A battery charger controller is coupled DC output terminals of an AC-DC (or DC-DC)
adapter containing an AC-DC (or DC-DC) converter. A controlled current flow path
between input and output terminals of the battery charger controller circuit is
controlled to provide a substantially constant current to charge the battery to
a nominal battery voltage. When a constant voltage output of the said adapter transitions
to a value that limits available charging current to a value less than programmed
constant charging current, current flow drive for the controlled current flow path
is increased for a limited time interval. Thereafter, the controlled current flow
path gradually reduces charging current as the battery voltage remains at its nominal
battery voltage until the charge is complete or otherwise terminated.