Yazaki Corporation

Hideaki Kamohara

Youichi Arai

Tsutomu Saigo

Tomohiro Kawaguchi

Michito Enomoto

Hiroshi Iizuka

Takitaro Yamaguchi

Tatsuo Fujinami

Masatoshi Kishida

Norihito Enomoto

Mamoru Katsumata

A method and apparatus are provided, by which a state of charge of a battery is accurately computed without being influenced by the polarization effect. An estimated voltage of the battery in a constant load discharge with a predetermined large current value is estimated from a voltage-current characteristic when the discharge current of the constant load discharging process by the battery that is in an equilibrium state is decreasing from the predetermined large current value corresponding to a maximum supplying electric power to the load. A difference between the estimated voltage and an open circuit voltage, which estimates the estimated voltage and is a terminal voltage of the battery that is in an equilibrium state before the start of the constant load discharge by using the predetermined large current value, is calculated. Then, the difference is memorized by first memory means for memorizing a residual voltage drop defining as the residual voltage drop due to a residual polarization at the end of the discharging process of the battery . The residual voltage drop memorized by the first memory means is added to the estimated voltage of the battery , thereby a present charging capacity of the battery is computed.

Battery capacity calculating method and device therefor

A method and an apparatus for computing a charging state of a battery without being affected by an influence of polarization are provided. First computing means computes a voltage-current characteristic including the influence of the polarization during an decrease of a discharge current of the battery on the basis of a terminal voltage and discharge current measured while the battery carries out a constant load discharge with a current value large enough to cancel a charge-side polarization arisen in the battery at least just before the discharge. A second computing means shifts the voltage-current characteristic to a specific extent in the direction of a voltage coordinate axis. A residual voltage drop value in advance stored by storing means is added to a present estimated voltage value estimated by estimating means on the basis of the shifted voltage-current characteristic, thereby a present open circuit voltage of the battery is computed.

Method and apparatus for estimating terminal voltage of battery, method and apparatus for computing open circuit voltage of battery, and method and apparatus for computing battery capacity

In an apparatus for measuring a pure resistance of an in-vehicle battery, a terminal voltage and a discharging current of the battery are measured when the discharging current flows from the battery. A first approximate equation of a voltage-current characteristic curve is acquired for an increasing discharging current, and a second approximate equation is the voltage-current characteristic curve is acquired for a decreasing discharging current. Two points providing equal synthesized resistances each composed of the pure resistance and polarization resistance component are set on the voltage-current characteristic curves represented by the first and the second approximate equations, respectively. The gradients between the two points in each of the voltage-current characteristic curves are corrected to provide two corrected gradients each exclusive of a voltage drop due to the polarization resistance component. The two corrected gradients are averaged to provide an average value which is measured as a pure resistance of the battery.

Method and apparatus for measuring pure resistance of in-vehicle battery

A battery capacity detection system according to the invention is provided with: a temperature sensor for sensing a temperature of the battery; a full-charge voltage calculation section for calculating a voltage of the battery in a full charge state by using the temperature sensed by the temperature sensor; and an SOC calculation section for calculating an SOC of the battery by using the voltage of the battery in the full charge state calculated by using the temperature in the full-charge voltage calculation processing section.

Battery capacity detection system with temperature correction

The present invention provides conductive materials having high ionic conductivity and cationic transference number, small amount of polarization and good flexibility. The conductive material comprises high molecular compounds and alkalisiloxyaluminate.

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Shizuoka, Japan

Hideaki Kamohara