Abstract: A method and apparatus utilizing a new parameter for assessing battery charge acceptance for controlling the charging process of the battery. The charge acceptance parameter comprises a terminal voltage profile which is determined during a variation in a diagnostic current. The slope of the terminal voltage profile is used in the charging process to assess the charge acceptance ability of the battery and thereby control the charging current. For a first group of batteries including lead-acid and nickel-cadmium batteries, the terminal voltage profile is characterized by an increasing profile slope as the charge acceptance ability of the battery is reached. For a second group of batteries comprising nickel-metal hydride batteries, the terminal voltage profile is characterized by a profile slope which approaches zero as the charge acceptance ability of the battery is reached.

Abstract: A battery pack and method for connecting battery modules to optimize current sharing and charging of the modules. The battery pack comprises a number of battery modules, each module having respective positive and negative terminals. Interconnecting cables are provided for connecting the respective positive terminals and the respective negative terminals. The interconnecting cables have equal electrical lengths so that the Ohmic resistance is the same for the cables. The battery modules are also arranged in close proximity to form an isothermal zone.

Abstract: A charger for charging a rechargeable battery. The charger comprising a circuit for producing a charging current having a variable level and a control circuit for controlling the charging current. During a first charging period the current is maintained at a level to rapidly charge the battery at a rate in amperes which is greater than the capacity of the battery in ampere-hours. The controller includes means for interrupting the charging current for a predetermined interruption interval. During the interruption interval, the charging current is maintained at a non-zero value. The controller also includes means for determining a resistance free voltage for the battery. During a subsequent charging period, the charging current is controlled in response to the value of the resistance free voltage.