Charging and discharging control system for zinc air battery

Abstract

The invention discloses a charge and discharge control system for a zinc air battery. The charge and discharge control system comprises a plurality of electrochemical cells, a charge switch circuit and a discharge switch circuit. The charge switch circuit and the discharge switch circuit may be controlled to substantially isolate charging and discharging of the plurality of cells.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to USSN 63 / 715,308, filed November 1, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of zinc-air batteries, and more specifically to a charge-discharge configuration for zinc-air batteries. Background Technology

[0004] Zinc-air batteries have been known for over 100 years but have yet to be successfully commercialized. In a typical charging cycle, an electrolyte containing zinc hydroxide releases metallic zinc in the charging section, which then precipitates as a solid and accumulates in the discharging section. During discharge, the solid zinc is converted back into zinc hydroxide, releasing electrons in the process. The charge-discharge operation of zinc-air batteries can be controlled via separate terminals, which hinders other battery technologies from utilizing commercially available charge-discharge platforms. Summary of the Invention

[0005] Typically, an innovative aspect of the subject matter described herein can be implemented in an electrochemical cell system. The system may include a first cell and a second cell, each cell having a negative charging terminal and a positive charging terminal, as well as a negative discharging terminal and a positive discharging terminal. The electrochemical cell system may be adapted to discharge power into a current trap and to charge based on power from a current source, and may include a first discharge switching circuit operatively coupled to the positive discharging terminal of the first cell. The first discharge switching circuit may be operable to selectively supply current from the first cell to the current trap. The electrochemical cell system may include a second discharge switching circuit operatively coupled to the positive discharging terminal of the second cell and the negative discharging terminal of the first cell. The second discharge switching circuit may be operable to selectively supply current from the second cell to the current trap. The electrochemical cell system may include a controller configured to direct the operation of the first and second discharge circuits to substantially isolate the charging and discharging of the first and second cells. For example, the first and second discharge circuits may prevent the first and second cells from charging and discharging simultaneously.

[0006] The foregoing and other embodiments may each optionally include one or more of the following features, individually or in combination. In particular, one embodiment includes a combination of all of the following features.

[0007] In some embodiments, the electrochemical cell system may include a first charging switch circuit operatively coupled to a positive charging terminal of a first cell. The first charging switch circuit may be operable to selectively supply current from a current source to the positive charging terminal of the first cell. The electrochemical cell system may include a second charging switch circuit operatively coupled to a positive charging terminal of a second cell. The second charging switch circuit may be operable to selectively supply current from a current source to the positive charging terminal of the second cell, wherein the second charging switch circuit may receive current from the current source via at least one of the first cell and the first charging switch circuit.

[0008] In some embodiments, receiving the current output from the first battery cell into the second charging switch circuit may include receiving the current output from the current source via the negative charging terminal of the first battery cell, and wherein receiving the current output from the first charging switch circuit may include receiving the current output from the current source via at least one of a direct connection to the first charging switch circuit and an indirect connection to the first charging switch circuit at the positive charging terminal of the first battery cell.

[0009] In some embodiments, at least one of the first charging switch circuit and the second charging switch circuit may be operable to selectively bypass the positive charging terminal of the first cell from which current flows, thereby providing current from a current source to the second charging switch circuit.

[0010] In some embodiments, the first charging switch circuit can selectively bypass the positive charging terminal of the first battery cell by directing current to the negative charging terminal of the first battery cell connected to the second charging switch circuit.

[0011] In some embodiments, the second charging switch circuit can selectively bypass the current flowing into the positive charging terminal of the first battery cell by disconnecting from the negative charging terminal of the first battery cell and connecting to the positive charging terminal of the first battery cell.

[0012] In some embodiments, the controller may be operable to selectively discharge power from one or both of the first and second battery cells, and wherein the controller may be operable to selectively charge one or both of the first and second battery cells.

[0013] In some embodiments, the controller may be operable to control whether one or both of the first and second battery cells are discharging by selectively bypassing the first and second battery cells via operation of the first and second discharge switch circuits.

[0014] In some embodiments, the controller may be operable to control whether one or both of the first and second battery cells are being charged by selectively bypassing the first and second battery cells via operation of the first and second charging switch circuits.

[0015] In some embodiments, a first discharge switch circuit may be operable to selectively supply current from the first battery cell to a current trap via the positive discharge terminal of the first battery cell, and wherein a second discharge switch circuit may be operable to selectively supply current from the second battery cell to a current trap via the positive discharge terminal of the second battery cell.

[0016] In some embodiments, the current trap may be a boost converter operable to convert power from the electrochemical cell system to supply power to an external load.

[0017] In some embodiments, the current source may be a buck converter that is operable to convert external power to charge the electrochemical system.

[0018] In some embodiments, the first discharge switch circuit may be operable to selectively bypass current flow from the positive discharge terminal of the first cell by coupling the negative discharge terminal of the first cell to a current trap instead of coupling it to the positive discharge terminal of the first cell.

[0019] In some embodiments, the second discharge switch circuit may be operable to selectively bypass current flow from the positive discharge terminal of the first cell by disconnecting the negative discharge terminal of the first cell.

[0020] In some embodiments, the first charging switch circuit may include a first single-sided MOSFET having a first body diode configured to substantially block current flow from the positive charging terminal of the second cell to the negative charging terminal of the first cell.

[0021] In some embodiments, the sensor is coupled to a first single-sided MOSFET to provide an output that confirms the operation of the single-sided MOSFET to prevent conduction through the first body diode when charging the first cell.

[0022] In some embodiments, the structure of the first and second cells substantially restricts the flow of current through the first body diode from the negative charging terminal of the first cell to the positive charging terminal of the second cell.

[0023] In some embodiments, the first charging switch circuit may include a second single-sided MOSFET configured to selectively bypass charging of the first battery cell.

[0024] In some embodiments, the first charging switch circuit may include a first dual-sided MOSFET operable to selectively control the charging of the first battery cell.

[0025] Typically, an innovative aspect of the subject matter described herein can be implemented in a switching circuit for an electrochemical cell system comprising a first cell and a second cell, each including a negative charging terminal and a positive charging terminal, as well as a negative discharging terminal and a positive discharging terminal. The electrochemical cell system can be adapted to discharge power into a current trap and to charge based on power from a current source. The switching circuit may include a first MOSFET including a first body diode, wherein the first MOSFET may be connected between the negative charging terminal of the first cell and the positive charging terminal of the second cell. The first MOSFET may be operable to selectively control the charging of the first cell based on power from the current source, and the first body diode of the first MOSFET may be configured to substantially block the flow of current from the positive charging terminal of the second cell to the negative charging terminal of the first cell. The switching circuit may include a second MOSFET connected between the positive charging terminals of the first and second cells. The second MOSFET may be operable to selectively bypass the charging of the first cell.

[0026] The foregoing and other embodiments may each optionally include one or more of the following features, individually or in combination. In particular, one embodiment includes a combination of all of the following features.

[0027] In some embodiments, the sensor may be coupled to a first single-sided MOSFET to provide an output that confirms the operation of the single-sided MOSFET to prevent conduction through the first body diode when charging the first cell.

[0028] In some embodiments, the structure of the first and second cells can substantially restrict the flow of current through the first body diode from the negative charging terminal of the first cell to the positive charging terminal of the second cell.

[0029] In some embodiments, the electrochemical cell system includes at least one fuse, wherein the at least one fuse is configured to isolate at least one of the electrochemical cells from other electrochemical cells in the system.

[0030] Before detailing the embodiments of the present invention, it should be understood that the invention is not limited to the operational details and structural details and component arrangements set forth in the following description or illustrated in the accompanying drawings. The invention may be practiced in various other embodiments and may be practiced or performed in alternative ways not explicitly disclosed herein. Furthermore, it should be understood that the wording and terminology used herein are for illustrative purposes and should not be considered restrictive. The use of “comprising” and “including” and variations thereof is intended to cover items listed thereafter and their equivalents, and additional items and their equivalents. Further, enumeration may be used in the description of the various embodiments. Unless expressly stated otherwise, the use of enumeration should not be construed as limiting the invention to any particular order or number of components. Nor should the use of enumeration be construed as excluding from the scope of the invention any additional steps or components that may be combined with or incorporated into the steps or components of the enumeration. Any reference to an element of the claim as “at least one of X, Y, and Z” means individually including any one of X, Y, or Z, and any combination of X, Y, and Z, such as X, Y, Z; X, Y; X, Z; and Y, Z. Attached Figure Description

[0031] Figure 1 An electrochemical cell system according to one embodiment is shown.

[0032] Figure 2 An electrochemical cell system according to another embodiment is shown.

[0033] Figure 3 An electrochemical cell system according to yet another embodiment is shown.

[0034] Figure 4 A switching circuit according to one embodiment is shown.

[0035] Figure 5 A switching circuit according to one embodiment is shown.

[0036] Figure 6 An operating method according to one embodiment is shown.

[0037] Figure 7 An electrochemical cell in an electrochemical cell system including a fuse is shown. Detailed Implementation

[0038] Figure 1An electrochemical cell system according to one embodiment is illustrated and is generally represented by 100. The electrochemical cell system 100 in the illustrated embodiment includes a plurality of cells 10-1, 10-2, 10-3... 10-N, a charging switch circuit 101, and a discharging switch circuit 102. The charging switch circuit 101 and the discharging switch circuit 102 can be operatively coupled to a controller 160, which can direct the operation of the charging switch circuit 101 and the discharging switch circuit 102 according to one or more aspects described herein. For example, the controller 160 can direct the operation of the charging switch circuit 101 and the discharging switch circuit 102 to prevent simultaneous charging and discharging of the plurality of cells 10-1, 10-2, 10-3... 10-N. In the charging mode where the charging switch circuit 101 effectively charges multiple battery cells 10-1, 10-2, 10-3... 10-N, the multiple battery cells 10-1, 10-2, 10-3... 10-N can form a charging string. In the discharging mode where the discharging switch circuit 102 effectively discharges the multiple battery cells 10-1, 10-2, 10-3... 10-N, the multiple battery cells 10-1, 10-2, 10-3... 10-N can form a discharging string.

[0039] As described herein, the electrochemical cell system 100 may include zinc-air cells, or possibly other types of metal-air cells, and four terminals that can be connected to form a charging string or a discharging string, but not both simultaneously. The reliability of the battery system may not be perfect, and there is no default cell tolerance; failure of a single cell can cause the entire system to shut down. Furthermore, the performance and capacity of cells within a string are not entirely equal and lose state-of-charge balance over time. The impedance / voltage asymmetry of the cells 10⁻¹, 10⁻², 10⁻³...10⁻N in the electrochemical cell system 100 may be greater than that of other conventional cell types such as lithium-ion or lead-acid, thus limiting the applicability of existing chargers / inverters within their voltage and current ranges. Due to the limitations of zinc wiping during charging, zinc-air based cells may need to be charged above a minimum charging current limit. According to one embodiment, the charging switch circuit 101 and controller 160 can be operated to comply with these limitations of metal-air based cells (such as zinc-air based cells).

[0040] In the illustrated embodiment, each of the multiple cells 10-1, 10-2, 10-3, ... 10-N includes 1) a positive charging terminal and a positive discharging terminal that are separate from each other, and 2) a negative charging terminal and a negative discharging terminal that are separate from each other. On one hand, the charging switch circuit 101 can be operatively coupled to the positive and negative charging terminals of a plurality of cells 10-1, 10-2, 10-3... 10-N to selectively control the charging of one or more of the cells 10-1, 10-2, 10-3... 10-N. On the other hand, the discharging switch circuit 102 can be operatively coupled to the negative charging and negative discharging terminals of the plurality of cells 10-1, 10-2, 10-3... 10-N to selectively control the discharging of one or more of the cells 10-1, 10-2, 10-3... 10-N. In other words, the charging and discharging portions of the plurality of cells 10-1, 10-2, 10-3... 10-N can be physically separated from each portion having positive and negative terminals. Therefore, a zinc-air battery can use cells with four terminals. It should be noted that if the charging and discharging sections are connected simultaneously, one or more cells may experience adverse side reactions, which could potentially damage one or more cells.

[0041] In one embodiment, a string of four-terminal cells 10-1, 10-2, 10-3... 10-N with the aforementioned terminal connection limitations can be presented as a dual-terminal battery for an external inverter, charger, or solar charger. In one embodiment, a controller 160 (e.g., a string controller) of the electrochemical cell system 100 can coordinate the charging switch circuit 101 and the discharging switch circuit 102 (e.g., multiple solid-state switches (SSS) on each set of charging and discharging terminals of each cell) with respect to the current trap 150 and current source 140 (either of which can be a DC / DC converter) on each charging and discharging cell string. Solid-state switches can achieve faster switching times than mechanical switches, thus allowing use cases such as uninterruptible power supply (UPS) applications. As described herein, it should be understood that the switches configured in the charging switch circuit 101 and the discharging switch circuit 102 are not limited to solid-state switches, and any type of switch can be used. Furthermore, a wide variety of types of solid-state switches can be used in solid-state switch configurations, making this disclosure limited to any one type of solid-state switch. Furthermore, any combination of different types of switches can be used (e.g., allowing multiple types of switches to be configured in charging switch circuit 101 and / or discharging switch circuit 102). Alternatively, in a configuration where the output of current source 140 and the input of current sink 150 are not isolated, controller 160 can direct the operation of another switch (e.g., SSS) at the end of the charge / discharge string to isolate the charge / discharge ground loop, such as... Figure 2The switch shown is referred to as selection switch 230. The electrochemical cell system 100 allows each cell in the series of cells 10-1, 10-2, 10-3... 10-N to operate at a voltage range and terminal configuration compatible with existing power conversion equipment.

[0042] The multiple cells 10-1, 10-2, 10-3... 10-N in the illustrated embodiments can each correspond to an electrochemical cell in an electrochemical system provided together in the form of a zinc-air battery. Discharging the cells 10-1, 10-2, 10-3... 10-N can involve a reaction with oxygen in the air to form ions, which migrate into zinc and then form zincates, thereby releasing electrons and providing current to supply a load. Charging the cells 10-1, 10-2, 10-3... 10-N can involve the deposition of zinc to release oxygen from the discharge reaction products. It should be understood that the charging and / or discharging modes of the multiple cells 10-1, 10-2, 10-3 ... 10-N and cells 10-1, 10-2, 10-3 ... 10-N may differ depending on the application, and this disclosure is not limited to any particular charging and discharging structure or mode of cells 10-1, 10-2, 10-3 ... 10-N.

[0043] exist Figure 1 In the illustrated embodiment, multiple battery cells 10-1, 10-2, 10-3... 10-N can be coupled to a current source 140, such as a charger (e.g., a buck converter), which is operable to supply current or a subset of current to the multiple battery cells 10-1, 10-2, 10-3... 10-N for charging according to the state of the charging switch circuit 101. The multiple battery cells 10-1, 10-2, 10-3... 10-N can also be coupled to a current sink 150, such as a boost converter (e.g., a boost converter), which is operable to receive current or a subset of current from the multiple battery cells 10-1, 10-2, 10-3... 10-N for discharging according to the state of the discharge switch circuit 102.

[0044] The current source 140 may be a charging buck converter configured to allow up to a target current, configured by the controller 160, to flow into the charging string without causing the main bus (e.g., DC bus) to drop below a set threshold (e.g., 52.5V) by reducing the charging current to 0A when the main bus approaches a set threshold.

[0045] The current trap 150 can be a discharge boost converter configured to amplify the voltage of the discharge cells 10-1, 10-2, 10-3... 10-N in series to a target voltage at the main bus (e.g., 47V, 48VDC, 60VDC, 72VDC, 96VDC, and 120VDC), and can be implemented by the controller 160, provided that sufficient discharge string voltage is available.

[0046] According to one embodiment, a charging switch circuit 101 may include a plurality of switch circuits 110-1, 110-2, 110-3... 110-N. The switch circuits 110-1, 110-2, 110-3... 110-N may be selectively controlled by a controller 160 to selectively charge one or more of the plurality of battery cells 10-1, 10-2, 10-3... 10-N. In one embodiment, the charging of battery cells 10-1, 10-2, 10-3... 10-N may be based on the characteristics of each battery cell 10-1, 10-2, 10-3... 10-N, such as the state of charge of the battery cells 10-1, 10-2, 10-3... 10-N. For example, based on the characteristics, the charging current provided from the current source 140 can selectively bypass one or more of the cells 10-1, 10-2, 10-3... 10-N.

[0047] Switching circuits 110-1, 110-2, 110-3... 110-N may each include one or more switches in the form of solid-state switches (e.g., MOSFETs). The switches in switching circuits 110-1, 110-2, 110-3... 110-N can be operated according to instructions from controller 160. Alternatively or additionally, switching circuits 110-1, 110-2, 110-3... 110-N may include internal circuitry capable of selectively activating a bypass mode based on characteristics of the cells 10-1, 10-2, 10-3... 10-N, the characteristics of which can be sensed by the internal circuitry. Alternatively or concurrently, the switching circuits 110-1, 110-2, 110-3... 110-N may receive instructions from circuits other than controller 160 (such as the cell management board (CMB) described herein and associated with cells 10-1, 10-2, 10-3... 10-N) to selectively activate bypass modes based on the characteristics of cells 10-1, 10-2, 10-3... 10-N. For example, the cells themselves may include sensor circuitry operable to instruct the switching circuits to activate bypass modes.

[0048] Charging bypassing the 10-1, 10-2, 10-3... 10-N cells can be achieved in several ways. Figure 1 In the illustrated embodiment, a switch 110-1 can be selectively bypassed from cell 10-1. This switch is operatively coupled to both the positive and negative charging terminals of cell 10-1. Switching circuit 110-1 can be selectively controlled to direct current from current source 140 through cell 10-1, or to bypass cell 10-1. To direct current from current source 140 through cell 110-1, switching circuit 110-1 can be controlled to provide a current path that allows current from current source 140 to flow from the positive charging terminal to the negative charging terminal. To bypass cell 10-1, switching circuit 110-1 can be controlled to provide an alternative current path where the potential of the current is significantly reduced as it flows. For example, a selectable bypass switch of switching circuit 110-1 can be activated to provide a current path between the positive charging terminal of cell 10-1 and a downstream connection, such as the positive terminal of a second cell 10-2 or current source 140. To provide current between the positive and negative charging terminals of cell 10-1, a selective charging switch of switching circuit 110-1 can be activated while a selective bypass switch is deactivated to provide a current path from the positive charging terminal to the negative charging terminal and then to downstream connections (such as the positive charging terminal of cell 10-2 or current source 140). The charging and charging bypass modes of each of the multiple cells 10-1, 10-2, 10-3... 10-N can be selectively controlled by charging switching circuit 101 in a similar manner, wherein the corresponding switching circuits 110-1, 110-2, 110-3... 110-N can be controlled to selectively charge or bypass the associated cells 10-1, 10-2, 10-3... 10-N.

[0049] The electrochemical cell system 100 may include a sensor system 162 coupled to one or more components of the electrochemical cell system (such as the charging switch circuit 101) and operable to provide a sensor output indicating one or more characteristics related to each of the plurality of cells 10-1, 10-2, 10-3... 10-N. For example, this characteristic may correspond to the voltage and / or state of charge of a particular cell among the plurality of cells 10-1, 10-2, 10-3... 10-N. Sensor system 162 can acquire such sensor output for each of the plurality of battery cells 10-1, 10-2, 10-3... 10-N, and provide such sensor output to controller 160, which can then selectively determine, based on the sensor output, which of the plurality of battery cells 10-1, 10-2, 10-3... 10-N is charged with current from current source 140. Sensor system 162 may include multiple sensors individually associated with each of the plurality of battery cells 10-1, 10-2, 10-3... 10-N; for example, sensor system 162 may include sensor aspects of CMB as described herein.

[0050] Alternatively, or in lieu of one or more components coupled to the charging switch circuit 101, the sensor system 162 may be optionally coupled to the discharging switch circuit 102 and operable to provide a sensor output indicating one or more characteristics relating to each of the plurality of cells 10-1, 10-2, 10-3... 10-N. For example, this characteristic may correspond to the state of charge of the cells among the plurality of cells 10-1, 10-2, 10-3... 10-N. The controller 160 may obtain such sensor output from the sensor system 162 and selectively determine which of the plurality of cells 10-1, 10-2, 10-3... 10-N discharges to supply current to the current sink 150.

[0051] In one embodiment, the discharge switch circuit 102 may include a plurality of switch circuits 120-1, 120-2, 120-3... 120-N. The switch circuits 120-1, 120-2, 120-3... 120-N may be selectively controlled by the controller 160 to selectively discharge one or more of the plurality of cells 10-1, 10-2, 10-3... 10-N. In one embodiment, the cells 10-1, 10-2, 10-3... 10-N are discharged according to the characteristics of each cell, such as the state of charge of the cells 10-1, 10-2, 10-3... 10-N. For example, based on characteristics (e.g., state of charge or voltage), one or more of the cells 10-1, 10-2, 10-3... 10-N can be selectively bypassed with respect to the discharge current supplied toward the current sink 150. Similar to the control of the plurality of switching circuits 110-1, 110-2, 110-3... 110-N of the charging switching circuit 101, the controller can guide the operation of the plurality of switching circuits 120-1, 120-2, 120-3... 120-N of the discharging switching circuit 102 based on sensor outputs (such as state of charge) from the sensor system 162.

[0052] Discharging bypassing cells 10-1, 10-2, 10-3... 10-N can be achieved in several ways. Figure 1In the illustrated embodiment, a switching circuit 120-1 can selectively bypass the battery cell 10-1. This switching circuit is operatively coupled to the positive and negative discharge terminals of the battery cell 10-1. The switching circuit 120-1 can be selectively controlled to direct current from the battery cell 10-1 to the current sink 150, or to effectively bypass the current path between the positive and negative discharge terminals for the battery cell 10-1. To direct current from the battery cell 10-1 to the current sink 150, the switching circuit 120-1 can be controlled to provide a current path for the current generated from the battery cell 10-1 with respect to the positive and negative discharge terminals, to supply to the current sink 150. To bypass the battery cell 10-1, the switching circuit 120-1 can be controlled to provide an alternative current path so that the potential of the current is significantly reduced as the current flows. For example, the selectable bypass switch of switching circuit 120-1 can be activated to provide a current path between the positive discharge terminal of cell 10-1 and an upstream connection (such as the positive terminal of the second cell 10-2 or current trap 150). To provide current between the positive charging terminal and the negative charging terminal of cell 10-1, the selective discharge switch of switching circuit 120-1 can be activated while the selectable bypass switch is deactivated to provide a current discharge path from the positive discharge terminal to the negative discharge terminal and then to a downstream connection (such as another switching circuit 120 or current trap 150). The discharge and discharge bypass modes of each of the multiple cells 10-1, 10-2, 10-3... 10-N can be selectively controlled in a similar manner by the discharge switch circuit 101, wherein the corresponding switch circuits 120-1, 120-2, 120-3... 120-N can be controlled to selectively discharge or bypass the associated cells 10-1, 10-2, 10-3... 10-N.

[0053] Controller 160 may include electrical circuitry and components for performing the functions and algorithms described herein. Generally, controller 160 may include one or more microcontrollers, microprocessors, digital signal processors (DSPs), and / or other programmable electronic devices programmed to perform the functions described herein. Controller 160 may additionally or alternatively include other electronic components programmed to perform the functions described herein or to support the microcontrollers, microprocessors, and / or other electronic devices. These other electronic components include, but are not limited to, one or more field-programmable gate arrays (FPGAs), system-on-a-chip, volatile or non-volatile memories, discrete circuits, integrated circuits, application-specific integrated circuits (ASICs), and / or other hardware, software, or firmware. Such components may be physically configured in any suitable manner, such as by mounting such components to one or more circuit boards, or otherwise arranged, whether combined into a single unit or distributed across multiple units. Such components may be physically distributed in different locations within the system or an aspect thereof, or they may be located in a common location within the system or an aspect thereof. When physically distributed, components can communicate using any suitable serial or parallel communication protocol, such as, but not limited to, CAN, LIN, Vehicle Local Area Network (VAN), FireWire, I2C, RS-232, RS-485, Ethernet, LAN, WiFi, and Universal Serial Bus (USB).

[0054] Controller 160 can direct charging switch circuit 101 and discharging switch circuit 102, and optionally similar circuits. Figure 2 The selector switch 230 is switched to provide at least three additional functions in the electrochemical cell system 100: 1) these functions enable selective bypassing of cells 10⁻¹, 10⁻², 10⁻³, ..., 10⁻N during charging or discharging or during both charging and discharging to provide cell default fault tolerance to the string; 2) these functions allow adjustment of the string current for a given current output from the current source 140 (e.g., charger output power); and 3) these functions enable fine-tuning of the cells 10⁻¹, 10⁻², 10⁻³, ..., 10⁻N by selectively removing cells from the string to bring the maximum and minimum cell states of charge closer to the string average state of charge.

[0055] In one embodiment, controller 160 may be operable to detect the voltage drop on the main bus to which the electrochemical cell system 100 is coupled (e.g., if the sun sets or the power grid fails and the grid voltage drops below a threshold voltage, such as 48V). Controller 160 may be coupled to current source 140 and / or current sink 150 (e.g., via analog and / or digital electronics) to enable or disable their operation. For example, controller 160 may enable or disable a DC / DC buck converter / charger (e.g., current source 140) and / or a DC / DC boost converter (e.g., current sink 150). If the main bus voltage drops below the threshold voltage, as described herein, controller 160 can disconnect the charging string via charging switch circuit 101 and close the discharging string via discharging switch circuit 102, thereby allowing power to flow from multiple cells 10-1, 10-2, 10-3... 10-N through current trap 150 in the form of a DC / DC boost converter, which amplifies the discharging string voltage to support the main bus.

[0056] When the bus voltage is supported by a solar or AC charger to a voltage level sufficient for charging, the controller 160 can detect this voltage level threshold. In response, the controller 160 can wait until the voltage level stabilizes above the voltage level threshold, then disconnect the discharge string via the discharge switch circuit 102, close the charging string via the charging switch circuit 101, and activate the current source 140, which is in the form of a DC / DC buck converter / charger, to supply current to the charging string.

[0057] In one embodiment, controller 160 can measure the discharge string voltage, and if the string voltage is below a voltage threshold, controller 160 can send a message to an external device (such as a power conversion system) to connect the main bus to grid power or another power source (if available) to avoid system downtime.

[0058] In one embodiment, controller 160 may interface with an air pump (not shown) associated with the electrochemical cell system 100 via a communication network (such as a CAN bus). The air pump can deliver air to cells 10-1, 10-2, 10-3...10-N in the respective cell strings according to instructions from controller 160. For example, controller 160 may instruct the air pump to adjust its speed based on whether the string is charging, discharging, or idle. Controller 160 may determine the air pump speed based on the air demand of the cell string related to the discharge current. The higher the current, the greater the air demand. The required amount can be determined by the stoichiometry of the zinc oxidation reaction.

[0059] In one embodiment, controller 160 may communicate with sensor system 162 via a communication network, such as a CAN bus. On one hand, sensor system 162 may include multiple cell management boards (CMBs) capable of measuring the charging and discharging voltages of each cell 10-1, 10-2, 10-3...10-N, with each CMB disposed on the cell. Optionally, the CMB may be configured to also manage wiper and pump operations associated with the respective cells 10-1, 10-2, 10-3...10-N.

[0060] As described herein, controller 160 can also be coupled to an external power switch (e.g., a grid connection trigger) via a communication network (such as a CAN bus) to control the external power supply to the DC bus.

[0061] In one embodiment, as described herein, controller 160 may be directly wired to switching circuits 110, 120 of the respective charging switch circuit 101 and discharging switch circuit 102 to control their operation. Switching circuits 110, 120 may be provided in a daisy-chain configuration between cells 10-1, 10-2, 10-3... 10-N.

[0062] In one embodiment, the controller 160 may be configured to estimate the average state of charge (SOC) of the strings using one or both of the following methods: 1) counting the charge-ampere-hours (AHs) of cells 10⁻¹, 10⁻², 10⁻³, ..., 10⁻N entering and leaving the strings, using an efficiency coefficient combined with a time-based self-discharge parameter; and 2) counting the AHs of cells 10⁻¹, 10⁻², 10⁻³, ..., 10⁻N entering and leaving the strings. This SOC may be transmitted via a communication network, such as a CAN bus.

[0063] Optionally, the controller 160 may direct the operation of the charging switch circuit 101 and / or the discharging switch circuit 102 via a communication network (such as a CAN bus). For example, the controller 160 may direct the charging circuit 101 and / or the discharging switch circuit 102 to selectively bypass and / or not bypass one or more cells 10-1, 10-2, 10-3... 10-N.

[0064] The controller 160 can operate according to one or more operating modes, including minimum charging current for wiping mode, series resistance estimation / high resistance connection detection mode, and cell control-low voltage bypass mode.

[0065] For the minimum charging current used in wiping mode, if the available power does not allow the cell string to be charged above a set current threshold, the controller 160 may temporarily disable charging. If the charging current is below the threshold for a set time, the controller 160 may disable the charger for a set time before attempting to charge again.

[0066] For series resistance estimation / high resistance connection detection mode Figure 6 The operation method is illustrated and generally represented by 1000. In the illustrated embodiment, controller 160 can initialize and monitor the individual cell terminal voltages reported and transmitted via the CAN bus, and compare the sum of the individual cell terminal voltages with the discharge string voltage. Steps 1001, 1002, 1004, 1006, 1008. Cell voltages are reported from one or more CMBs of sensor system 162 via the CAN bus—however, the cell voltages can be obtained directly by controller 160. Combined with current measurements, controller 160 can estimate the resistance of all connections within the cell string. Steps 1010, 1012. When the estimated resistance is above a resistance threshold, controller 160 can disable the cell string as a self-protection mechanism. Step 1014.

[0067] In cell control - low-voltage bypass mode, sensor system 162 (e.g., via one or more CMBs) can measure the charging and discharging terminal voltages of each cell 10-1, 10-2, 10-3... 10-N. If sensor system 162 detects that the discharging terminal voltage of cell 10-1, 10-2, 10-3... 10-N is below its low-voltage cutoff (LVC), controller 160 can command discharge switch circuit 102 to bypass the corresponding cell 10-1, 10-2, 10-3... 10-N.

[0068] As described herein, controller 160 can guide the operation of charging switch circuit 101 and discharging switch circuit 102 based on one or more thresholds associated with the voltage of the main bus, enabling electrochemical cell system 100 to operate for supplying and receiving power from the main bus. The following is a table of various thresholds and associated operating modes of electrochemical cell system 100 according to one embodiment. It should be understood that the number of thresholds and operating modes may vary depending on the application.

[0069] Table 1

[0070]

[0071] MPPT can be provided when the bus voltage is maintained by a solar maximum power point tracking (MPPT) charger. This is not applicable in grid-connected applications; therefore, for the purposes of discussion, 58V and 52.5V are provided only for solar applications and not for grid-connected applications. Additionally, it should be noted that the voltages and examples provided in Table 1 are provided as non-limiting examples for the purposes of discussion. The identified voltages are provided as a response to the quality of voltage regulation in some existing solar equipment. Typically, the first voltage may be a point higher than the nominal bus voltage (48V in this case). The second voltage may be slightly lower than the first voltage, indicating the bus voltage below which cell charging is no longer required (possibly due to limited bus power). The third voltage may be the nominal bus voltage. The fourth voltage may be a bus voltage just below the nominal bus voltage. Controller 160 can be configured to charge or discharge in response to the bus voltage. If the bus voltage is greater than the nominal bus voltage, controller 160 can switch to charging mode.

[0072] In the table above and the discussion above, it should be noted that the terms "minimum voltage during charging" and "current source off" are used. These indicate that the system can determine the point at which it transitions from charging to discharging.

[0073] For the purposes of discussion, the switching circuit 110-1 according to one embodiment is shown in further detail in the figures together with the first battery cell 10-1 and the second battery cell 10-2. It should be understood that additional battery cells and / or switching circuit 110 may be present. Furthermore, for the purposes of discussion, in Figure 5 The illustrated structure lacks a discharge terminal and discharge switch circuit 102. The switch circuit 110-1 in the illustrated embodiment includes a selective bypass switch 111 and a selective charging switch 113, which can operate as discussed herein to selectively charge or bypass the cell 10-1 to charge it with current from current source 140. In one embodiment, the selective bypass switch 111 and selective charging switch 113 may correspond to MOSFETs (e.g., Si MOSFETs or GaN MOSFETs) including a body diode. The selective bypass switch 111 and selective charging switch 113 may be single-channel MOSFETs capable of selectively controlling current flow in one direction. Alternatively, the selective bypass switch 111 and selective charging switch 113 may each be a dual-channel MOSFET capable of selectively controlling current flow in both directions, at the cost of additional on-resistance compared to a single-channel structure.

[0074] exist Figure 5In the illustrated embodiment, the body diode of the selective charging switch 113 is provided with an anode and a cathode, which allow current to flow from the negative charging terminal of the first cell 10-1 to the positive charging terminal of the second cell 10-1. In other words, the body diode of the selective charging switch 113 can prevent current from flowing in reverse from the positive charging terminal of the second cell 10-2 to the negative charging terminal of the first cell 10-1. This prevention of reverse flow can prevent accidental discharge of the first cell 10-1 and / or the second cell 10-2 (e.g., when in discharge mode). In other words, due to the structure of the first cell 10-1 and the second cell 10-2 and the arrangement of the body diode of the selective charging switch 113, current flow through the discharge terminal can be substantially prevented during discharge mode. During charging mode, current can be prevented from flowing from the anode to the cathode of the body diode of the selective charging switch 113 by selectively activating the selective bypass switch 111 or activating the selective charging switch 113 to provide a path with lower resistance.

[0075] It shows Figure 5 The body diode arrangement of the selective charging switch 113 contrasts with that of the discharging switch circuit 120, and allows the charging switch circuit 110 to use a single-blocking MOSFET switch instead of a back-to-back switch. This effectively halves the MOSFET Rds (on). The depicted configuration prevents current from flowing through the bypass switch during series operation and also prevents reverse current loops during bypass mode via the series switch.

[0076] For discussion purposes, according to one embodiment, the first switching circuit 110-1' and the second switching circuit 110-2' together with the first battery cell 10-1 and the second battery cell 10-2 are... Figure 4 Further details are shown below. The switching circuit 110 of the charging switch circuit 101 can be replaced by a first switching circuit 110-1' and a second switching circuit 110-2'. Figure 4 The image further details each of the first battery cell 10-1 and the second battery cell 10-2, each battery cell including a plurality of positive charging terminals and a plurality of negative charging terminals respectively associated with the positive and negative electrodes of the battery cell. Figure 1 In this configuration, for each of cells 10-1 and 10-2, multiple positive charging terminals and multiple negative charging terminals are connected together to provide both positive and negative charging terminals. However, in Figure 4In this circuit, the negative charging terminal of each of the cells 10-1 and 10-2 can be individually and respectively connected to one of a plurality of selective charging switches 113' of the first switches 110-1' and 110-2'. Control of the activation / deactivation of the selective charging switch 113' can be achieved by guiding current from the current source 140 through a selected pair (or more pairs) of negative and positive electrodes of the cells 10-1 and 10-2 to selectively charge one or more electrodes of the cells 10-1 and 10-2. The first switching circuit 110-1' and the second switching circuit 110-2' may include a selective bypass switch 111' similar to a selective bypass switch 111, and can be activated to bypass one of the cells 10-1 and 10-2, thereby preventing charging of the bypassed cells 10-1 and 10-2.

[0077] Go to Figure 2 An electrochemical cell system according to one embodiment is illustrated and is generally represented by 200. Electrochemical cell system 200 is similar to electrochemical cell system 100 in several respects but differs in others. For example, electrochemical cell system 200 includes a plurality of cells 10-1, 10-2, 10-3 constructed in the same manner as the cells discussed herein in conjunction with electrochemical cell system 100. Similarly, electrochemical cell system 200 includes a current source 140 and a current trap 150 constructed in the same manner as electrochemical cell system 100.

[0078] In the illustrated embodiment, the electrochemical cell system 200 includes a charging switch circuit 201 and a discharging switch circuit 202, which are operatively coupled to a controller 260. This controller may be similar to controller 160 and capable of directing the operation of the charging switch circuit 201 and the discharging switch circuit 202 according to one or more aspects described herein. For example, similar to controller 160, controller 260 may direct the operation of the charging switch circuit 201 and the discharging switch circuit 202 to prevent simultaneous charging of multiple cells 10-1, 10-2... 10-N.

[0079] On the one hand, the charging switch circuit 201 can be operably coupled to the positive charging terminal and negative charging terminal of a plurality of cells 10-1, 10-2... 10-N to selectively control the charging of one or more cells among the plurality of cells 10-1, 10-2... 10-N, while the discharging switch circuit 202 can be operably coupled to the negative charging terminal and negative discharging terminal of a plurality of cells 10-1, 10-2... 10-N to selectively control the discharging of one or more cells among the plurality of cells 10-1, 10-2... 10-N.

[0080] According to one embodiment, a charging switch circuit 201 may include a plurality of switch circuits 210-1, 210-2, ..., 210-N. The switch circuits 210-1, 210-2, ..., 210-N may be selectively controlled by a controller 260 to selectively charge one or more of the plurality of battery cells 10-1, 10-2, ..., 10-N. In one embodiment, the charging of battery cells 10-1, 10-2, ..., 10-N may be based on the characteristics of each of the battery cells 10-1, 10-2, ..., 10-N, such as the state of charge of the battery cells 10-1, 10-2, ..., 10-N. For example, based on these characteristics, the charging current supplied from the current source 140 may be selectively bypassed from one or more of the battery cells 10-1, 10-2, ..., 10-N.

[0081] Bypassing the cells 10⁻¹, 10⁻², 10⁻³... 10⁻N in the electrochemical cell system 200 can be achieved in a different manner than in the electrochemical cell system 100. For example, in... Figure 2 In the illustrated embodiment, a switching circuit 210-1 can selectively bypass the battery cell 10-1. This switching circuit is operatively coupled to both the positive and negative charging terminals of the battery cell 10-1. Similar to switch 110-1, the switching circuit 210-1 can be selectively controlled to direct current from current source 140 through the battery cell 10-1, or to allow such current to bypass the battery cell 10-1. To direct current from current source 140 through the battery cell 10-1, the switching circuit 210-1 can be controlled to provide a current path that allows current from current source 140 to flow from the positive charging terminal to the negative charging terminal. To bypass the battery cell 10-1, the switching circuit 210-1 can be controlled to provide an alternative current path such that the potential of the current is significantly reduced as it flows. For example, the selectable bypass switch of switching circuit 210-1 can be activated to bypass the positive charging terminal of cell 10-1 and direct current from current source 140 to downstream connections (such as another switching circuit 210 of charging switching circuit 201). The positive charging terminal of cell 10-1 can be bypassed by directing current from current source 140 to the negative charging terminal of cell 10-1, so that this current does not flow between the positive and negative charging terminals of cell 10-1.

[0082] To provide current between the positive and negative charging terminals of cell 10-1, a selective charging switch of switching circuit 210-1 can be activated while a selective bypass switch is deactivated to provide a current path from the positive charging terminal to the negative charging terminal and then to downstream connections (such as another switching circuit 210 of charging switching circuit 201). The charging and charging bypass modes of each of the multiple cells 10-1, 10-2... 10-N can be selectively controlled by charging switching circuit 101 in a similar manner, wherein the corresponding switching circuits 210-1, 210-2... 210-N can be controlled to selectively charge or bypass the associated cells 10-1, 10-2, 10-3... 10-N.

[0083] In one embodiment, the discharge switch circuit 202 may include a plurality of switch circuits 220-1, 220-2, ... 120-N. The switch circuits 220-1, 220-2, ... 120-N may be selectively controlled by the controller 260 to selectively discharge one or more of the plurality of cells 10-1, 10-2, ... 10-N. In one embodiment, the cells 10-1, 10-2, ... 10-N may be discharged based on the characteristics of each cell, such as the state of charge of the cells 10-1, 10-2, 10-3, ... 10-N.

[0084] For example, based on its characteristics, the discharge current supplied toward the current sink 150 can selectively bypass one or more of the cells 10-1, 10-2... 10-N. Similarly, the controller 260 can guide the operation of the multiple switching circuits 210-1, 210-2... 210-N of the charging switching circuit 201 based on sensor outputs (such as state of charge) from the sensor system 162.

[0085] Discharging bypassing cells 10-1, 10-2... 10-N can be achieved in several ways as described in this article. Figure 2In the illustrated embodiment, a switching circuit 220-1 can selectively bypass the battery cell 10-1. This switching circuit is operatively coupled to the positive and negative discharge terminals of the battery cell 10-1. The switching circuit 220-1 can be selectively controlled to direct current from the battery cell 10-1 to the current sink 150, or to effectively bypass the current path between the positive and negative discharge terminals for the battery cell 10-1. To direct current from the battery cell 10-1 to the current sink 150, the switching circuit 220-1 can be controlled to provide a current path for the current generated from the battery cell 10-1 with respect to the positive and negative discharge terminals, to supply to the current sink 150. To bypass the battery cell 10-1, the switching circuit 220-1 can be controlled to provide an alternative current path so that the potential of the current is significantly reduced as the current flows. For example, the selectable bypass switch of switching circuit 220-1 can be activated to provide a current path between the negative discharge terminal of cell 10-1 and an upstream connection (such as the negative discharge terminal of a downstream cell or current trap 150). To obtain current between the positive and negative charging terminals of cell 10-1, the selective discharge switch of switching circuit 120-1 can be activated while the selectable bypass switch is deactivated to provide a current discharge path from the positive discharge terminal to the negative discharge terminal and then to a downstream connection (such as another cell 10-1, 10-2... 10-N or current trap 150). The discharge and discharge bypass modes of each of the multiple cells 10-1, 10-2... 10-N can be selectively controlled in a similar manner by the discharge switch circuit 101, wherein the corresponding switch circuits 220-1, 220-2... 220-N can be controlled to selectively discharge or bypass the associated cells 10-1, 10-2... 10-N.

[0086] Similar to sensor system 162 and electrochemical cell system 100, electrochemical cell system 200 may include sensor system 262 coupled to one or more of its components (such as charging switch circuit 201) and operable to provide sensor outputs indicating characteristics (or characteristics) related to each of the plurality of cells 10-1, 10-2... 10-N. For example, a characteristic may correspond to the state of charge of a particular cell among the plurality of cells 10-1, 10-2... 10-N. Sensor system 262 may obtain such sensor outputs for each of the plurality of cells 10-1, 10-2... 10-N and provide such sensor outputs to controller 160, which may then selectively determine, based on the sensor outputs, which cell among the plurality of cells 10-1, 10-2... 10-N is charged with current from current source 140. Alternatively or concurrently, the controller 160 may selectively determine, based on the sensor output, which of the plurality of cells 10-1, 10-2 ... 10-N discharges into the current trap 150.

[0087] In the illustrated embodiment, the electrochemical cell system 200 includes a selection switch 230 operable to selectively couple either a charging switch circuit 201 or a discharging switch circuit 202 to ground and a corresponding one of a current source 140 and a current sink 150, depending on the operating mode (i.e., charging mode or discharging mode). The selection switch 230 may correspond to... Figure 2 The grounding interruptor described in the diagram, used in a "positive switch" configuration, operates because the two negative terminals are at different potentials. If the two negative terminals of cell 10-N are not isolated from the main bus, current will flow between them.

[0088] Figure 3 Alternative embodiments of the electrochemical cell system are illustrated and generally represented by 300. Electrochemical cell system 300 is similar to electrochemical cell system 100 in several respects but differs in others. For example, electrochemical cell system 300 includes a plurality of cells 10⁻¹, 10⁻², 10⁻³... 10⁻N constructed in the same manner as the cells discussed herein in conjunction with electrochemical cell system 100. Similarly, electrochemical cell system 200 includes a current source 140 and a current trap 150 constructed in the same manner as electrochemical cell system 100. Electrochemical cell system 300 may include a sensor system (not shown) similar to sensor system 162 described herein.

[0089] Unlike the electrochemical cell system 100, the electrochemical cell system 300 controls the charging and discharging modes of the system via a discharge switch circuit 302 (e.g., no charge switch circuit). A controller 360, similar to controller 160, can be provided to control the charging and discharging of the electrochemical cell system 300. The positive and negative charging terminals of multiple cells 10-1, 10-2, 10-3... 10-N can be connected to allow all cells to be charged via current from current source 140. During the charging mode when the current source 140 supplies current to multiple cells 10-1, 10-2, 10-3... 10-N, the controller 360 can instruct the discharge switch circuit 302 to activate multiple switch circuits 302-1, 320-2, 320-3... 320-N to disconnect the discharge path of each of the multiple cells 10-1, 10-2, 10-3... 10-N, thereby preventing the multiple cells 10-1, 10-2, 10-3... 10-N from charging and discharging simultaneously. In discharge mode, the multiple switching circuits 320-1, 320-2, 320-3 ... 320-N of the discharge switching circuit 302 can be activated by the controller 360 to provide circuit paths through the positive and negative discharge terminals of the multiple cells 10-1, 10-2, 10-3 ... 10-N and the current trap 150.

[0090] The operation of electrochemical system 300 can be similar to that of electrochemical system 100, except for the operation of the charging switch circuit. Conversely, as discussed, the discharging switch circuit 302 can be configured and controlled such that the discharging section and the charging section or series are not connected simultaneously, and such that adverse side reactions of one or more cells can be avoided.

[0091] MOSFETs typically cannot turn on when not powered, which is safer. However, there is a possibility that an SSS board might fail to close, potentially leading to uncontrolled discharge and even a fire. Furthermore, control logic errors causing erroneous relay commands can also cause this problem. While a thorough code review can uncover logic errors that might be causing this issue, electrical faults from any cause can also lead to it, which may go undetected. To prevent uncontrolled discharge, one of the switching sides needs to disconnect under normal conditions in the event of a fault and / or an integrated fuse can be provided to prevent overcurrent situations. Figure 7As shown, the electrochemical cell system may be equipped with a fuse F (e.g., a 60A fuse) between the positive terminal and the bypass switch, which is connected in series with the bypass switch. The fuse F may be added to the board or connected in series with the board on the bypass side. The fuse F may be inserted into the board, on the cable, or in another location. The fuse F may be added in series with the wires on each branch of the busbar attached to the air cathode. The location of the fuse F on the bypass side is preferred but not necessary because there is resistive loss through the fuse F, and the bypass switch is used less frequently, so the discharge current will not continuously flow through the fuse F and cause resistive loss. The fuse F is preferably a fast-acting fuse. Preferably, the voltage interrupted by the fuse F is less than 1.5V. One signal that the fuse F has tripped is that the discharge voltage of the cell cannot be measured, which should issue an alarm that the cell must be replaced.

[0092] Directional terms, such as “vertical,” “horizontal,” “top,” “bottom,” “up,” “down,” “inside,” “inward,” “outside,” and “outward,” are used to aid in describing the invention based on the orientation of the embodiments shown in the figures. The use of directional terms should not be construed as limiting the invention to any particular orientation.

[0093] The above description is a description of the current embodiments of the invention. Various changes and variations may be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, and these will be interpreted in accordance with the principles of patent law, including the doctrine of equivalents. This disclosure is presented for illustrative purposes and should not be construed as an exhaustive description of all embodiments of the invention or as limiting the scope of the claims to specific elements illustrated or described in connection with these embodiments. For example, but not limitingly, any individual element of the invention described may be replaced by an alternative element that provides substantially similar functionality or adequate operation. This includes, for example, alternative elements currently known, such as those currently known to those skilled in the art, and alternative elements that may be developed in the future, such as those that those skilled in the art may recognize as alternative elements during development. Furthermore, the disclosed embodiments include a set of features that are consistently described and can collaboratively provide benefits. The invention is not limited to those embodiments that include all of these features or provide all of the stated benefits, except to the extent expressly set forth in the published claims. Any reference to a claim element in the singular form, such as the use of the articles “a / an,” “the,” or “said,” should not be construed as limiting the element to the singular.

Claims

1. An electrochemical battery cell system, the system comprising: A first battery cell and a second battery cell, each including a negative charging terminal and a positive charging terminal, as well as a negative discharging terminal and a positive discharging terminal, the electrochemical battery cell system being adapted to discharge electricity into a current trap and charge based on electricity from a current source; A first discharge switch circuit is operatively coupled to the positive discharge terminal of the first cell, and is operable to selectively supply current from the first cell to the current trap. A second discharge switch circuit is operatively coupled to the positive discharge terminal of the second cell and the negative discharge terminal of the first cell, and is operatively operable to selectively supply current from the second cell to the current trap. as well as A controller configured to direct the operation of the first discharge switch circuit and the second discharge switch circuit to substantially isolate the charging and discharging of the first cell and the second cell.

2. The electrochemical cell system as described in claim 1, comprising: A first charging switch circuit is operatively coupled to the positive charging terminal of the first battery cell, and the first charging switch circuit is operable to selectively provide current output from the current source to the positive charging terminal of the first battery cell. as well as A second charging switch circuit is operatively coupled to the positive charging terminal of the second battery cell. The second charging switch circuit is operable to selectively provide current output from the current source to the positive charging terminal of the second battery cell. The second charging switch circuit receives the current output from the current source via at least one of the first battery cell and the first charging switch circuit.

3. The electrochemical cell system as described in claim 2, wherein, Receiving the current output from the first battery cell into the second charging switch circuit includes receiving the current output from the current source via the negative charging terminal of the first battery cell, wherein receiving the current output from the first charging switch circuit includes receiving the current output from the current source via at least one of a direct connection to the first charging switch circuit and an indirect connection to the first charging switch circuit at the positive charging terminal of the first battery cell.

4. The electrochemical cell system as described in claim 2, wherein, At least one of the first charging switch circuit and the second charging switch circuit is operable to selectively bypass the positive charging terminal of the first cell from which current flows, thereby providing current from the current source to the second charging switch circuit.

5. The electrochemical cell system as described in claim 4, wherein: The first charging switch circuit selectively bypasses the positive charging terminal of the first battery cell by directing current to the node of the first battery cell connected to the negative charging terminal of the first battery cell and the second charging switch circuit. or, The second charging switch circuit selectively bypasses the flow of current into the positive charging terminal of the first battery cell by disconnecting from the negative charging terminal of the first battery cell and connecting to the positive charging terminal of the first battery cell.

6. The electrochemical cell system as described in claim 2, wherein, The controller is operable to selectively discharge power from one or both of the first cell and the second cell, and wherein the controller is operable to selectively charge one or both of the first cell and the second cell.

7. The electrochemical cell system as described in claim 6, wherein, The controller is operable to: The discharge of one or both of the first and second battery cells can be controlled by selectively bypassing the operation of the first and second discharge switch circuits; or, The charging of one or both of the first and second battery cells is controlled by selectively bypassing the operation of the first and second charging switch circuits.

8. The electrochemical cell system as described in claim 1, wherein, The first discharge switch circuit is operable to selectively supply current from the first cell to the current trap via the positive discharge terminal of the first cell, and wherein the second discharge switch circuit is operable to selectively supply current from the second cell to the current trap via the positive discharge terminal of the second cell.

9. The electrochemical cell system as described in claim 1, wherein, The current trap is a boost converter, which is operable to convert power from the electrochemical cell system to supply power to an external load.

10. The electrochemical cell system as claimed in claim 1, wherein, The current source is a buck converter, which is operable to convert external power to charge the electrochemical system.

11. The electrochemical cell system as claimed in claim 1, wherein, The first discharge switch circuit is operable to selectively bypass current flow from the positive discharge terminal of the first cell by coupling the negative discharge terminal of the first cell to the current trap instead of coupling it to the positive discharge terminal of the first cell.

12. The electrochemical cell system as described in claim 1, wherein, The second discharge switch circuit is operable to selectively bypass the current flow from the positive discharge terminal of the first battery cell by disconnecting the negative discharge terminal of the first battery cell.

13. The electrochemical cell system as described in claim 2, wherein, The first charging switch circuit includes a first single-sided MOSFET having a first body diode configured to substantially block current flow from the positive charging terminal of the second cell to the negative charging terminal of the first cell.

14. The electrochemical cell system of claim 13, wherein, The sensor is coupled to the first single-sided MOSFET to provide an output that confirms the operation of the first single-sided MOSFET to prevent conduction through the first body diode when charging the first cell.

15. The electrochemical cell system of claim 13, wherein, The structure of the first battery cell and the second battery cell essentially restricts the flow of current through the first body diode from the negative charging terminal of the first battery cell to the positive charging terminal of the second battery cell.

16. The electrochemical cell system of claim 13, wherein, The first charging switch circuit includes a second single-sided MOSFET configured to selectively bypass charging of the first battery cell.

17. The electrochemical cell system of claim 13, wherein, The first charging switch circuit includes a first dual-sided MOSFET operable to selectively control the charging of the first battery cell.

18. A switching circuit for an electrochemical cell system, the electrochemical cell system comprising a first cell and a second cell, each of the first cell and the second cell comprising a negative charging terminal and a positive charging terminal, and a negative discharging terminal and a positive discharging terminal, the electrochemical cell system being adapted to discharge power into a current trap and to charge based on power from a current source, the switching circuit comprising: A first MOSFET, the first MOSFET including a first body diode, the first MOSFET being connected between the negative charging terminal of the first battery cell and the positive charging terminal of the second battery cell, the first MOSFET being operable to selectively control the charging of the first battery cell based on power from the current source, the first body diode of the first MOSFET being configured to substantially block the flow of current from the positive charging terminal of the second battery cell to the negative charging terminal of the first battery cell. as well as A second MOSFET is connected between the positive charging terminal of the first battery cell and the positive charging terminal of the second battery cell, and the second MOSFET is operable to selectively bypass charging of the first battery cell.

19. The switching circuit according to claim 18, wherein, The sensor is coupled to the first MOSFET to provide an output that confirms the operation of the first MOSFET to prevent conduction through the first body diode when charging the first cell.

20. The switching circuit as claimed in claim 18, wherein, The structure of the first battery cell and the second battery cell essentially restricts the flow of current through the first body diode from the negative charging terminal of the first battery cell to the positive charging terminal of the second battery cell.

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