Evgenij Barsoukov, Dan R Poole, David L Freeman: Circuit and method for determining battery impedance increase with aging. Charles R Hoffman, Cahill Von Hellens & Glazer, July 1, 2004: US20040128089-A1

An internal impedance of a battery (30) is automatically determined by operating a processor (13) to analyze current flowing through the battery to determine if a transient condition due to change of current is occurring and determining when the transient condition has ended. A voltage of the batter ...