Abstract: In one example, a photovoltaic module includes a plurality of discrete photovoltaic cells arranged in a plurality of cell rows, and a substantially electrically conductive and continuous area backsheet. The photovoltaic cells in each cell row are electrically connected in parallel to each other. The cell rows are electrically connected in series to each other and include a first row and a last row. The backsheet forms a current return path between the first and last rows. The photovoltaic cells are configured such that, in operation, current flows substantially uni-directionally through the plurality of photovoltaic cells between the first row and the last row.

Abstract: To provide a power control system which evaluates an applied control pattern over a period of a certain length or more, so as to be used for the subsequent control with a configuration in which a discharge start time and output of an electric storage device are changed.

Abstract: Method and system for load sharing in a multiple power supply system. At least some of the illustrative embodiments are power supply units including a switching circuit, a coarse adjustment circuit coupled to the switching circuit (the coarse adjustment circuit configured to send an internal command to the switching circuit to modify a pulse width modulated signal that controls output current of the power supply unit), and a communication port coupled to the switching circuit. The power supply unit configured to receive from an external device over the communication port an external command to modify the pulse width modulated signal of the switching circuit. The power supply unit is also configured to modify the output current, the amount of modification based on the external command, and the internal command from the coarse adjustment circuit.

Abstract: A power conversion system and method includes a DC-DC converter and an auxiliary circuit configured to ensure that a minimum input voltage is provided to the DC-DC converter during power interruption and for at least a predetermined hold-up time period. The auxiliary circuit includes an energy storage device, an auxiliary energy source for charging the energy storage device, and a clamping circuit to limit the energy stored by the energy storage device to a threshold voltage. A discharge time of the energy storage device from the threshold voltage to the minimum voltage thereby exceeds the predetermined hold-up time, but is only incrementally greater such that the size of the energy storage device is substantially reduced. The auxiliary energy source may typically be a current source, with the clamping circuit being control logic effective to disable the current source as a voltage across the storage device approaches the threshold.

Abstract: A system to energy being used from the electric grid as well as being used and generated from one or more energy generators or fuel-powered turbines, including, but not limited to, natural gas generators, fuel cells, diesel generators, bio-diesel generators, ethanol generators, propane generators, biogas generators and kerosene generators, or a combination of any or all of these sources, with or without a battery energy storage system, resulting in (a) a reduction of the peak power demand from the electric grid of a user of the system, and/or (b) a reduction of the high consumption charges during times in which consumption costs are higher due to variable billing or otherwise, and/or (c) the ability to provide energy to the user of the system at a time that such user is offsetting, in whole or in part, a reduction of its demand from the electric grid to, among other things, quality for, participate in and/or satisfy the requirements of demand response or similar programs with third parties.

Abstract: A current collection box includes: a number of terminals enabling the connecting of at least two solar cell strings including a plurality of solar cells are connected in series; a booster for boosting individual voltages of the generated power of each of the solar cell strings inputted via the terminals; and an output circuit for collecting all of the outputs of the booster together into a single output and then outputting the single output, wherein each of the boosters starts MPPT operation, which operates so that the output power of the solar cells is controlled so as to reach a maximum value, with different periods.

Abstract: A multiple-input power converter transferring energy from multiple input sources to a load comprises a plurality of voltage inputs. The power converter implements soft-switching techniques thereby reducing the converter switching losses and increasing the converter efficiency while using fewer components than presently designed multiple-input power converters. Such a power converter may include multiple input sources, where serially connected switches are coupled to one of the multiple input sources in an input leg. A voltage blocking capacitor is inserted between these input legs. Furthermore, the power converter includes a transformer for isolating the load from the multiple input sources, where the voltage blocking capacitor is connected to the primary winding of the transformer.

Abstract: A compressor monitoring system includes current and voltage monitors, current and voltage averaging modules, a control module, and a switch. The current monitor measures a current drawn by a motor of a compressor. The current averaging module generates first and second average current values based on the current measured by the current monitor. The voltage monitor measures a utility power voltage. The voltage averaging module generates first and second average voltage values based on the voltage measured by the voltage monitor. The control module selectively generates a fault signal when a first ratio is greater than a first predetermined threshold and a second ratio is less than a second predetermined threshold. The first ratio is based on the first and second average current values. The second ratio is based on the first and second average voltage values. The switch deactivates the motor when the fault signal is generated.

Abstract: A system and method for re-balancing power supply efficiency in a networking environment. Identification of changes in a network device that affect power consumption can be used to generate power request messages that are communicated to a power supply control via a communication bus. Based on such power request messages, the power supply control can then identify a re-balanced configuration of the power supply system to enable efficient operation of the power supply system.

Abstract: A drive circuit comprising a DC bus configured to supply power to a load, a first fuel cell coupled to the DC bus and configured to provide a first power output to the DC bus, and a second fuel cell coupled to the DC bus and configured to provide a second power output to the DC bus supplemental to the first fuel cell. The drive circuit further includes an energy storage device coupled to the DC bus and configured to receive energy from the DC bus when a combined output of the first and second fuel cells is greater than a power demand from a load, and provide energy to the DC bus when the combined output of the first and second fuel cells is less than the power demand from the load.

Abstract: A battery system includes a battery panel which includes a battery pack including a plurality of secondary battery cells, and a battery management unit to monitor at least one of a voltage, a temperature and a degradation level of the secondary battery cell; and a DC/DC conversion device. The DC/DC conversion device includes an interactive DC/DC converter which converts power discharged from the battery pack into a prescribed voltage to output converted power, and converts power supplied from outside into a prescribed voltage to output converted power; a control unit which controls the interactive DC/DC converter; a communication unit which communicates with the battery management unit and the control unit; a control source unit; and a battery connected to a power supply line of the control source unit through a switch.

Abstract: A household appliance (1) includes an electronic command device (3) configured to reduce standby-state energy consumption of the electric household appliance (1). The electronic command device (3) includes an electronic control unit (20) and a switching mode low power supply unit (6) with a switching regulator unit (13) having a first control terminal (11) and at least an output terminal (9) which supplies a main prefixed supply voltage (VB) to the electronic control unit (20). The switching mode low power supply unit (6) is further configured to switch from a standby state to an operating state, when a prefixed voltage variation (?V) on the first control terminal (11) is detected. The switching mode low power supply unit (6) includes auxiliary supply means (14) which supply a low supply voltage (V1) different than zero to the first control terminal (11) during at least the standby state.

Abstract: Power over Ethernet power sourcing device is provided inside a light fixture to enable a communications interface and provide electrical power to devices such as cameras, rain sensors, chemical sensors, wireless data uplink units, and other power over Ethernet powered devices. The power over Ethernet system is especially adapted for use in LED street lights and must be able to operate from a wide AC voltage supply range that is typically found in these types of lights.

Abstract: An inverter assembly having a DC circuit, inverter, and controller (CTRL) configured to control the inverter, the inverter being, for example, a multilevel inverter having a first half bridge (HB1) and a second half bridge (HB2). The controller (CTRL) can be adapted to provide a first operating state in which the controller (CTRL) operates the inverter as a full-bridge inverter. The controller (CTRL) is further adapted to provide at least one further operating state in which the controller (CTRL) operates the inverter as a half-bridge inverter, the controller (CTRL) being adapted to select an operating state based on predetermined conditions.

Abstract: The present disclosure provides an electric power supplying apparatus including: an electric storage device; and a control portion configured to control processing for mixing an output from the electric storage device, and an electric power of an external electric power system with each other in accordance with at least one of a peak shift command, a load electric power, and a remaining capacity of the electric storage device, wherein an alternating current electric power is formed in the mixing processing. When the electric power supplying apparatus further includes an electric power generating apparatus, processing for mixing an output from the electric power generating apparatus, an output from the electric storage device, and an electric power of the external electric power system with one another, is controlled.

Abstract: This disclosure provides systems, methods and apparatus for a combined battery/capacitor energy storage device. The device includes a first device terminal, a second device terminal, a battery connected between the first terminal and the second terminal, and a capacitor connected in parallel with the battery. In one aspect, a rectifier is connected between the first terminal and the capacitor, the rectifier configured to allow substantially unidirectional current flow from the first terminal to the capacitor. In another aspect, a switch is between the capacitor and the first terminal. In another aspect, a current limiter extends between the first terminal and the capacitor.

Abstract: A lamp base having an electrical device recharging receptacle configured to receive a plug from a recharging device for a portable rechargeable electronic device. The receptacle is configured as a standard automobile cigarette lighter receptacle. The receptacle includes standard cigarette lighter receptacle electrical contacts that are connected to a voltage and current conversion circuit for receiving standard household voltage and converting it into standard automotive voltage and current. An adapter receptacle is provided in the lamp base with securable replacement electrical and mechanical connection mechanism, wherein the conversion circuit provides a voltage and current to the adapter receptacle. A replaceably securable USB adapter plug comprising a second conversion circuit for converting the voltage and current provided to the adapter receptacle into a standard USB voltage and current.

Abstract: An exemplary powered device (PD) connected to a local power source and a power sourcing equipment (PSE) includes a constant current source drawing at least 10 mA direct current from the PSE when the local power source is in operation. The PD includes a first conversion circuit, a first diode, and a second diode. The first conversion circuit comprises a first input and is configured for converting a voltage input to the first input into the rated working voltage of the PD. The positive terminal of the first diode is connected to the local power source and the negative terminal thereof is connected to the first input. The voltage of the local power source is higher than that of the PSE.

Abstract: According to one embodiment, a filter circuit includes a first filter that includes two first capacitors connected in series, two single-phase AC reactors connected to one ends of the two first capacitors, respectively, a second capacitor connected at one end to a neutral point of the two first capacitors, and a third capacitor connected between another ends of the two single-phase AC reactors, and a second filter that includes two common mode chokes and two fourth capacitors connected in series between one ends of the two common mode chokes.

Abstract: A control circuit of a switching power supply device has a first current source capable of supplying an auxiliary current to a load resistance of the switching power supply device when a load current flowing through the load resistance increases, a second current source capable of pulling in a current from the load resistance when the load current flowing through the load resistance decreases, and an auxiliary current controller configured to activate the first current source or the second current source from when a variation in the load current flowing through the load resistance is detected to have exceeded a predetermined level until a current flowing through the inductor becomes equal to the current flowing through the load resistance.

Abstract: A current balance circuit includes a first and a second current sensors, an averager, a first and a second control modules, and a first and a second rheostat elements. The first and second current sensors receive a first current and a second current from a power source respectively and convert the first and second currents into a first and a second voltages. The averager receives the first and second voltages and calculates to obtain an average voltage. The first and second control modules receive the first voltage, the second voltage, and the average voltage, to obtain a first and a second control signals, to control current conduction ability of the first and second rheostat elements, to make the first and second currents keep a dynamic balance.

Abstract: A control unit of a system stabilization device uses a fluctuation detection block (60) to determine fluctuation components included in the active component and reactive component currents of a system current and fluctuation components included in the frequency signal and the amplitude signal of a system voltage. The high frequency cut-off of the fluctuation detection block (60) is set to be f1; the low frequency cut-off is set to be f2. The fluctuation detection block (60) is composed of a low-pass filter (61) with a time constant of T1, a low-pass filter (62) with a time constant of T2, a subtracter (63) which outputs the difference, between the output signals of the filter (61) and the filter (62), and a feedback circuit (64) which provides feedback on the output of the subtracter (63) to the filters (61, 62). Thus, stability is ensured without using a current detector.

Abstract: In certain embodiments, the present invention includes a system for generator set control comprising a controller and two or more power generators configured to supply power to an electrical load. The two or more power generators are coupled to the controller, where the controller is configured to synchronize the two or more power generators with one another. In some embodiments, the controller is configured to automatically shut off or turn on at least one of the two or more power generators in response to the electrical load to increase the overall power efficiency of the system. In further embodiments, the system is configured to operate in ambient temperature environments ranging from ?55° C. to +125° C. The controller can be a digital controller, analog controller, or a combination therewith. Furthermore, the system can be configured to operate in a micro-grid array.

Abstract: An internal power circuit lowers a battery voltage supplied always from an external side to generate a standby power voltage. A timer continues to measure an elapse of time in a standby state, after a main relay is turned off and supply of a power voltage is interrupted. A measured time data of the timer is saved to a save register during a time measurement operation of the timer. When a stop condition for stopping the time measurement operation of the timer is satisfied, a control circuit stops the operation of the internal power circuit. When the main relay is turned on, the internal power circuit is activated to start its operation again by the control circuit so that the measured time data saved to the save register is restored to the timer.

Abstract: An electronic device includes a central processing unit (CPU), a number of power supply units (PSUs), a north bridge, a south bridge, and a baseboard management controller (BMC). The number of power supply units (PSUs) supplies power to the CPU. Each PSU has a rated power. The north bridge is connected to the CPU. The south bridge is connected to the north bridge. The BMC is connected to the CPU by the north and south bridges. The BMC detects power supply states of each PSU and controls the north bridge to adjust a power consumption of the CPU according to the power supply states of the PSUs.

Abstract: A power management system which carries out charge-discharge control according to lack of storage cell pack characteristic uniformity. A power storage device comprises a power storage unit, a power system switching circuit, and a power management unit. The power management unit: acquires charge information (for example, charge rate SOC) on each of a plurality of storage cell packs contained in the power storage unit; compares the size of said charge information according to the minimum and maximum values thereof respectively with an upper bound and a lower bound, and switches a charge switch and a discharge switch of the power system switching circuit; and transitions the power storage unit between a charge-discharge state, a charge state, and a discharge state.

Abstract: Provided is a power management system, wherein charging/discharging is conducted while reliably preventing overcharging/over-discharging, and charging/discharging control of a storage-battery system comprising a plurality of storage battery units is conducted. An overall storage-battery-unit management unit detects voltages of storage-battery packs composing the storage-battery system, voltages of unit cells composing the storage-battery packs, and serial voltages of the storage battery units, each of which comprises a plurality of storage-battery packs connected in series. Charging is stopped when either of these voltages exceeds an upper limit value, and discharging is stopped when either of these voltages is less than a lower limit value.

Abstract: Conventional circuits often have undesirable characteristics to due “hot spots” or use a large amount of area. Here, however, a charging circuit is provides that uses an improved driver. Namely, an amplifier within a current sensor is used to control the rate that a switch can charge an external capacitor. This is accomplished through the adjustment of the gain of the amplifier during a charging mode.

Abstract: A current limited system for providing a burst current capability comprises a variable load having a first mode of operation requiring a first current level and a burst current mode of operation requiring a second current level. The second current level is greater than the first current level. A control processor provides control signals for the current limited system. A voltage source is connected to the variable load to provide a source current. The source current provides the variable load the first current level in the first mode of operation. A burst mode circuit provides the second current level to the variable load in the burst current mode of operation, responsive to the control signals from the control processor and the voltage source.

Abstract: A power generation system has a generator, a power bus and an electrical accumulator unit. The electrical accumulator unit includes an independent controller that actively filters transients from the power bus.

Abstract: Disclosed is a system and method for improving grid efficiency, reliability, security and capacity, utilizing energy storage over a plurality of on-site energy storing appliances, and also utilizing on-site demand reduction devices lacking storage, all controlled via configuration settings with a local means to act independently, yet in statistical coordination, to provide a desired effect. The appliance and controller are located on the downstream side of the end-users power meter, and facilitates the utilization of the stored energy and manages the optimal timing for producing and delivering the stored energy to the end-user. This model demonstrates a utility driven, disaggregated, distributed energy system, where the distributed energy resource is designed to behave as an offset to the predictable daily electrical demand profile.

Abstract: Methods and apparatus to control power in a printer are disclosed. An example apparatus includes a first field effect transistor having a first terminal, a second terminal, and a third terminal, the second terminal coupled with a first voltage input. The example apparatus further includes a second field effect transistor having a fourth terminal, a fifth terminal, and a sixth terminal, the fourth terminal coupled with the first terminal of the first field effect transistor, the fifth terminal coupled with a second voltage input. The example apparatus further includes a first comparator having a first input coupled to the first input voltage, having a second input coupled to the second input voltage, and having an output coupled with the third terminal.

Abstract: The present invention discloses a smart power supply system for electrical appliances, using a rechargeable power storage device, a logic controller, and a learning controller, to control and minimize electricity consumption from mains power during standby. In standby mode, when only a small amount of electrical power is needed, energy from the power storage device is used and mains power is disconnected unless the power storage device requires a recharge. A logic controller senses the appliance's operating state, using it to determine when power should be supplied from mains power or the power storage device. A learning controller monitors and stores historical characteristics of the power storage device's charge and discharge cycles, using them to automatically calculate new recharge cycle parameters to minimize mains power consumption. An external input and output module enable users, computers and electronic devices to interact and program the learning controller.

Abstract: The present invention relates to a power management system comprising at least one power management subsystem. Each power management subsystem comprises a first power module coupled to a first load and comprising at least one first power supply for supplying power to the first load; a second power module coupled to a second load and comprising at least one second power supply, wherein at least one second power supply is retractably installed in the second power module and selectively coupled to the second load; and a pass-through module comprising at least one pass-through unit retractably installed in the second power module to replace with the at least one second power supply and selectively connecting the first power module to the second load for allowing the first power module to supply power to the second load.

Abstract: [Problem] To provide an electricity supply system that efficiently utilizes electricity. [Solution] An electricity supply system includes: a power generation unit (10) for supplying electricity; a load unit (11) for consuming at least one of the electricity supplied from the power generation unit (10) and system electricity supplied from an electricity system; and a control unit (12) for controlling operations of the power generation unit (10) and the load unit (11). The power generation unit (10) supplies electricity to the electricity system, and the control unit (12) controls the power generation unit (10) and the load unit (11) on the basis of values of a plurality of types of electricity handled by the electricity supply system.

Abstract: The present invention relates to a multiple-input driving device, which receives at least one electrical power that shows a voltage. The multiple-input driving device uses interaction among a voltage regulation module, a control module, and a conversion module to simultaneously the functions of voltage regulation, input through pushbutton switch, driving a light-emitting diode with regulated power or driving the light-emitting diode with input of pulse width modulated power.

Abstract: An active low-pass current filter apparatus and method reduces conducted emissions above a predefined cutoff frequency at high power levels. The apparatus and method use a bidirectional DC-DC converter to minimize current fluctuations on a power lead that may result in conducted emissions above the predefined cutoff frequency. The bidirectional DC-DC converter absorbs current from the power lead and feeds current to the load lead as needed to compensate for the current fluctuations on the power lead. Power to the DC-DC converter is provided by a separate auxiliary power source. A monitoring circuit compares the voltage level of the auxiliary power source to a reference voltage and compensates for variations in the voltage level of the auxiliary power source without interfering with the suppression of the conducted emissions.

Abstract: An electronic device includes a power control circuit to generate a power mode signal and a plurality of voltage regulators to receive the power mode signal. Each voltage regulator reduces an output voltage in response to the power mode signal, and the reduced output voltage of each voltage regulator is used to power a different circuit of or function to be performed in the electronic device.

Abstract: A system and apparatus for generating power. In one embodiment, the apparatus comprises a power module for coupling to a DC power source via a DC bus, wherein the power module (i) converts a first power from the DC power source to a second power, and (ii) comprises a maximum power point tracking module unit for dynamically adjusting a load voltage of the DC power source; an AC bus; and a controller, physically separate from the power module and coupled to the power module via the AC bus, for operatively controlling the power module.

Abstract: A system and method of analyzing a powered device (PD) in a Power-over-Ethernet (PoE) system are presented. The system includes an Ethernet interface having a physical layer (PRY) chip capable of providing a signal pulse in addition to physical layer 1 functions. The system further includes a pulse transformer, coupled to the PRY chip, capable of relaying the signal pulse provided by the PRY chip to the PD via the transmit line and a second PRY chip. The first PRY chip receives one or more return pulse signals from the PD, analyzes characteristics such as voltage and/or frequency of the return pulse signal(s), and determines attributes of the PD based on those characteristics. The attributes can include powered device validity and power classification. A method of supplying power to a PD is also presented.

Abstract: A voltage drive circuit is constructed by stacking NMOS and PMOS transistors to provide high voltage levels with an output voltage swing greater than the breakdown voltage of the individual transistors used to build the voltage drive circuit. The voltage drive circuit may include a series stack of capacitors connected between gates of the stacked PMOS and NMOS transistors. The capacitive loading causes the gate signals to change more synchronously. Errors in timing for these gate signals, which would otherwise result in damage from exceeding the breakdown voltage across a pair of terminals of one of the NMOS and PMOS transistors, are mollified.

Abstract: An electrically powered device includes at least one electrically powered component and a power source having at least two cells. One cell powers the electrically powered component and the remaining cells are held in reserve. A control circuit is connected to the electrically powered component and the power source. The control circuit includes a controller which generates a charge signal, a boost regulator circuit connected to the controller which receives power from the power source and generates a boost signal for conversion into a charge signal. A capacitor is connected to the controller and receives the charge signal and provides a predetermined voltage to the electrically powered component. A boost regulator circuit and the controller monitor the power source and draw power from one of the remaining cells held in reserve when the cell is fully depleted.

Abstract: A photovoltaic power plant includes a photovoltaic inverter that converts direct current generated by solar cells to alternating current. The output of the photovoltaic inverter is provided to a point of interconnection to a power grid. A meter at the point of interconnection may be read to detect the output of the photovoltaic inverter at the power grid. The photovoltaic power plant includes a plant controller with a state machine. The plant controller is configured to adjust setpoints of the photovoltaic inverter to control the output of the photovoltaic power plant. The plant controller is also configured to soft start and soft stop automatic voltage regulation (AVR) of the photovoltaic power plant to prevent perturbing the AVR.

Abstract: A method for providing power to devices in a network and coordinating actions of multiple power supplies on the network is described. The method may include maintaining connectivity of communication signals and ground between upstream and downstream portions of the network relative to a power supply, while terminating power from an upstream power supply and taking over power supply functions for downstream devices. This may be achieved by including a logic feature within one or more of the multiple power supplies that monitors a power status of an upstream power supply and/or the power status of the associated power supply. When the logic feature detects a power cycle, it initiates a coordinated power cycle of the associated power supply and/or other networked power supplies.

Abstract: Circuits and methods for current limited DC-to-DC converters having multiple power sources have been disclosed. One of multiple power sources is activated by a multiplexer. A current sensing unit, deployed close to the multiplexer, detects if an input current to the DC-to-DC converter has reached a current limit. In case the current limit is reached a signal is sent to the DC-to-DC converter to reduce the current drawn the DC-to-DC converter.

Abstract: A plurality of modules each including at least a pair of series connected power MOSFETs are configured between a plurality of DC voltage sources, and a plurality output terminals for connection to respective loads, are controlled for selectively applying power to the loads via time delay switching incorporating forward biased intrinsic diodes of the MOSFETs in a given current path during initial application of power to a load, whereby a predetermined period of time after turning on one of the series connected MOSFETs, the associated other MOSFET is turned on to shunt its intrinsic diode for reducing the resistance in the current path to maximize current flow. The configuration of the plurality of power MOSFETs is also controlled for selectively providing bi-directional current flow between said plurality of DC voltage sources.

Abstract: A power supply selection/detection circuit to select one main power supply from a plurality of external power supplies includes a resistance element with one end connected to an external power supply and another end connected to the main power supply, a first voltage detector to receive a voltage of the external power supply and detect a voltage of the external power supply, a second voltage detector to detect a voltage between the ends of the resistance element, and a switch connected between the external power supply and a ground to short-circuit or open-circuit between the external power supply and the ground according to an output of the second voltage detector. The resistance element and the first voltage detector are disposed for each of the plurality of external power supplies, and the second voltage detector and the switch are disposed for at least one of the plurality of external power supplies.

Abstract: The invention relates to a redundant module for decoupling short-circuit currents in a redundant voltage supply. The redundant module comprises at least two power supply units, and the number of inputs corresponds at least to the number of power supply units. Each input is routed via a separate current path to a common current node of an output for providing an output current. Each current path forms a decoupling section, and at least one measuring element for measuring the input voltage, the input current, and/or the input power as well as a control element for regulation purposes are assigned to each decoupling section.

Abstract: A method for selecting an electric power supply and a circuit thereof are provided. The method includes detecting whether there is an output signal from a high electric power source, connecting a low electric power source with input of a transformer if there is no output signal from the high electric power source, disconnecting output of the transformer with a general circuit if there is no output signal from the high electric power source, transforming a voltage received from the low electric power source, and outputting the transformed voltage to a control unit. By disconnecting the output of the transformer with the general circuit, the low power source may reduce waste of an electric power.

Abstract: A battery load leveling system for an electrically powered system in which a battery is subject to intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the batteries. The system includes a passive storage device, a unidirectional conducting apparatus coupled in series electrical circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series electrical circuit coupled in parallel with the battery such that the passive storage device provides current to the load when the battery terminal voltage is less than voltage on the passive storage device, and a battery switching circuit that connects the first and second batteries in either a lower voltage parallel arrangement or a higher voltage series arrangement.