Abstract: A method of changing a secondary battery, a method of calculating a remaining capacity rate of the secondary battery, and a battery pack are provided. The method of charging a secondary battery includes the steps of: performing a detection of a charging rate of the secondary battery using an integrating method in which a battery capacity is calculated by integrating a current value or a power value of the secondary battery for a certain period of time, and a detection of the charging rate of the secondary battery using a voltage method in which a voltage value of the secondary battery is measured and the charging rate is calculated based on a correlation between the voltage value and the charging rate; and performing a weighted addition of the charging rate detected by the integrating method and the charging rate detected by the voltage method in accordance with the charging rate of the secondary battery, whereby detecting a final charging rate.

Abstract: A battery pack having a secondary battery; a measurement unit measuring a terminal voltage and a current of the secondary battery; a protection unit preventing the secondary battery from being overcharged when the terminal voltage measured by the measurement unit is equal to or higher than an overcharge detection voltage; and a control unit receiving the terminal voltage and current measured by the measurement unit, the control unit having a first mode and a second mode in which current is less consumed than the first mode. A voltage in a range of from a full charge voltage to less than the overcharge detection voltage is defined as a voltage threshold. The control unit changes from the first mode to the second mode when a state in which a transition requirement is satisfied lasts for a predetermined period of time.

Abstract: A battery pack having a secondary battery and a circuit that controls charging and discharging of the secondary battery is provided. The battery pack has a computer that communicates with another computer disposed in a charging device, authenticate the charging device, and calculates remaining capacity information of the secondary battery. When the computer has not successfully authenticated the charging device and has detected that the secondary battery has been charged in a predetermined manner, the computer forcibly sets the remaining capacity information to “no remaining capacity”.

Abstract: A battery pack having a secondary battery and a circuit that controls charging and discharging of the secondary battery is provided. The battery pack has a computer and a charging control section. The computer communicates with another computer disposed in a charging device and authenticates the charging device. The charging control section, controlled by the computer, supplies a charging current to the secondary battery when the charging device has been successfully authenticated and shuts off the charging current when the charging device has not been successfully authenticated.

Abstract: A remaining capacity calculation method for a secondary battery and a battery pack are provided. Dischargeable electric power is accurately calculated and accuracy of a remaining capacity rate found by an electric power integration method may be improved by providing a remaining capacity calculation method for a secondary battery. The method includes calculating a consumed electric power by way of integration of voltage and current measured at a preset time interval when using the secondary battery; calculating an available dischargeable electric power by subtracting an energy loss and unavailable energy from a discharge electric power of the secondary battery; and calculating a remaining capacity rate from a ratio between the calculated electric power and the dischargeable electric power.

Abstract: A method of changing a secondary battery, a method of calculating a remaining capacity rate of the secondary battery, and a battery pack are provided. The method of charging a secondary battery includes the steps of: performing a detection of a charging rate of the secondary battery using an integrating method in which a battery capacity is calculated by integrating a current value or a power value of the secondary battery for a certain period of time, and a detection of the charging rate of the secondary battery using a voltage method in which a voltage value of the secondary battery is measured and the charging rate is calculated based on a correlation between the voltage value and the charging rate; and performing a weighted addition of the charging rate detected by the integrating method and the charging rate detected by the voltage method in accordance with the charging rate of the secondary battery, whereby detecting a final charging rate.