Method and apparatus for judging deterioration of battery

Abstract

A method and apparatus for judging deterioration of a battery are provided, thereby a correct judgement for the deterioration of the battery can be timely carried out so as to replace the battery with another if it is necessary. The apparatus for judging deterioration of a battery that supplies electric power to a load includes: storing means 23c for storing a minimum guaranteed voltage predetermined as a minimum value of a terminal voltage of the battery 13 when a given current flows into the load; voltage drop computing means 23a for computing a voltage drop due to an ohmic resistance and polarization resistance of the battery occurred in response to a discharge of the battery when a given current flows from the battery into the load; first comparing means 23a for comparing the minimum guaranteed voltage stored in the storing means 23c with a first difference value, which is obtained by subtracting the voltage drop computed by the voltage drop computing means 23a from an open circuit voltage that corresponds to a state of charge upon a start of the discharge of the battery; and first deterioration judging means 23a for judging that the battery is deteriorated if the first difference value becomes equal to or smaller than the minimum guaranteed voltage and the state of charge upon the start of the discharge exceeds a first specific value as a result of the comparison by the first comparing means 23a.

Description

technical field [0001] The present invention relates to a method and a device for judging the aging of a battery providing electrical energy to a load. Background technique [0002] Since an on-vehicle battery is widely used as a power source for starting an engine and operating an on-vehicle electronic device, it is important to accurately recognize the state of charge of the on-vehicle battery. [0003] However, in general, when a battery is repeatedly subjected to charging and discharging processes, the internal impedance of the battery increases, so that its dischargeable capacity gradually degrades from its fully charged state. [0004] Therefore, if one wishes to accurately identify a battery's state of charge, it is most important to know what capacity it can actually deliver. That is, it is necessary to accurately recognize the current capacity of the battery in a fully charged state. Hereinafter, the capacity in a fully charged state is referred to as a fully char...

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Problems solved by technology

Also, for activation polarization or concentration polarization, even when the state of charge is 40% or more, there may be a phenomenon that the resistance value changes so as to become larger than the initial value when the battery is not aged

[0014] Since changes in pure resistance, activation polarization, or concentration polarization in response to cell aging appear to be irregular, and there appears to be a cooperative relationship between the corresponding resistances, when only pure resistance, activation polarization, and concentration polarization are selected and monitored When one judges the aging state of the battery based on the observed, selected and monitored changes in the resistance value, an accurate judgment on the aging state of the battery cannot be obtained

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