Abstract: A method of displaying the full-charge-state of a battery according to the invention is characterized in that the displaying is retarded by a predetermined period of time after the full-charge-state is detected. According to the method, the delay time is so determined that the battery which requires a shorter charging time needed to full-charge the battery has a longer delay time period than the battery requiring a longer charging time.

Abstract: A method of displaying the full-charge-state of a battery according to the invention is characterized in that the displaying is retarded by a predetermined period of time after the full-charge-state is detected. According to the method, the delay time is so determined that the battery which requires a shorter charging time needed to full-charge the battery has a longer delay time period than the battery requiring a longer charging time.

Abstract: A battery pack having at least one rechargeable battery and a secondary coil, which is electromagnetically coupled to a primary coil contained inside of a charging stand. The battery pack also includes a control circuit which controls electric power induced in the secondary coil for charging the rechargeable batteries. The secondary coil of the battery pack is positioned close to the bottom of a battery pack case with its center axis oriented along the elongated direction of the case. The charging stand contains the primary coil, which is located so as to be close to the secondary coil when the battery pack is mounted on the charging stand.

Abstract: A battery pack comprises at least one rechargeable battery, a secondary coil which is magnetically coupled to a primary coil housed in a charging stand, and a control circuit which controls power induced in the secondary coil and charges the rechargeable battery. Alternating current (AC) generated in the secondary coil housed in the battery pack is controlled by the control circuit to charge the rechargeable battery.

Abstract: The battery charging apparatus is provided with a charging power supply for electric power to charge rechargeable batteries, a first battery attachment section positioned close to the power supply, a second battery attachment section positioned further away from the power supply, and a charging controller which fully charges a rechargeable battery in the first battery attachment section faster than a rechargeable battery in the second battery attachment section.

Abstract: A charging apparatus charges a battery assembly including a plurality of secondary batteries. After the charging apparatus detects a full charge level, the apparatus stops charging. Then, when the charge level of the battery assembly falls below a predetermined charge level, the charging apparatus resumes charging in order to maintain the secondary battery assembly at a full charge level. The charging apparatus monitors the charging after charging is resumed. When the charging apparatus detects that the charging process after resumption of charging is abnormal, the apparatus modifies the charging. For example, when the battery assembly includes a malfunctioning secondary battery causing an abnormal charge resumption, the apparatus modifies the charging to prevent the other normal secondary batteries in the secondary battery assembly from being overcharged to avoid deterioration.

Abstract: A battery charging circuit performs rapid charging without over-charging followed by supplementary charging to insure a fully charged rechargeable battery. The amount of supplementary charging is increased at low ambient temperatures and decreased at high temperatures. A primary charging circuit means for rapid charging and a supplementary charging circuit means for supplementary charging are provided. A temperature sensing means measures ambient temperature during rapid charging to establish the amount of supplementary charging required.

Abstract: A method and apparatus for protecting a secondary battery initially judges whether or not the secondary battery, previously charged to a capacity more than a predetermined capacity, has been discharged to a capacity less than the predetermined capacity within a predetermined time. Then, compulsorily discharging at the secondary battery is effected until it has a capacity less than the predetermined capacity when it is judged that the secondary battery has not been discharged to a capacity less than the predetermined capacity.

Abstract: A battery charger has a battery capacity detector for detecting the remaining battery capacity and a timer setter for controlling the timer setting that determines the battery charging time based on the results from the battery capacity detector. The battery capacity detector measures the battery voltage, the battery constant current charging time, or the battery capacity. The timer includes a protection timer to forcibly end battery charging and a constant current charging timer to establish the constant current charging interval.

Abstract: A charging apparatus charges a secondary battery, while controlling an output voltage of the charging apparatus to maintain the effective charging voltage at a substantially constant predetermined value at which the secondary battery is actually charged. Such a method prevents the secondary battery from being overcharged with a overvoltage, and enables the charging time to be short.

Abstract: A secondary battery is charged with a constant voltage, while a charging current generated by the application of the constant voltage is monitored. After the charging current becomes smaller than a predetermined current value, an open circuit voltage of the secondary battery is sampled at a predetermined interval while substantially stopping charging. Charging is completed, when either a voltage difference between a terminal voltage of the secondary battery and the sampled open circuit voltage becomes smaller than a predetermined voltage difference value, the sampled open circuit voltage becomes bigger than a predetermined voltage value, or, a remaining charging time of a timer which is calculated based on the sampled open circuit voltage has elapsed. The method shortens the charging time and enables the correct detection of the fully charged state.

Abstract: A rechargeable battery is supplementary charged after peak battery voltage is detected. The time interval for supplementary charging is variable and set as a function of the time to peak voltage or charging current. The longer the charging time or the higher the charging current, the longer the supplementary charging timer interval.

Abstract: By sensing battery voltage and temperature, a battery charger fully charges a battery even when a load is attached during charging. A control circuit suspends charging by detecting a change in battery voltage near a peak voltage. A charge restart section restarts charging depending on computations performed on the output from a temperature detection section. After charging is stopped, it is restarted if battery temperature is less than a set value, or if the rate of battery temperature rise is less than a set rate.