Fujitsu Corporation

Yoshiro Takeda

Hidekiyo Ozawa

Mitsuo Saeki

Nobuo Tanaka

Toshiaki Tsukuni

Toshihiro Miyamoto

Kazuhito Fukuoka

Masami Itoyama

An electronic apparatus includes a processor and a memory coupled to the processor. The processor executes a process including calculating a first accumulated time during which the battery device feeds power to the electronic apparatus while being attached to the electronic apparatus in a first attachment state in which a first surface of the battery device faces a reference surface provided in the electronic apparatus, calculating a second accumulated time during which the battery device feeds power to the electronic apparatus while being attached to the electronic apparatus in a second attachment state in which a second surface of the battery device faces the reference surface, the second surface being different from the first surface, and providing an instruction to change an attachment state of the battery device when a difference between the first accumulated time and the second accumulated time exceeds a given time.

Electronic apparatus and method for changing an attachment state of a battery pack

The device for charging a secondary battery, comprises: a measuring circuit for measuring the terminal voltage of the battery; a control circuit for controlling a charging current fed through the battery; and an abnormality determining portion which starts a preliminary charging of the battery (S ), finishes the charging (S ) when the voltage of the battery has reached a first threshold value which is decided based on the normal-state upper limit of the internal resistance and the current of the battery (S ), measures the open-circuit voltage of the battery after finishing the charging, determines that the battery is abnormal when the open-circuit voltage is less than a second threshold value (S ), determines that the battery is abnormal when the open-circuit voltage is larger than a third threshold value for detecting that the battery is abnormal (S ), and indicates that the battery is abnormal (S ).

Device and method for charging a secondary battery

A battery unit includes a plurality of cells connected in parallel with one another, and a switch connected in series with at least one of the cells. The battery unit further includes a control circuit for controlling the on or off state of the switch, and a voltage detection terminal at which a voltage produced by a cell, to which the switch is connected, is developed. The switch can be turned off even with the battery unit connected to a load. A cell in series with which the switch is connected is disconnected from the load. In this state, the state of the cell can be detected through the voltage detection terminal. Even when a resistor is substituted for the switch, the same advantage can be provided. Moreover, the battery unit is freely detachably attached to a main unit of an information processing apparatus. The battery unit then supplies power to the main unit. A power supply control circuit for requesting notification of the state of each cell in the battery unit is incorporated in the main unit. The states of the cells can therefore be detected mutually independently.

Battery unit and information processing system having battery unit mounted therein

A protection circuit is used for a battery unit which has a plurality of cell parts coupled in parallel, and first and second power supplying terminals, where each of the cell parts includes a plurality of battery cells coupled in series, and first and second terminals respectively coupled to the first and second power supplying terminals. The protection circuit includes a plurality of switching elements making an electrical connection to the first terminal of a corresponding one of the cell parts and the first power supplying terminal, and disconnecting the electrical connection in response to an active signal, and a voltage monitoring circuit outputting the active signal to the switching elements when a voltage of at least one battery cell within one cell part falls outside a predetermined range, independently with respect to each of the cell parts.

Protection circuit and battery unit

A battery capacity predicting method predicts a remaining capacity of a battery unit including a plurality of battery cells connected in series in an apparatus which uses the battery unit. The battery capacity predicting method includes the steps of comparing output voltages of each of the battery cells, and predicting the remaining capacity of the battery unit based on at least one of a minimum voltage and a maximum voltage out of the compared output voltages of the battery cells.

Battery capacity predicting method, battery unit and apparatus using

A method for controlling a secondary battery constant current charging method and a control apparatus therefor, which measures battery voltage (V), a change in battery voltage per unit time (.DELTA.V/.DELTA.t), a decrease in battery voltage (-.DELTA.V) from a maximum value, battery temperature (T), and/or a change in battery temperature per unit time (.DELTA.T/.DELTA.t); and stops the battery charging when .DELTA.V/.DELTA.t is greater than or equal to a predetermined value after the passage of a predetermined time t.sub.S, or when .DELTA.V/.DELTA.t and .DELTA.T/.DELTA.t are greater than or equal to predetermined values, or when .DELTA.V/.DELTA.t and T are greater than or equal to predetermined values, or when V is greater than or equal to a maximum value V.sub.P, or when either the -.DELTA.V or T is greater than or equal to a predetermined value.

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Yokohama, Japan

Yoshiro Takeda