A charger comprises an input circuit that receives power from a power source, a converter circuit, an output circuit, and a switching circuit. The converter circuit is connected between the input circuit and a signal ground of the charger and converts the power from a first voltage to a second voltage. The signal ground is connected to a chassis ground of the charger. The output circuit is connected between an output of the converter circuit and the signal ground and the chassis ground, and outputs the second voltage to an output connector of the charger. The switching circuit is connected between the output of the input circuit and an electrically conducting casing of the output connector, and controls the converter circuit. The switching circuit and the electrically conducting casing of the output connector are not connected to the signal ground and the chassis ground of the charger.

An electronic device including a voltage divider adaptively changing a voltage division ratio is provided. The electronic device comprises a rechargeable battery; a connector configured to connected the electronic device with an external electronic device; a voltage divider comprising a plurality of capacitors and a plurality of switches for switching an electrical path between each of the plurality of capacitors and the rechargeable battery, wherein the voltage divider is configured to provide three or more voltage division ratios; and a processor operably coupled with the voltage divider and the connector, wherein the processor is configured to: receive an indicator indicating a first voltage of a first power from the external electronic device; select a voltage division ratio from the three or more division ratios, based at least in part on the indicator; and control the plurality of switches on the basis of the selected voltage division ratio, and wherein the voltage divider is configured to: charge a rechargeable battery with a second voltage by dividing the first voltage according to the selected voltage division ratio.

When an abnormality occurs in a first voltage detector (4a), a control circuit (7) in an uninterruptible power supply device controls an inverter (3) in synchronization with an output signal (VI2D) from a second voltage detector (4b) to match a phase of a two-phase AC voltage (VO1, VO2) output from the inverter (3) with a phase of a two-phase AC voltage (VI1, VI2) supplied from a commercial AC power supply (51), and then turns on a semiconductor switch pair (S9, S10) and a bypass switch pair (S7, S8). Accordingly, even when an abnormality occurs in the first voltage detector (4a), the two-phase AC voltage can be supplied to a load (53) without instantaneous interruption.

A direct-current to direct-current (DC-DC) converter is provided for use in an electric vehicle. The DC-DC converter is configured to be used as either a resonant converter or a PWM converter in the electric vehicle. For example, the DC-DC converter may operate as a resonant converter in which a current is sequentially applied through a first conversion unit, a resonant tank, a transformation unit, and a second conversion unit. The DC-DC converter may further operate as a pulse width modulation (PWM) converter in which a current is sequentially applied through the second conversion unit, the transformation unit, and a third conversion unit.

An inventive testing method is intended for testing a battery pack unit including: a battery pack including a plurality of cells electrically connected to each other; and a duct assembly through which a coolant is supplied to the cells of the battery pack. The testing method includes: a) charging the battery pack under predetermined conditions while supplying the coolant to the duct assembly; b) acquiring temperature information on the cells at predetermined time intervals during step a); and c) determining whether a difference between the highest and lowest ones of the temperatures of the cells measured at substantially the same time is equal to or greater than a predetermined reference temperature difference on the basis of the temperature information acquired in step b).

An adapter (10) and a charging control method, the adapter (10) comprising: a power conversion unit (11), used for converting an inputted alternating current so as to obtain an output voltage and an output current of the adapter (10), the output current of the adapter (10) being an alternating current or a pulsed direct current; a voltage holding unit (12), an input end of the voltage holding unit (12) being connected to the power conversion unit (11), the voltage holding unit (12) being used for obtaining an input voltage having a pulsed waveform from the power conversion unit (11) and converting the input voltage having the pulsed waveform into a target voltage, an output end of the voltage holding unit (12) being connected to a device in the adapter (10), the target voltage being used to power the device in the adapter (10), a peak value of the target voltage being between the lowest operating voltage and the highest operating voltage of the device. The adapter (10) reduces lithium separation in batteries, and increases the service life of batteries.

A battery charger circuit having a regulator controller configured to control the switching transistors of a switching voltage regulator. A power path switch is disposed intermediate an output of the switching voltage regulator and a terminal of a battery to be charged, with the power path switch including at least two transistor segments having common respective drain electrodes, common respective source electrodes and separate respective gate electrodes. A power path switch controller operates to sequentially turn ON the at least two transistor segments of the power path switch, preferably in the order of a decreasing ON resistance.

An electric power storage system for a vehicle includes a temperature sensor configured to detect a temperature of a battery, a battery heater, a charger connectable with an external power supply and configured to deliver external power to the battery and the battery heater, and a controller. In the system, a first electric power is supplied to the battery heater when the state of charge of the battery is larger than a predetermined value and the temperature of the battery is equal to or lower than the predetermined temperature, and a second electric power is supplied to the battery heater when the state of charge of the battery is equal to or smaller than the predetermined value and the temperature of the battery is equal to or lower than the predetermined temperature. The first electric power is smaller than the second electric power.

A method for charging a battery may comprise: setting an initial low charge current level; repetitively interrupting charging in a periodic cycle, and: measuring an open circuit battery voltage when charging is interrupted, determining from the open circuit battery voltage a corresponding predetermined charging current; applying the predetermined charging current; and repeating the periodic cycle. A method may also comprise: setting an initial charge current level, measuring the supply voltage, and decreasing the charge current level if the measured supply voltage is less than a predetermined voltage.

A battery charger circuit having a regulator controller configured to control the switching transistors of a switching voltage regulator. A power path switch is disposed intermediate an output of the switching voltage regulator and a terminal of a battery to be charged, with the power path switch including at least two transistor segments having common respective drain electrodes, common respective source electrodes and separate respective gate electrodes. A power path switch controller operates to sequentially turn ON the at least two transistor segments of the power path switch, preferably in the order of a decreasing ON resistance.