity batteries and methods
for fast charging high capacity batteries. The fast charger preferably
comprises a rectified AC input of single or preferably three phases, with
an optional power factor corrected input, minimally filtered with high
frequency, high ripple current capacitors, which is switched with a power
switching circuit in the "buck" configuration into an inductor/capacitor
output filter. Metallized film capacitors are employed, to minimize the
rectified 360 Hertz AC component filtering while providing transient
switch protection and ripple current requirements for the buck regulator,
to provide a high current fast charger with substantially improved power
factor. High power, high frequency switching with minimized output filter
size provides a highly filtered DC output. The fast charger is adapted to
be constructed in a modular design for simple maintenance.