Abstract: An electrical power supply system for powering an electric load of a vehicle includes a main battery, a support battery and a battery control module. The battery control module includes a first terminal for connection to the main battery, a second terminal for connection to the support battery and a third terminal for connecting to the electric load. A switch is arranged between said second terminal and said third terminal. The battery control module is arranged to connect the support battery to the load by turning the switch conducting in case the voltage at the third terminal drops below a predetermined voltage. The system provides the automatic activation of a support energy source when the output voltage falls below a specified voltage threshold. The support battery supports the main battery when needed or acts as a redundant power source.

Abstract: A charge and discharge control device includes: a coordination unit which generates coordination information for calculating an output value which each storage battery is caused to output, based on a bus voltage value and a target voltage value; a string output calculating unit which calculates, based on the coordination information, an output target value indicating the output value which the storage battery is caused to output to maintain the bus voltage value at the target voltage value; and a control unit which causes, among the storage batteries, a storage battery corresponding to the calculated output target value to output an output having a magnitude indicated by the calculated output target value, wherein the coordination unit generates the coordination information to avoid simultaneous presence of a storage battery that outputs an output in a charge direction and a storage battery that outputs an output in a discharge direction.

Abstract: The controller calculates a first limit based on received information about the battery packs and the schedule for charging and discharging plan, and supplies the first limit which serves as a control command to a master battery management unit (BMU), a master BMU receives the first limit. The master BMU sets and distributes the second limit to each one of local battery management function blocks in the battery packs. As a result, each BMU receives the second limit respectively. Then, the each BMU supplies the third limit to a bidirectional power source circuit, respectively, based on failure information FAIL and capacity information SOC of the battery in the battery pack.

Abstract: A power device including a power circuit assembly, a first plug assembly, and a second plug assembly is described herein. The first plug assembly is coupled to the power circuit assembly for transmitting power from a power source to the power circuit assembly at a first voltage. The second plug assembly is coupled to the power circuit assembly for controllably transmitting power from the power source to the power circuit assembly at a second voltage and at a third voltage.

Abstract: A system for charging and discharging batteries includes a battery module, an adapter, a charger, and an electronic device electrically connected to the charger and the battery module. The battery module includes a first cell battery, a second cell battery, and a first switch electrically connected to the first and second battery cells. The adapter receives an AC voltage, and converts the AC voltage to a DC voltage. The charger receives the DC voltage, and charges the battery module accordingly. The electronic device is electrically connected to the charger and the battery module. When the charger charges the battery module, the first switch is switched to electrically connect the first and second battery cells with the charger in series. When the battery module discharges to the electronic device, the first switch is switched to electrically connect the first and second battery cells with the electronic device in parallel.

Abstract: An energy management system has an integration control portion that performs control to charge a storage battery with a power of such an amount that a power consumption including a power supplied by a supply portion is equal to or smaller than a target value indicated by power consumption target information recorded in a recording portion when a power consumption detected by a detection portion is smaller than the target value, and to supply a building with a power with which the storage battery is charged such that the power consumption including the power supplied by the supply portion coincides in amount with a power equal to or smaller than the target value indicated by the power consumption target information recorded in the recording portion when the power consumption detected by the detection portion is larger than the target value.

Abstract: A circuit for connecting a first accumulator line to a second accumulator line from an accumulator is described. The accumulator is provided for charging and discharging electrical energy via the accumulator lines. Each accumulator line has a positive pole and a negative pole for charging and discharging electrical energy. The circuit has at least one first switch which is provided for disconnecting and connecting two similar poles of the two accumulator lines.

Abstract: A method for charging an assembled battery including series circuits connected in parallel, each of the series circuits including series-connected lead storage batteries, using a single charger is provided. The method includes: a first step of obtaining a first index value, corresponding to a resistance value of a first series circuit with a correlative relationship, the first series circuit having a lowest resistance value; a second step of obtaining a second index value corresponding to a resistance value of a second series circuit with a correlative relationship, the second series circuit having a highest resistance value; a third step of performing normal charging, in which the assembled battery is charged with a first amount of charge corresponding to the first index value; and a fourth step of performing refresh charging, in which the assembled battery is charged with a second amount of charge corresponding to the second index value.

Abstract: A power source apparatus includes first equalizing circuits to control remaining charge capacity variation among a plurality of battery units, and second equalizing circuits to control remaining charge capacity variation among all the series-connected battery packs that make up each battery unit. A first equalizing circuit connects each battery unit with an output line OL through a first series circuit made up of a first limiting resistor and first equalizing switch. Remaining charge capacity variation is equalized among all the battery units by the first equalizing circuits, and remaining charge capacity variation between battery packs in each battery unit is controlled by the second equalizing circuits.

Abstract: A system that balances voltages between battery banks. The system includes battery banks, including a first bank and a second bank, and a first capacitor. The system also includes a first set of switching devices which selectively couple first and second terminals of the first capacitor to first and second terminals of the first bank, and to first and second terminals of the second bank. The system includes a clocking circuit which generates clock signals with substantially non-overlapping first and second clock phases. This clocking circuit is configured so that during the first phase the first and second terminals of the first capacitor are coupled to the first and second terminals of the first bank, respectively, and during the second phase the first and second terminals of the first capacitor are coupled to the first and second terminals of the second bank, respectively.

Abstract: A battery pack includes a first battery and a second battery connected electrically in parallel and performing charge and discharge, and a heater generating heat. The first battery can perform charge and discharge with a current larger than that of the second battery. The second battery has an electric storage capacity larger than that of the first battery. The heater is placed at a position closer to the first battery than the second battery.

Abstract: Systems and methods for simultaneously charging two or more cell strings of a hybrid battery system from a shared input current path to the battery system. An input common charging current may be limited to the smallest maximum allowable charging current value of multiple battery cell strings of a hybrid battery system, or may be provided as the greater of the maximum allowable charging currents of multiple battery cell strings of a hybrid battery system with current supplied to individual cell strings that require less than the maximum current being individually controlled so as not to exceed the maximum allowable current for each of the individual cell strings of the hybrid battery system.

Abstract: A method and system for determining the temperature of cells in a battery pack, without using temperature sensors, by measuring the impedance of the cells and using the impedance to determine the temperature. An AC voltage signal is applied to the battery pack, and a time sample of voltage and current data is obtained. The voltage and current data is narrowed down to a simultaneous time window of interest, and a fast fourier transformation is performed on the windowed voltage and current data to identify voltage and current magnitudes at one or more specific frequencies. The voltage and current magnitudes are used to determine the impedance at the one or more frequencies. Finally, the impedance is used to determine the temperature of the cell or cells using a look-up table, where the impedance, the frequency, and a state of charge are used as input parameters for the look-up.

Abstract: A control device of an electric power supply apparatus controls a voltage applied to an inverter to fall within a voltage range between a first voltage that is the voltage of one of a first electric power supply and a second electric power supply and a second voltage that is the sum of the voltage of the first electric power supply and the voltage of the second electric power supply, by alternately switching between a series state in which a current loop that connects the first electric power supply, the second electric power supply, and a reactor in series with the inverter is formed, and a parallel state in which the first electric power supply and the second electric power supply are connected in parallel with the inverter as an electric load.

Abstract: A battery power system includes a number of battery modules. Each battery module includes a number of battery cells, a management circuit positioned at a first side of the battery module, and a heat source positioned at a second side of the battery module and opposite to the first side. The management circuit is electrically connected to and manages charging and discharging of the cells of the corresponding battery module. The heat source is thermally coupled to the cells of the corresponding battery module and dissipates heat generated by the cells of the corresponding battery module. The battery modules are arranged in two lines, and the first sides of the battery modules in one line are positioned adjacent to and face the first sides of the battery modules in another line.

Abstract: A regulating device includes: a generating means for generating an output voltage from an input voltage; a plurality of first switches, respectively corresponding to the plural storage battery units connected in parallel, with each of said first switches interposed between the corresponding storage battery unit and the input side of the generating means; a plurality of second switches, respectively corresponding to the plural storage battery units, with each of said second switches interposed between the corresponding storage battery unit and the output side of the generating means; a detecting means for detecting the voltage of each of the plural storage battery units; and, a control means that, referring to the result of detection from the detecting means, identifies first storage battery units whose voltages are higher than the average value of voltage of the plural storage battery units and second storage battery units whose voltages are lower than the average value, from the plural storage battery units,

Abstract: A field device for determining and/or monitoring a physical or chemical, process variable in automation technology. The field device comprises: at least one microcontroller; a supply unit of limited capacity as primary voltage supply; and a detection circuit, which signals the microcontroller of a failure of the supply unit so early by means of a detection signal that sufficient time is available to take suitable safety measures, in order to avoid loss of data. The detection circuit is so embodied that a reference voltage required for detection of a voltage decline of the supply unit has an almost constant offset from the supply voltage of the supply unit and adjusts to the supply voltage, until the detection circuit, in the case of an abrupt subceeding of the reference voltage, or an abrupt voltage decline of the supply voltage, sends a detection signal to the microcontroller.

Abstract: A voltage equalization device of a power storage device provided with battery packs in which a plurality of secondary cells are connected, power converters provided in association with the battery packs, and controllers that control the power converters, and in which the battery packs are connected in parallel via the individual power converters includes a decision portion and a voltage-adjusting portion. The decision portion obtains battery-pack information regarding the states of charge/discharge of the individual battery packs and decides, for each battery pack, whether or not to perform voltage adjustment on the basis of the battery-pack information. When the decision portion decides that the voltage adjustment is to be performed, the voltage-adjusting portion generates offset instructions for adjusting the states of charge/discharge and outputs the offset instructions to the controllers of the power converters associated with the battery packs.

Abstract: A charge control apparatus which includes charger 120 whose output voltage is variable and to which batteries 101A and 101B are connected in parallel, further includes: current detectors 105A and 105B that detect charging currents flowing to batteries 101A and 101B, and output the detected current values; maximum value detector 130 that selects the maximum value from among the output values of current detectors 105A and 105B, and outputs the selected value; and controller 140 that controls the output voltage of charger 120 such that the output value of maximum value detector 130 matches a setting value.

Abstract: A control apparatus for a vehicle battery having a first battery and a second battery connected in parallel is provided. Each of the first and second batteries is provided with a relay operating between an allowing state in which charge from the power supply section is allowed and in a non-allowing state in which the charge is not allowed. The control apparatus includes a controller performing charge processing in which, when a voltage difference exists between the first battery and the second battery, the relay provided for one of the batteries having a lower voltage is set at the allowing state to charge only the one of the batteries, and when the charge causes the voltage of the one of the batteries to be equal to the voltage of the other of the batteries, both the relays provided for the one and the other of the batteries are set at the allowing state to charge the one and the other of the batteries.

Abstract: An adjusting device that is connected to a load and to a plurality of storage battery units that are connected together in parallel and that adjusts voltage differences among the plurality of storage battery units includes: for each of the storage battery units, a switch that is provided between a storage battery unit and the load that is turned ON during detection intervals for detecting current from the storage battery unit, a detection means that detects the current supplied from each of the storage battery units during the detection interval, and an adjusting means that, based on the detection results of the detection means, controls the ON/OFF states of switches during the adjustment intervals for adjusting voltage differences such that the voltage differences among the plurality of storage battery units are decreased.

Abstract: An electricity storage system comprising: a plurality of cartridges connected together in parallel, each cartridge comprising a plurality of cells connected together, and a circuit for preventing cross current, which restricts the current in each cartridge so as to cause the current to flow in one direction selected from a discharge direction and a charge direction, wherein said cartridges connected together in parallel are simultaneously charged with a direct current voltage converted from a commercial voltage, or said cartridges connected together in parallel are caused to discharge simultaneously so that said electricity storage system outputs a commercial voltage.

Abstract: Disclosed is an apparatus for controlling the connection of a plurality of battery packs including a switching unit provided on a charge/discharge path of each battery pack to selectively open and close the charge/discharge path, a first control unit provided for each battery pack to determine the state of charge (SOC) of each battery pack and control the opening/closing of the switching unit, and a second control unit to receive the determined SOC of each battery pack from the first control unit, group battery packs having a predetermined range of SOCs, select a group containing a largest number of battery packs, connect the battery packs of the selected group in parallel, charge or discharge the parallel-connected battery packs so that a difference in SOC between the parallel-connected battery packs and the non-connected battery pack falls within a predetermined range, and connect the non-connected battery pack thereto in parallel.

Abstract: A battery pack includes: a first battery cell group including at least one high capacity battery cell; and a second battery cell group including at least one high output battery cell and being coupled in parallel to the first battery cell group, wherein the high output battery cell is configured to output a greater current than the high capacity battery cell, the high capacity battery cell is configured to store a greater amount of electric energy compared to the high output battery cell, and the battery pack is configured to operate in one of operational modes including: a high capacity mode for outputting electric energy stored in the first battery cell group; a high output mode for outputting electric energy stored in the second battery cell group; and a mutual charge mode for charging the first battery cell group or the second battery cell group.

Abstract: A system and method of cell balancing of a battery pack using a cell balancing device of a battery pack is provided and includes a controller that detects an inter-cell voltage deviation in the battery pack. In addition, the controller is configured to determine whether to perform cell balancing on the battery pack and inactivate a relay connected with the battery pack. The controller is further configured to perform cell balancing in the battery pack.

Abstract: A method for charge balancing of battery cells to be connected in parallel of a battery module includes making contact with terminals of the battery cells and measuring quiescent voltages of the battery cells; determining capacitances and internal resistances of the battery cells for determining a required duration for the charge balancing; and short-circuiting the battery cells in pairs at a low resistance and implementing the charge balancing via the internal resistances of the battery cells short-circuited in pairs. The method further includes ending the contact-making after the required duration; and producing a parallel circuit between the battery cells by fastening connecting lugs on respective terminals of the battery cells.

Abstract: Rechargeable batteries are used as a power supply in the most varied electrical devices. Parallel to this, connections with other energy sources are frequently available, at least for part of the time, in order to charge the rechargeable batteries during this time. Particularly efficient lithium ion batteries have the problem that short charging/discharging cycles cause them to age just as much as long cycles, during which the user can derive greater benefit from them. It is the task of the invention to ensure particularly effective use of rechargeable batteries during charging/discharging cycles of the most varied duration. This is achieved in that the rechargeable battery is divided into cells, of which only one is charged, in each instance, and the others stand ready to provide energy. If the network voltage stops, charging of the cell just being charged is completed from the other cells.

Abstract: A first monitor circuit 50 and a second monitor circuit 60 each having an identical configuration are provided in a voltage monitor. A threshold switching section 41 switches a threshold of each of switching units 51 and 61 provided in the respective monitor circuits 50 and 60 to a same value. Each of comparators 53 and 63 compares the threshold with a reference voltage to output a result of the comparison. A fault detecting section 42 compares the respective outputs from the comparators 53 and 63 with each other to detect a characteristic shift of the threshold of each of the monitor circuits 50 and 60.

Abstract: Provided is a power management system capable of controlling charge and discharge of storage batteries according to power requirement of load even when handling electric power of large scale. A system controller receives load-related information data including the power requirement of load and storage battery-related information data including a state of a storage battery assembly including multiple storage batteries and creates an overall charge-discharge control instruction for the entire power management system based on the load-related information data and the storage battery-related information data. A hierarchical charge-discharge control apparatus receives the overall charge-discharge control instruction from the system controller and performs charge-discharge control of the multiple storage batteries, classified into hierarchical levels, on a hierarchical level basis.

Abstract: Embodiments of the present invention disclose a charging and discharging management apparatus and a mobile terminal. The charging and discharging management apparatus may include a charging and discharging management chip, primary battery positive and negative electrode contacts, secondary battery positive and negative electrode contacts, and electronic switches connected to the primary battery positive and negative electrode contacts and the secondary battery positive and negative electrode contacts, a detecting unit configured to detect in-place states of a primary battery and a secondary battery, and an electronic switch controlling unit connected to the detecting unit and configured to control the electronic switches to be on/off according to the in-place states of the batteries to enable the charging and discharging management chip to perform charging and discharging management for a battery in place.

Abstract: The disclosed embodiments provide a system that manages use of a battery pack in a portable electronic device. During operation, the system detects a characteristic of a battery bank in the battery pack that is associated with a gradual imbalance in the battery pack. Next, the system manages use of the battery pack based on the characteristic to prevent the gradual imbalance in the battery pack.

Abstract: Some embodiments relate to a power generation system. The power generation system includes a first generator and a first battery charger. The first battery charger is adapted to charge a first battery and a second battery. The first battery and the second battery are each adapted to provide power to start the first generator. The power generation system further includes a controller that determines a state of charge for each of the first battery and the second battery. Based on the state of charge for each of the first battery and the second battery, the controller determines which of the first battery and the second battery receives charging current from the first battery charger.

Abstract: A storage battery system includes: electric storage units; and DC-DC converters each provided between one of the electric storage units and a DC bus. Each of the DC-DC converters includes: a voltage sensor for detecting a voltage value at a connection point between the DC bus and the DC-DC converter; a second obtainment unit which obtains voltage values detected by the voltage sensors of the other DC-DC converters; and a control unit which, when a difference value between a statistic of the voltage values obtained by the second obtainment unit and the voltage value detected by the voltage sensor is not less than a predetermined threshold value, changes the voltage value detected by the voltage sensor, and controls an amount of charge in and an amount of discharge from a corresponding one of the electric storage units to approximate the changed voltage value to a predetermined target value.

Abstract: A battery charging method includes generating a plurality of charge profiles, each for a different one of a plurality of batteries, wherein a charge profile indicates a charge current as a function of charge time, and at least two of the charge profiles have a different charge current at a same charge time, and concurrently charging each of the plurality of batteries based on a corresponding charge profile.

Abstract: Systems and methods for in-vehicle charging of pallet jack batteries are provided. An example system allows using a power source of a host vehicle configured to provide power at voltage levels lower than the operating voltage of the pallet jack battery stack. The system may allow, for example, charging a 24 volts pallet jack battery stack from a 12 volts power source of the host vehicle. The system may further comprise an interconnecting circuit having a plurality of contactors electrically coupling the batteries in parallel for charging and serially for discharging. The system may further comprise a voltage monitoring circuit to detect whether the pallet jack is connected to the host vehicle power source for charging. Based on the detection, the voltage monitoring circuit may reconfigure the interconnecting circuit to electrically couple the pallet jack batteries in parallel.

Abstract: A rack server system and an operating method applicable thereto are provided. The rack server system includes a battery backup unit (BBU) and at least one server. The operating method includes: communicating the server and the BBU with each other; the BBU providing a status information and a previous self-discharging test information to the server for the server to judge a status of the BBU; and providing power from the BBU to the server and adjusting a loading of the server according to the status information of the BBU when an input power is interrupted.

Abstract: A hybrid battery and its charging/discharging method automatically charges/discharges batteries having different capacities. The hybrid battery includes a plurality of rechargeable batteries; switching elements which are electrically connected to the plurality of rechargeable batteries having high current paths for electrically connecting to one of the high current paths; and a hybrid battery protection circuit electrically connected to the plurality of rechargeable batteries and driven by power supplied by one of the plurality of rechargeable batteries, the hybrid battery protection circuit charging/discharging the plurality of rechargeable batteries in sequence by transmitting an on/off signal to the switching element.

Abstract: Provided are a control apparatus for a secondary battery and a control method for a secondary battery, which suppress decreases in released power and absorbed power. When a power storage device is requested to release power, a limit for power supply to a power consuming body is set relatively higher, and when the power storage device is requested to absorb power, the limit for power supply to the power consuming body is set relatively lower. When the power storage device is requested to release power, a command value PD for released power is calculated by adding supplied power PS to a requested value PE for released power. When the power storage device is requested to absorb power, a command value PC for charged power is calculated by subtracting the supplied power PS from a requested value PA for absorbed power.

Abstract: Methods and systems are presented for charging and/or discharging multiple parallel-connected battery packs in portable electronic devices, in which a charging or discharging current of a second battery pack is regulated based at least in part on a charging or discharging current of a first battery pack.

Abstract: A power source device supplies power to a host for charging a finite power source of the host. The power is supplied through an interface connecting the host device. The interface may be a Universal Serial Bus (USB) cable or another type of local connection cable.

Abstract: Method and device for controlling charging stations for electrical vehicles. In order to minimize peak power demands in at least two charging stations 10 combined into a group 12, actual charging parameters are exchanged 32 within the charging stations 10 within the group 12, a load prediction for the group 12 is created 34 depending on at least the actual charging parameters, and setpoint charging parameters for the charging stations 10 of the group 12 are determined 38 depending on the load prognosis.

Abstract: A terminal includes a first battery to supply power to the terminal if a power level of the first battery is above a first reference threshold, a second battery to supply power to the terminal if the power level of the first battery is below the first reference threshold, and a switch to connect at least one of the first battery and the second battery to power the terminal based on the power level of the first battery, in which the first battery is detachable from the terminal.

Abstract: Systems and methods for electric vehicle battery systems with replaceable parallel electric vehicle battery modules are described herein. The electric vehicle battery system includes a plurality of electric vehicle battery modules connected in parallel. Each electric vehicle battery module includes a battery. Each electric vehicle battery module can also include a balancing circuit in electrical communication with a current path from the battery to an electric vehicle battery module output node. Each electric vehicle battery module also may have a current sensor in electromagnetic communication with the current path between the battery and the balancing circuit. The current sensor can be configured to sense a current level between the battery and the balancing circuit. The balancing circuit can be configured to balance the current level sensed by the current sensor of each electric vehicle battery module.

Abstract: Even when current values of a current that flows to a plurality of cell modules connected in parallel are different, efficient charging is performed. A charge control device that controls a charging current to be supplied to a plurality of cell modules connected in parallel compares a maximum current value, selected from current values detected by a current sensor provided in each of a plurality of the cell modules, with a reference current value predetermined as a maximum current value of the current to be supplied to secondary batteries, and controls the charging current to be supplied to a plurality of the cell modules based on a comparison result.

Abstract: A power supply apparatus is provided that has a plurality of secondary batteries connected in series, outputs a composite voltage of all of the secondary batteries, and outputs an output of a part of the secondary batteries as a partial voltage. The power supply apparatus includes a detecting unit that detects states of the secondary batteries, a changing unit that changes an order of series connection of the plurality of secondary batteries based on a detection result of the detecting unit in such a manner that the partial voltage is outputted from a secondary battery that is in a relatively good state.

Abstract: An electric vehicle energy system is provided. The electrical vehicle energy system includes an electrical control unit used for producing the electric vehicle mode according to the external input signals. The electrical vehicle energy further includes an energy storage system used for producing a motor control signal according to an electric vehicle mode. The power loop structure includes at least a first power module and a second power module. The structure further includes at least a first detector and a second detector used for producing a first detecting signal and a second detecting signal according to the first power module and the second power module. The power loop structure further includes an energy storage controller used for producing the plurality of switch control signals according to the electric vehicle mode, the first detecting signal and the second detecting signal through a control area network by a voltage-difference hysteresis operation.

Abstract: A power storage system is provided with a battery and a battery charger which charges a battery pack having a battery voltage and current detection circuit. A charge circuit is structured such as to acquire terminal voltage information of the battery from a battery voltage detection circuit of the battery pack in a charging process, carry out a constant current charge control in a state in which the terminal voltage of the battery is equal to or lower than a previously determined reference voltage value of the battery, and switch to a constant voltage charge control maintaining the output voltage of the charge circuit in the case that the terminal voltage of the battery goes beyond the reference voltage value, thereby carrying on the charge until the battery is fully charged. Therefore, the power storage system can accurately charge the battery to a prescribed amount safely.

Abstract: A power storage system is provided with charge switches, discharge switches, a bidirectional DC/DC converter and a power storage system controller connecting all the battery packs to an external circuit to achieve parallel charge and discharge, and the power storage system starts the charge by setting a rated charge current value per one battery pack to Iset and setting the rated charge current value Iset as an initial value of a charge current command value Iref(1), thereafter monitor the charge current of each of the battery packs after elapse of a predetermined time so as to subtract its maximum value Ibmax(1) from the charge current command value Iref(1), and add the rated charge current value Iset to result of subtraction Ierr (Iref(1)?Ibmax(1)) so as to set as a new charge current command value Iref(2) and carry out pre-charge in such a manner as to carry on the charge.

Abstract: Energy storage system having one or more battery packs and a system controller for controlling the battery packs. Each battery pack has rechargeable storage cells and a battery pack controller in communication with the system controller. Through the operation of the system controller, battery packs with different initial charge states can be operated in parallel during the charge or discharge process. Discharging multiple battery packs in parallel offers not only higher capacity and longer run time than is available from a single battery pack, but also offers higher peak currents than available from a single battery pack, important in motor control applications. Battery pack design including a battery pack connector with both power and control contacts supporting user replacement of the battery packs.

Abstract: A power source apparatus mounted to a vehicle is equipped with a lead-acid battery and a lithium battery. An open circuit voltage and an internal resistance of each of the batteries are determined to satisfy the following conditions (a1), (a2), and (a3): (a1) In the use range of SOC of the lead-acid battery and the use range of SOC of the lithium battery, there is an equal voltage point Vds at which the open circuit voltage V0 (Pb) of the lead-acid battery becomes equal to the open circuit voltage V0 (Li) of the lithium battery; (a2) The relationship of V0 (Li)>V0 (Pb) is satisfied in the upper limit side of the use range of SOC of the battery; and (a3) A terminal voltage Vc (Li) of the lithium battery is not more than a set voltage Vreg of a regulator when a maximum current flows in the lithium battery.