Patent ID: 7212006
Filing Date: 2007-05-01
Classification: B60L,G01R,Y02T

Abstract:
1. A method of evaluating the condition of a battery, comprising the steps of: (i) selecting a known external load the resistance of which is based on the type of the battery, such that when the load is connected across the battery a large current is drawn; (ii) selecting a nominal value for the internal resistance of the battery based on its type; (iii) connecting the external load across the terminals of the battery for at least one short duration interval(s), measuring the voltages; across the battery and across the external load while current is conducted through the load, and, if more than one such measurement is made of each voltage, taking the average of the measured values of the voltages ; (iv) dividing the measured value of the voltage across the load, or, if more than one measurement is made, the average of the measured values of the voltage across the load by the resistance of the external load to determine the current drawn from the battery; (v) dividing the measured value of the voltage across the battery, or, if more than one measurement is made, the average of the measured values of the voltage across the battery by the determined value of the current in order to calculate the internal resistance of the battery; (vi) comparing the calculated internal resistance of the battery with the selected nominal value of the internal resistance of the battery so as to determine whether the calculated value is equal to or larger than the selected nominal value or not; and (vii) provide an output to a user responsive to the determination in step (vi).