Patent ID: 7075269
Filing Date: 2006-07-11
Classification: H02J

Abstract:
1. A charger for a secondary battery, comprising: a voltage increment means for incrementing a check voltage by a preset pitch of voltage, the incrementing being from a lowest check voltage lower than a rated equilibrium voltage at full charge of any secondary battery of all kinds to be charged; a charge voltage supply means for supplying special charging voltage, wherein the special charging voltage is higher than the rated equilibrium voltage at full charge of any secondary battery of all kinds to be charged, but does not enter an irreversible chemical reaction region; a switch means for switching voltage applied to the secondary battery between a voltage selected from the group consisting of the special charging voltages supplied by the charge voltage supply means, and the check voltage supplied by the voltage increment means; a current detection means for detecting an electric current flowing through the secondary battery during application of the check voltage to the secondary battery; a first judging means for judging whether the electric current detected by the current detection means is smaller than or as large as a preset standard electric current for judging; and a second judging means for judging whether a time required for a period from the last affirmative judgment judged by the first judging means to the present affirmative judgment judged by the first judging means is larger than r times as large as a time required for a period from the before-last affirmative judgment judged by the first judging means to the last affirmative judgment judged by the first judging means, where r is a real number not smaller than 1, wherein charging of the secondary battery is controlled according to the following: wherein in the first step the lowest check voltage is applied to the secondary battery for a short time, and the current detection means detects electric current flowing through the secondary battery during the short time; wherein in the second step the first judging means judges the detected electric current so as to execute a command selected from the group consisting of: wherein in the third step the switch means switches the applied voltage to the special charging voltage, the special charging voltage being applied to the secondary battery for a predetermined time, and then the switch means switches the applied voltage to the lowest check voltage, and a step returns to the first step; wherein in the fourth step the voltage increment means sets a renewed check voltage made by the present check voltage plus the pitch of voltage; wherein in the fifth step the switch means switches the applied voltage to the special charging voltage, the special charging voltage being applied to the secondary battery for a predetermined time, and then the switch means switches the applied voltage to the renewed check voltage, the renewed check voltage is applied to the secondary battery for a short time, wherein the current detection means detects electric current flowing through the secondary battery during the application of the renewed check voltage to the secondary battery; wherein in the sixth step the first judging means judges the detected electric current so as to execute a command selected from the group consisting of: wherein in the seventh step the second judging means judges the time required for the period from the last affirmative judgment judged by the first judging means to the present affirmative judgment judged by the first judging means so as to execute a command selected from the group consisting of: