Other

Matsushita Electric Industrial Co., Ltd.

Panasonic Ev Energy Co., Ltd.

Masayoshi Toyota

Tadao Kimura

Yusai Murakami

Norito Yamabe

A method and a charger for auxiliarily charging a secondary battery to a desired SOC with high accuracy. A charger for a secondary battery includes a charge termination condition storing unit which stores a relationship between open circuit voltages OCV of a plurality of secondary batteries and an amount of change of terminal voltage &#x394;V until a desired state of charge SOC is reached, which is previously created. A target terminal voltage Vmap at the time of the auxiliary charge is calculated by adding the amount of change of terminal voltage &#x394;V corresponding to the open circuit voltage OCV of a secondary battery to be auxiliarily charged to the open circuit voltage OCV which is measured. A terminal voltage Vb of the secondary battery at the time of auxiliary charge and the target terminal voltage Vmap are compared to each other by a comparison unit, and when the target terminal voltage Vmap is reached, auxiliary charge is terminated.

Charging control method for secondary battery and battery charger

A method of detecting and resolving a memory effect capable of detecting the memory effect with ease and with high precision and resolving even when the vehicle is in motion is provided. A current in a secondary battery is detected, a variation &Dgr;SOC in a residual battery capacity for a predetermined time period is calculated according to at least current integration by multiplying the detected current by a predetermined charge efficiency (S ), a temperature of the secondary battery is detected and a variation &Dgr;V in a no-load voltage for the predetermined time period is calculated based on the detected current, and an internal resistance corresponding to the detected temperature and the SOC is calculated (S ). A ratio k of the variation in the no-load voltage to the variation in the residual battery capacity is calculated (S ). If the ratio exceeds a predetermined threshold value kst, then the battery is judged to have a memory effect (S ), and the usage range of the SOC is extended for a predetermined time period (S ) or the correction of the SOC using voltages is prohibited for a predetermined time period(S ).

Method of detecting and resolving memory effect

A method for controlling a residual battery capacity of a secondary battery, by which the precision of the energy management of the system can be improved substantially, is provided. A current flowing through the battery is detected and the detected current is multiplied by a predetermined charge efficiency so that an operation on a residual battery capacity is performed at least by current integration (S ), an output voltage from the battery is detected and an average of the output voltages detected for a predetermined time period is calculated (S ), an average of the residual battery capacities obtained by the operation for a predetermined time period is calculated (S ), a reference voltage corresponding to the calculated average of residual battery capacities is referred to (S ), the reference voltage and the average voltage is compared (S ), and the predetermined charge efficiency is set variably based on a result of the comparison (S ).

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Toyohashi, Japan

Masayoshi Toyota