A battery management system includes at least one cell monitoring unit with a plurality of cell voltage terminals, supply lines coupled to the cell voltage terminals, and a cell monitoring circuit made of a plurality of electronic semiconductor modules connected in parallel via the supply lines. The battery management system is configured to monitor a plurality of battery cells via the cell monitoring unit. The battery cells are in each case connected on both sides with their respective positive battery cell terminal and negative battery cell terminal to the battery management system via the cell voltage terminals. Furthermore, one or several supply lines are provided with a melt fuse so that in each battery cell that is connected to the battery management system at least one supply line coupled to the battery cell comprises a melt fuse in its current path.

Battery management circuits include a first charging channel, a Cuk circuit, and a communication control circuit. A battery is charged through the first charging channel based on charging voltage and/or charging current provided by a power supply device. The battery includes a first cell and a second cell coupled in series. The communication control circuit is configured to communicate with the power supply device, to make magnitude of the charging voltage and/or charging current provided by the power supply device match a present charging stage of the battery, and the communication control circuit is further configured to send a drive signal to the Cuk circuit to drive the Cuk circuit to work, to make energy of the first cell and the second cell be transferred through the Cuk circuit to balance voltage of the first cell and voltage of the second cell.

A multi-cell battery pack charging system adjusts each battery cell's charging current to synchronize the completion of charge. The battery pack is charged as a whole, and need only be charged once, and without requiring charge shuttling, resistive charge balancing or inductive charge dumping. Charging current to each battery cell is based on voltage matching of the battery cells being charged, lower voltage battery cells being given more charge current until there is a voltage match to the other series connected battery cells. Additional charge may be given to higher capacity cells of the battery pack during the voltage matching and charging process.

A charger circuit which supplies a charging power to charge a battery circuit, includes: a conversion switch circuit, at least one capacitor and a conversion control circuit. The conversion switch circuit is coupled between a charging power and a ground level and includes conversion switches connected in series. The conversion switch circuit has battery voltage balancing nodes electrically connected to the battery circuit, such that each battery is electrically connected between two of the battery voltage balancing nodes. The conversion control circuit is coupled to the conversion switch circuit and provides operation signals to the conversion switch circuit, to respectively control the corresponding conversion switches, so that the capacitor is periodically connected in parallel to each battery of the battery circuit, thereby balancing the battery voltages of the batteries.

A method (900) of reducing variation of an energy storage capacity of a battery across its cycle life is disclosed. The method can include the step (901) of monitoring one or more voltages of one or more cells of a battery for a predetermined discharge usage time. Where a profile of the one or more voltages during the predetermined discharge usage time meets a predefined usage criterion, the method can include the step (907) of increasing a discharge voltage limit of the one or more cells. An energy management circuit (614) can be configured with a control circuit (702) operable to increase the discharge limit and to limit discharge of the cells when the discharge limit is reached.

A battery pack for housing plural secondary batteries inside a case includes a battery management unit for managing states of the plural secondary batteries, an information transfer circuit which is connected to the battery management unit and transfers information about the secondary batteries to the battery management unit, and a diagnostic circuit which is branched and formed from the information transfer circuit and is extended to an outer surface of the case.

Provided are a charge equalization apparatus for a battery string. According to the exemplary embodiments of the present invention, the charge equalization apparatus are modularized by being divided into the master unit and the slave unit, such that the charge equalization apparatus may be expanded and contracted independent of the number of batteries, the circuits are separated for each module, such that the circuits may be easily implemented, and when the circuits are damaged, only the damaged module is replaced, such that the effective countermeasure may be performed.

The present invention relates to a battery system which has a hybrid battery which comprises a first energy storage source having a plurality of first energy storage cells and comprises a second energy storage source which is connected in series with the first energy storage source and has a plurality of second energy storage cells which are different from the first energy storage cells. Furthermore, the battery system has an inverter which is connected at the input end to the battery and is designed to convert a DC voltage which is supplied to the input end into an, in particular polyphase, AC voltage which is produced at the output end. The battery system also has a control unit which is designed to operate the inverter in a first functional mode or in a second functional mode or in a third functional mode by controlling a plurality of semiconductor switches of the inverter. In the first functional mode, the inverter converts a DC voltage which is provided by the first energy storage source and is supplied to the input end into the AC voltage which is produced at the output end. In the second functional mode, the inverter converts a DC voltage which is provided by the second energy storage source and is supplied to the input end into the AC voltage which is produced at the output end. In the third functional mode, the inverter converts a DC voltage which is provided by a series circuit comprising the first energy storage source and the second energy storage source and is supplied at the input end into the AC voltage which is produced at the output end.

The present invention aims to efficiently use all of a plurality of capacitors connected in series, and control a voltage held by a capacitor unit according to environmental temperature. A switch element inserted into a charging path leading to the capacitor unit, and a switch control part controlling the opening and closing of the switch element, are provided. The switch control part includes: a first voltage divider circuit that includes a pair of resistor elements, and that produces and outputs a voltage that is a fraction of the voltage held by the capacitor unit; and a comparison result output circuit that controls the opening and closing of the switch element based on the result of comparing a potential output from the first voltage divider circuit and a predetermined potential. The pair of resistor elements are different from each other in terms of temperature dependency of resistance values thereof.

A battery pack, power tool, and power tool combination. The battery pack includes one or more battery cells, a first terminal electrically connected to the one or more battery cells, a high current power supply terminal, a power switch electrically connected between the one or more battery cells and the high current power supply terminal, and a low current power supply terminal electrically connected to the one or more battery cells. The first terminal and low current power supply terminal are operable to provide a substantially continuous low current to the power tool during a normal operating state of the battery pack. The battery pack also includes a controller operable to control the power switch to provide high current power through the high current power supply terminal in response to a call for power from the power tool.