Patent ID: 7800343
Filing Date: 2010-09-21
Classification: G01R

Abstract:
1. A battery life judging device comprising: a battery voltage detecting unit that detects a first battery voltage before charging of a battery begins and second battery voltages at a first time and at a second time subsequent to the first time, wherein both said first time and said second time are subsequent to a time when charging of the battery begins; a memory that stores the first battery voltage and the second battery voltage detected by the battery voltage detecting unit; a battery voltage gradient calculating unit that calculates a battery voltage gradient from the second battery voltages detected by the battery voltage detecting circuit at said first and second times; and a judging unit including first means for judging if the first battery voltage exceeds a predetermined voltage and second means for judging if the battery voltage gradient exceeds a first prescribed value, wherein the judging unit judges that a life of a battery has expired when the first battery voltage does not exceed the predetermined voltage and the battery voltage gradient exceeds a first prescribed value.