Patent Publication Number: US-2022231516-A1

Title: Reconfigurable battery system for efficient charging and discharging

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present invention claims priority to U.S. Provisional Patent Application Ser. No. 63/139,271, filed Jan. 19, 2021, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Technical Field 
     The field of the present disclosure relates generally to battery systems, and more specifically, efficient battery systems. 
     Prior Art 
     Electric vehicles such as electric automobiles, trucks, marine vehicles, and aircraft are becoming more common in present society. All of these vehicles include batteries that need fast charging times that are comparable to the re-fueling process times of petroleum-based vehicles. Unfortunately, the rate of charge of batteries is primarily limited by the charge transportion process and the chemical reaction process (i.e., oxidation-reduction) within the battery. Fast charging exceeding this limit results in reduced charging capacity with potentially excessive heat generation that may cause thermal degradation of the battery. 
     In addition, as batteries discharge, their battery voltages decrease. Near the end of a battery&#39;s discharge capacity, the battery voltage can be as low as 40% of its voltage at a fully charged state. At this lower voltage, the battery current becomes large under a constant power load. This increased current produces significantly more heat at the battery, and at any equipment electrically connected to the battery, as compared to the heat produced when the battery voltage is higher and near the fully charged state of the battery. The adverse effects of this increased heat production include, for example, loss of energy (lower efficiency), increased system cooling load (consuming more power), increased equipment current ratings (heavier), and accelerated equipment degradation (short cycle life). As such, there is a need for a system and method that address these problems. 
     SUMMARY 
     A reconfigurable battery system is disclosed. The reconfigurable battery system comprises a battery cell array and a bus switch. The battery cell array configured to operate in a first discharge mode, a second discharge mode, and a charge mode. The battery cell array includes a plurality of battery cells arranged as at least a first column of battery cells between a second battery terminal and a first battery terminal and a switch between each battery cell within the first column of battery cells. The bus switch in signal communication with the battery cell array at the first battery terminal and is configured to select between electrically connecting the first battery terminal to a normal voltage bus or a high-voltage bus. The battery cell array may also include a plurality of battery cells arranged as a plurality of columns of battery cells between the second battery terminal and the first battery terminal and the switch may be between each battery cell within each column of the plurality of columns of battery cells. 
     In an example of operation, the reconfigurable battery system may perform a method that comprises electrically connecting the first battery terminal to the normal voltage bus when the battery cell array is configured to operate in the first discharge mode and electrically connecting each battery cell in the first column of battery cells into a configuration that forms an electrical parallel connection between the first battery terminal and second battery terminal, where each battery cell, of the first column of battery cells, is in parallel between the first battery terminal and second battery terminal. The method also comprises electrically connecting the first battery terminal to a high-voltage bus when the battery cell array is configured to operate in the second discharge mode and electrically connecting each battery cell in the first column of battery cells into a configuration that forms an electrical series connection between the first battery terminal and second battery terminal, where the electrical series connection includes all the battery cells of the first column of battery cells. Moreover, the method also comprises electrically connecting the first battery terminal to the high-voltage bus when the battery cell array is configured to operate in the charge mode and electrically connecting each battery cell in the first column of battery cells into a configuration that forms an electrical series connection between the first battery terminal and second battery terminal, where the electrical series connection includes all the battery cells of the first column of battery cells. 
     Other devices, apparatuses, systems, methods, features, and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional devices, apparatuses, systems, methods, features, and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention may be better understood by referring to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the figures, like reference numerals designate corresponding parts throughout the different views. 
         FIG. 1  is a system block diagram of an example of an implementation of a reconfigurable battery system in accordance with the present disclosure. 
         FIG. 2  is a system block diagram of an example of an implementation of a battery cell array of the reconfigurable battery system in accordance with the present disclosure. 
         FIG. 3A  is a system block diagram of an example of an implementation of a battery cell array of the reconfigurable battery system, in a first discharge mode in accordance with the present disclosure. 
         FIG. 3B  is a system block diagram of an example of an implementation of the battery cell array of the reconfigurable battery system, in a charge mode in accordance with the present disclosure. 
         FIG. 3C  is a system block diagram of an example of an implementation of a battery cell array of the reconfigurable battery system, in a second discharge mode in accordance with the present disclosure. 
         FIG. 4  is a flowchart of an example of an implementation of a method of operation of the reconfigurable battery system in accordance with the present disclosure. 
         FIG. 5  is a flowchart of an example of an implementation of another method of operation of the reconfigurable battery system in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A reconfigurable battery system is disclosed. The reconfigurable battery system comprises a battery cell array and a bus switch. The battery cell array is configured to operate in a first discharge mode, a second discharge mode, and charge mode. The battery cell array includes a plurality of battery cells arranged as (1) at least a first column of battery cells between a second battery terminal and a first battery terminal and (2) a switch between each battery cell within the first column of battery cells. The bus switch is in signal communication with the battery cell array at the first battery terminal and is configured to select between electrically connecting the first battery terminal to a normal voltage bus or a high-voltage bus. The battery cell array may also include a plurality of battery cells arranged as a plurality of columns of battery cells between the second battery terminal and the first battery terminal, and the switches may be between each battery cell within each column of the plurality of columns of battery cells. 
     In an example of operation, the reconfigurable battery system may perform a method that comprises electrically connecting the first battery terminal to the normal voltage bus when the battery cell array is configured to operate in the first discharge mode and electrically connecting each battery cell in the first column of battery cells into a configuration that forms an electrical parallel connection between the first battery terminal and second battery terminal, where each battery cell, of the first column of battery cells, is in parallel between the first battery terminal and second battery terminal. The method also comprises electrically connecting the first battery terminal to a high-voltage bus when the battery cell array is configured to operate in the second discharge mode and electrically connecting each battery cell in the first column of battery cells into a configuration that forms an electrical series connection between the first battery terminal and second battery terminal, where the electrical series connection includes all the battery cells of the first column of battery cells. Moreover, the method also comprises electrically connecting the first battery terminal to the high-voltage bus when the battery cell array is configured to operate in the charge mode and electrically connecting each battery cell in the first column of battery cells into a configuration that forms an electrical series connection between the first battery terminal and second battery terminal, where the electrical series connection includes all the battery cells of the first column of battery cells. 
     In  FIG. 1 , a system block diagram of an example of an implementation of the reconfigurable battery system  100  is shown in accordance with the present disclosure. The reconfigurable battery system  100  may be part of, for example, an electric vehicle  101 . The reconfigurable battery system  100  is configured to be in signal communication with an electric vehicle load (generally referred to simply as a “load”)  102  and a charging station  104  via a plurality of electrical connections that include a normal voltage bus  106 , a load bus  108 , a high-voltage bus  110 , and a negative bus  111 . The reconfigurable battery system  100  may include a battery cell array  112 , a controller  114 , and a bus switch  116 . The controller  114  is in signal communication with the battery cell array  112  and the bus switch  116 . The bus switch  116  is also in signal communication with the battery cell array  112 , the load  102 , and the charging station  104  via a first battery terminal  118 , a second battery terminal  119 , the normal voltage bus  106 , the load bus  108 , the high-voltage bus  110 , and the negative bus  111 , respectively. In this example, the first battery terminal  118  may be a positive polarity terminal and the second battery terminal  119  may be a negative polarity terminal. 
     In this example, load  102  is a device that acts as an electrical load to the reconfigurable battery system  100 . Examples of the electric vehicle  101  may include an electric or hybrid automobile, truck, motorcycle, aircraft, marine vessel, etc. As such, examples of the load  102  may include, for example, one or more electric motor drives or other electric loads. Moreover, instead of a vehicle, the load  102  may be substituted with a non-vehicle device that utilizes electric power and desires a quick-charging and high-efficiency discharging battery system. Examples of this type of non-vehicle device may include stationary loads such as, for example, a solar powered system on a building and/or home or portable electrical and/or electronic loads. The charging station  104  may be a power supply, a charging station for electric vehicles such as, for example, a quick charger for electric cars, a solar system on a building and/or home, or other similar power-providing devices. Additionally, the charging station  104  may also be, for example, an on-board station or a DC bus on the aircraft system. 
     The battery cell array  112  includes a plurality of battery cells and at least one switch between at least two battery cells of the plurality of battery cells where the plurality of battery cells is arranged into at least a first column of battery cells. In general, the battery cell array includes two (2) times N by M battery cells arranged in one column of battery cells or a plurality of columns of battery cells, where N is a number of battery cells in each column of the plurality of columns of battery cells, and M is a number of columns of battery cells. In this example, both N and M are equal to at least one, such that the smallest battery cell array  112  is a 2×1 array of battery cells. 
     As such, the battery cell array  122  includes a plurality of battery cells with at least one switch between each battery cell or between a group of battery cells. As an example, in the situation where a switch is between each battery cell, if the battery cell array  112  is configured as a 2×1 array of battery cells, the battery cell array  112  includes a single switch between the two battery cells that are arranged as a single column of battery cells. If instead the battery cell array  112  is configured as a 4×1 array of battery cells, the battery cell array  112  is arranged as a single column of battery cells having three switches between the four battery cells in the single column of battery cells. Also, if instead the battery cell array  112  is configured as a 2×3 array of battery cells, the battery cell array  112  is arranged as three columns of battery cells, where each column of battery cells has two battery cells within the column. In this example, each column of battery cells would have a single switch between the two battery cells in each column, resulting in the battery cell array  112  having a total of three switches (i.e., one per column of battery cells). Furthermore, if instead the battery cell array  112  is configured as a 4×5 array of battery cells, the battery cell array  112  is arranged as five columns of battery cells, where each column of battery cells has four battery cells within the column. In this example, each column of battery cells would have three switches between the four battery cells in each column, resulting in the battery cell array  112  having a total of fifteen (15) switches (i.e., three per column of battery cells). 
     In an alternative example, if the at least one switch is between a group of battery cells, the same previous description would apply but instead on an array of individual battery cells. The battery cell array  122  may include an array of individual groups of battery cells, where each group of battery cells acts as single combined battery cell module that may have a greater voltage than an individual battery cell. For ease of illustration and description in the present application, the term “battery cell” is used to represent either an individual battery cell (i.e., a single battery) or an individual battery cell module (i.e., a single combined battery cell module including multiple single batteries within the battery cell module). 
     In this example, the at least one switch of the battery cell array  112  and the bus switch  116  may be, for example, electronic, electromechanical, or mechanical switches. As an example, the bus switch may be a single-pole-double-throw (SPDT) switch configured to connect the battery cell array  112  to the normal voltage bus  106  or the high-voltage bus  110 . Additionally, each switch of the battery cell array  112 , between each battery cell in the battery cell array  112 , may be, for example, a double-pole-double-throw (DPDT) switch. 
     The bus switch  116  is configured to electrically connect the battery cell array  112  to the normal voltage bus  106  when the battery cell array  112  is configured in either the first discharge mode or the second discharge mode. In this example, the first discharge mode is a mode of operation where the reconfigurable battery system  100  discharges power normally to the load  102 . Moreover, the second discharge mode is a mode of operation where the reconfigurable battery system  100  discharges power in a high-efficiency discharge mode. 
     Specifically, the bus switch  116  includes a first switch BS 1  and a second switch BS 2  that act approximately simultaneously. In an example of operation when discharging, the reconfigurable battery system  100  transmits power to the load  102  when the first switch BS 1  electrically connects the first battery terminal  118  to the normal voltage bus  106 , and the second switch BS 2  electrically connects the second battery terminal  119  to the load bus  108  of the load  102 . As an example of operation when charging, the reconfigurable battery system  100  receives power from the charging station  104  when the first switch BS 1  electrically connects the first battery terminal  118  to the high-voltage bus  110 , and the second switch BS 2  electrically connects the second battery terminal  119  to the negative bus  111  of the charging station  104 . 
     It is appreciated by those of ordinary skill in the art that as batteries discharge, their battery voltages decrease and near the end of a battery&#39;s discharge capacity, the battery voltage can be as low as 40% of its voltage at a fully charged state. At this lower voltage, the battery current becomes large under a constant power load, and this increased current produces significantly more heat at the battery and at any equipment electrically connected to the battery, as compared to the heat produced when the battery voltage is higher and near the fully charged state of the battery. 
     The adverse effects of this increased heat production includes, for example, loss of energy resulting in lower battery efficiency, increased need for system cooling that requires the consumption of more power, increased equipment current ratings, and accelerated equipment degradation resulting in a shortened cycle life for the equipment. The reconfigurable battery system  100  addresses these problems by switching the discharge operation from the normal discharge mode when the battery cell array has a level of the state of charge that is above a predetermined value to the high-efficiency discharge mode when the battery cell array has a level of the state of charge that is below the predetermined value. 
     The high-efficiency discharge mode results in the battery cell array  112  producing a higher voltage and corresponding lower current while discharging at lower levels of the state of charge to the same load (i.e., the load  102 ). This produces the same amount of power that is delivered to the load  102  without correspondingly producing any additional heat when the battery cell array  112  has a level of the state of charge that is below the predetermined value. 
     In this example, when battery cell array  112  is configured in the first discharge mode (i.e., the normal discharge mode), the switch between each battery cell, within the battery cell array  112 , is configured to electrically connect each battery cell in the first column of battery cells into a configuration that forms an electrical parallel connection between the first battery terminal and second battery terminal. In this configuration, each battery cell, of the first column of battery cells, is in parallel between the first battery terminal  118  and the second battery terminal  119 . Additionally, if there are multiple columns of battery cells, each battery cell, of each of the columns of battery cells, are also in parallel between the first battery terminal  118  and the second battery terminal  119 . 
     If instead, the battery cell array  112  is configured in the second discharge mode (i.e., the high-efficiency mode), the switch between each battery cell is configured to electrically connect each battery cell in the first column of battery cells into a configuration that forms an electrical series connection between the first battery terminal  118  and the second battery terminal  119 . In this configuration, the electrical series connection includes all the battery cells of the first column of battery cells. Additionally, if there are multiple columns of battery cells, each battery cell, of each of the columns of battery cells, are also in series between the first battery terminal  118  and the second battery terminal  119 . 
     In this example, when the reconfigurable battery system  100  is configured to operate in the charge mode, the bus switch  116  is configured to electrically connect the first battery terminal  118  of the battery cell array  112  to the high-voltage bus  110 . When the battery cell array  112  is configured in the charge mode, similar to the configuration of the battery cell array  112  in the second discharge mode, the switch between each battery cell is configured to electrically connect each battery cell in the first column of battery cells into a configuration that forms an electrical series connection between the first battery terminal  118  and the second battery terminal  120 . The electrical series connection includes all the battery cells of the first column of battery cells. Additionally, if there are multiple columns of battery cells, each battery cell, of each of the columns of battery cells, are also in series between the first battery terminal  118  and the second battery terminal  119 . 
     In the charge mode configuration, the battery cell array  112  is configured to allow the columns of battery cells to be charged at a higher voltage (i.e., a high-voltage value) than would normally be possible if each individual battery cell were being charged separately at the voltage rating of the individual battery cells. It is appreciated by those of ordinary skill in the art that the voltage across the terminals of a plurality of battery cells that are electrically connected in series is equal to the total voltage of combination of the individual voltages of each battery cells. For example, if four battery cells are electrically connected in series and each battery cell has a voltage of 5 volts, the total voltage produced by the combination of the battery cells in series is 20 volts. As a result, the battery cell array  112  is capable of being charged at a higher voltage than the voltage rating of the individual battery cells. Since power is equal to the voltage multiplied by the current, the same amount of power may be delivered to the battery cell array  112  (i.e., charged) with a higher voltage and lower current value delivered to the battery cell array  112  from the charging station  104 . Since the current is lower for the same amount of power, the battery cell array  112  may be charged with higher efficiency since the lower current generates less heat. This also results in the battery cell array  112  being charged in less time (i.e., faster) than the time required by conventional approaches, assuming the same available charging current limit of a charging station is applied. In this example, the number of battery cells arranged into columns of battery cells is directly related to a maximum charge voltage that may be utilized to efficiently and quickly charge the battery cell array  112 . Utilizing this technique, the battery cell array  112  may configured to charge at twice, four times, six times, eight times, etc., the voltage rating of the individual battery cells. In general, the charging voltage may be increased by a factor of two times the number of battery cells in a column of battery cells. This technique also allows the battery cell array  112  to be charged with a higher amount of power because the configuration allows for the use of the same amount of current that is utilized in a normal charge process while utilizing a higher voltage than the rated voltage of the individual battery cells. 
     In this example, the controller  114  may be any type of controlling device such as a microprocessor, application-specific integrated circuit (ASIC), programmable gate array (PGA), logic circuit, or other similar device. The controller  114  is in signal communication with the at least one switch between each battery cell in the battery cell array  112  and the bus switch  116 . The controller  114  may be configured to control the switch between each battery cell and the bus switch  116  based on the operation of the battery cell array  112  in the first discharge mode, the second discharge mode, or the charge mode. The controller  114  may also be configured to determine a level of the state of charge within the battery cell array  112  and select the first discharge mode or the second discharge mode in response to the level of the state of charge within the battery cell array  112 . 
     The controller  114  may also be configured as a control system that includes a switch controller (not shown), battery system controller (not shown), and vehicle controller (not shown). These controllers may be separate devices, modules, or components or sub-components or modules of the controller  114 . In general, the first switch BS 1 , the second switch BS 2 , and the switches within the battery cell array  112  are controlled by the switch controller that is a controller of the battery system controller. The battery system controller may receive command signals from the vehicle controller and other sensors within or associated with the reconfigurable battery system  100 . As an example, the battery system controller may receive command signals that include voltage, current, state of charge, temperature, pressure, and other information related to the reconfigurable battery system  100 , electric vehicle  101 , and load  102 . 
     It is appreciated by those of ordinary skill in the art that the circuits, components, modules, and/or devices of, or associated with, the reconfigurable battery system  100  are described as being in signal communication with each other, where signal communication refers to any type of communication and/or connection between the circuits, components, modules, and/or devices that allows a circuit, component, module, and/or device to pass and/or receive signals and/or information from another circuit, component, module, and/or device. The communication and/or connection may be along any signal path between the circuits, components, modules, and/or devices that allows signals and/or information to pass from one circuit, component, module, and/or device to another and includes wireless or wired signal paths. The signal paths may be physical, such as, for example, conductive wires, electromagnetic wave guides, cables, attached and/or electromagnetic or mechanically coupled terminals, semi-conductive or dielectric materials or devices, or other similar physical connections or couplings. Additionally, signal paths may be non-physical such as free-space (in the case of electromagnetic propagation) or information paths through digital components where communication information is passed from one circuit, component, module, and/or device to another in varying digital formats, without passing through a direct electromagnetic connection. 
     In  FIG. 2 , a system block diagram of an example of an implementation of a battery cell array  200  of the reconfigurable battery system  100  is shown in accordance with the present disclosure. In this example, the battery cell array  200  is in signal communication with the bus switch  116 , where the bus switch  116  is configured to select between the normal voltage bus  106  and the high-voltage bus  110 . The battery cell array  200  includes the first battery terminal  118  and the second battery terminal  119 . In this example, the battery cell array  200  is configured as a 4×5 array of battery cells that includes twenty (20) battery cells B 11 , B 12 , B 13 , B 14 , B 15 , B 21 , B 22 , B 23 , B 24 , B 25 , B 31 , B 32 , B 33 , B 34 , B 35 , B 41 , B 42 , B 43 , B 44 , and B 45  and fifteen (15) switches S 11 , S 12 , S 13 , S 14 , S 15 , S 21 , S 22 , S 23 , S 24 , S 25 , S 31 , S 32 , S 33 , S 34 , and S 35 , where each switch is electrically connected between adjacent battery cells in a column. In this example, the battery cell array  200  includes five (5) columns of battery cells. The first column of battery cells  202  includes battery cells B 11 , B 21 , B 31 , and B 41  and switches S 11 , S 21 , and S 31 . The second column of battery cells  204  includes B 12 , B 22 , B 32 , and B 42  and S 12 , S 22 , and S 32 . The third column of battery cells  206  includes B 13 , B 23 , B 33 , and B 43  and S 13 , S 23 , and S 33 . The fourth column of battery cells  208  includes B 14 , B 24 , B 34 , and B 44  and S 14 , S 24 , and S 34 . The fifth column of battery cells  210  includes B 15 , B 25 , B 35 , and B 45  and S 15 , S 25 , and S 35 . In this example, all the columns of battery cells  202 ,  204 ,  206 ,  208 , and  210  are electrically connected between the first battery terminal  118  and the second battery terminal  119 . As discussed earlier, each battery cell B 11 , B 12 , B 13 , B 14 , B 15 , B 21 , B 22 , B 23 , B 24 , B 25 , B 31 , B 32 , B 33 , B 34 , B 35 , B 41 , B 42 , B 43 , B 44 , and B 45  may be an individual battery cell (i.e., an individual battery) or a battery cell module (i.e., an individual battery cell module including more than one battery cell in the module). 
     Turning to  FIGS. 3A-3C , a system block diagram of an example of an implementation of another battery cell array  300  of the reconfigurable battery system  100  is shown in accordance with the present disclosure. As discussed earlier, the battery cell array  300  may include any number of battery cells and switches where, in general, the battery cell array  300  includes 2 times N times M battery cells arranged in one column of battery cells or a plurality of columns of battery cells, where N is a number of battery cells in each column of the plurality of columns of battery cells, and M is a number of columns of battery cells. Both N and M are equal to at least one (1) such that the smallest battery cell array  112  is a 2×1 array of battery cells. In this example, for ease of illustration, the battery cell array  300  is a 2×3 array of battery cells including battery cells B 11 , B 21 , B 22 , B 22 , B 13 , and B 23  and switches S 1 , S 2 , and S 3 . The battery cells B 11  and B 21  and switch S 1  are arranged in a first column  302  of battery cells, the battery cells Biz and B 22  and switch S 2  are arranged in a second column  304  of battery cells, and the battery cells B 13  and B 23  and switch S 3  are arranged in a third column  306  of battery cells. In this example, the bus switch  116  is a SPDT switch and each switch S 1 , S 2 , and S 3  of the battery cell array  112  is a DPDT switch. 
     In  FIG. 3A , the battery cell array  300  is configured in the first discharge mode in accordance with the present disclosure. As discussed earlier, the first discharge mode may be a normal discharge mode where the battery cell array  300  produces an output power signal  308  that is equal to a voltage across the second battery terminal  119  and the first battery terminal  118  multiplied by the current produced by the battery cell array  300 . This output power signal  308  is transmitted to the normal voltage bus  106  when the bus switch  116  electrically connects the first battery terminal  118  to the normal voltage bus  106  via the first switch BS 1  and second battery terminal  119  to the load bus  108  via the second switch BS 2 . The output power signal  308  is then transmitted to the load  102 . 
     In the first discharge mode, the switch S 1  between the battery cells B 11  and B 21  is configured to electrically connect each battery cell B 11  and B 21  in the first column  302  into a configuration that forms an electrical parallel connection between the first battery terminal  118  and the second battery terminal  119 . Specifically, the battery cells B 11  and B 21  of the first column  302  are configured in parallel to each other between the first battery terminal  118  and the second battery terminal  119 . Similarly, the second switch S 2  between the battery cells B 12  and B 22  is configured to electrically connect each battery cell B 12  and B 22  in the second column  304  into a configuration that forms an electrical parallel connection between the first battery terminal  118  and the second battery terminal  119 . Moreover, third switch S 3  between the battery cells B 13  and B 23  is configured to electrically connect each battery cell B 13  and B 23  in the third column  306  into a configuration that forms an electrical parallel connection between the first battery terminal  118  and the second battery terminal  119 . 
     The result is that every battery cell B 11 , B 21 , B 12 , B 22 , B 13 , and B 23  is configured to be in parallel between the first battery terminal  118  and the second battery terminal  119 . In this example, the discharge voltage at the normal voltage bus  106  would be equal to the rated voltage of the individual battery cells B 11 , B 21 , B 12 , B 22 , B 13 , and B 23 . 
     In  FIG. 3B , the battery cell array  300  is configured in a charge mode in accordance with the present disclosure. As discussed earlier, the charge mode is an efficient charge mode that allows the battery cell array  300  to be charged efficiently and quickly utilizing a higher voltage than the voltage rating of the individual battery cell of the battery cell array  300 . 
     In the charge mode, the bus switch  116  is configured to electrically connect the first battery terminal  118  of the battery cell array  300  to the high-voltage bus  110  where the battery cell array  300  is configured to charge at a high-voltage value. Specifically, in the charge mode, the battery cell array  300  receives a power signal  310  from the charging station  104  when the bus switch  116  electrically connects the first battery terminal  118  to the high-voltage bus  110  via the first switch BS 1  and the second battery terminal  119  to the negative bus  111  via the second switch BS 2 . 
     In this example, the first switch S 1  between the battery cells B 11  and B 21  is configured to electrically connect the battery cells B 11  and B 21  in the first column  302  into a configuration that forms an electrical series connection between the first battery terminal  118  and the second battery terminal  119 . Similarly, the second switch S 2  between the battery cells B 12  and B 22  is configured to electrically connect the battery cells B 12  and B 22  in the second column  304  into a configuration that forms an electrical series connection between the first battery terminal  118  and the second battery terminal  119 . Moreover, the third switch S 3  between the battery cells B 13  and B 23  is configured to electrically connect the battery cells B 13  and B 23  in the third column  306  into a configuration that forms an electrical series connection between the first battery terminal  118  and the second battery terminal  119 . 
     The result is that every battery cell of the columns is configured to be in series between the first battery terminal  118  and the second battery terminal  119 . In this example, the charging voltage from the high-voltage bus  110  may be twice the rated voltage of the individual battery cells B 11 , B 21 , B 12 , B 22 , B 13 , and B 23  allowing for the charging station  104  to use a higher voltage charging power signal  310  to charge the battery cell array  300  in less time than conventional charging methods at the same charging station current limit. 
     In  FIG. 3C , the battery cell array  300  is configured in a second discharge mode in accordance with the present disclosure. As discussed earlier, the second discharge mode is a high-efficiency discharge mode where the battery cell array  300  produces a new output power signal  312  that is again equal to a voltage across the second battery terminal  119  and the first battery terminal  118  multiplied by the current produced by the battery cell array  300 , where the voltage across the second battery terminal  119  and the first battery terminal  118  is higher than the voltage described in relation to  FIG. 3A  when the battery cell array  300  has a level of the state of charge that is below the predetermined value. This new output power signal  312  is transmitted to the normal voltage bus  106  when the bus switch  116  electrically connects the first battery terminal  118  to the normal voltage bus  106 . The new output power signal  312  is then transmitted to the load  102 . 
     As in the first discharge mode, for the second discharge mode, the bus switch  116  is configured to electrically connect the first battery terminal  118  of the battery cell array  300  to the high-voltage bus  110  where the battery cell array  300  is configured to charge at a high-voltage value. Again, the new output power signal  312  is transmitted to the normal voltage bus  106  when the bus switch  116  electrically connects the first battery terminal  118  to the normal voltage bus  106  via the first switch BS 1  and second battery terminal  119  to the load bus  108  via the second switch BS 2 . 
     Similar to the first charge mode, in this example, the first switch S 1  between the battery cells B 11  and B 21  is configured to electrically connect the battery cells B 11  and B 21  in the first column  302  into a configuration that forms an electrical series connection between the first battery terminal  118  and the second battery terminal  119 . Similarly, the second switch S 2  between the battery cells B 12  and B 22  is configured to electrically connect the battery cells B 12  and B 22  in the second column  304  into a configuration that forms an electrical series connection between the first battery terminal  118  and the second battery terminal  119 . Moreover, the third switch S 3  between the battery cells B 13  and B 23  is configured to electrically connect the battery cells B 13  and B 23  in the third column  306  into a configuration that forms an electrical series connection between the first battery terminal  118  and the second battery terminal  119 . 
     Again, the result is that every battery cell of the columns is configured to be in series between the first battery terminal  118  and the second battery terminal  119 . In this example, the output voltage from the first battery terminal  118  may be as much as twice the available voltage of the individual battery cells B 11 , B 21 , B 12 , B 22 , B 13 , and B 23  allowing for battery cell array  300  to provide a relatively constant new output power signal  312  to the load  102  as the level of the state charge of the battery cell array  300  drops below the predetermined value. 
     In these examples, the predetermined value of the level of the state of charge of the battery cell array  300  may be a percentage threshold of the fully charged state of the battery cell array  300 . This percentage threshold may be predefined based on the design of the battery cells and/or the battery cell array  300 . 
     In these configurations, the controller  114  is configured to control the switch between each pair of adjacent battery cells of each column and the bus switch  116  based on the operation of the battery cell array  300  in the first discharge mode, the second discharge mode, or the charge mode. The controller  114  is also configured to determine a level of the state of charge within the battery cell array  300  and select the first discharge mode or the second discharge mode in response to the level of the state of charge within the battery cell array  300 . 
     Turning to  FIG. 4 , a flowchart of an example of an implementation of a method  400  of operation of the reconfigurable battery system  100  is shown in accordance with the present disclosure. The method  400  starts by electrically connecting  402  the first battery terminal  118  to the normal voltage bus  106  when the battery cell array  112 ,  200 , or  300  is configured to operate in the first discharge mode and, approximately simultaneously, electrically connecting each battery cell in each column of battery cells into a configuration that forms an electrical parallel connection between the first battery terminal  118  and the second battery terminal  119 , where each battery cell, of each column of battery cells, is in parallel between the first battery terminal  118  and second battery terminal  119 . The method  400  then transmits  404  the output power signal  308  to the load  102  and monitors (via decision step  406 ) the level of the state of charge of the battery cell array  112 ,  200 , or  300  to determine if the level of the state of charge falls below the predetermined value. If the level of the state of charge falls below the predetermined value, select  408  the second discharge mode. The method  400  then transmits  410  the new output power signal  312  to the load  102 . The method  400  then determines (via decision step  412 ) if the battery cell array  112 ,  200 , or  300  needs charging. If the battery cell array  112 ,  200 , or  300  needs charging, the method  400  electrically connects  414  the first battery terminal to the high-voltage bus  110  and, approximately simultaneously, electrically connects each battery cell in the first column of battery cells into a configuration that forms an electrical series connection between the first battery terminal and second battery terminal, where the electrical series connection includes all the battery cells of the first column of battery cells. It is appreciated by those of ordinary skill that if the reconfigurable battery system  100  is already in the second discharge mode, only the first battery terminal  118  is connected to the high-voltage bus  110  because the battery cells of the battery cell array  112 ,  200 , or  300  are already configured in a series connection. The method  400  then receives  416  the charging power signal  310  from the charging station  104  and charges the battery cell array  112 ,  200 , or  300 . The method  400  then returns to step  402  and method repeats. 
     If, in decision step  412 , the battery cell array  112 ,  200 , or  300  does not need charging, the method  400  returns to step  410  and continues to transmit the new output power signal  312  to the load  102  and the method  400  repeats. If, in decision step  406 , the level of the state of charge does not fall below the predetermined value, the method  400  returns to step  404  and continues to transmit  404  the output power to the electric load and the method repeats. 
     In  FIG. 5 , a flowchart of an example of an implementation of another method  500  of operation of the reconfigurable battery system  100  is shown in accordance with the present disclosure. The method  500  starts by loading  502  data into the controller  114 . The loaded data includes, for example, a reference voltage (V ref ) that is utilized to trigger reconfiguration of the reconfigurable battery system  100 , a battery upper voltage limit (V UL ), a battery lower voltage limit (V LL ), and a mode of operation (MODE) where the MODE designates whether to charge or discharge the battery cell array  112 ,  200 , or  300 . The controller  114  then determines (in decision step  504 ) whether the MODE is in discharge mode. If the MODE is in discharge mode, the controller  114  sets  506  the battery cell array  112 ,  200 , or  300  and bus switch  116  of the reconfigurable battery system  100  to the first discharge mode described earlier in regard to the example shown in  FIG. 3A . The controller  114  then receives  508  a measured battery voltage (V b ) from a battery voltage sensor. The battery voltage sensor may be part of or associated with the reconfigurable battery system  100 . The controller  114  then (in decision step  510 ) compares V b  against V REF  to determine if V b  is less than or equal to V REF . If V b  is greater than V REF , the controller  114  continues to maintain the reconfigurable battery system  100  in the first discharge mode and the method returns to step  508  where the V b  is again measured. 
     If instead V b  is less than or equal to V REF , the controller  114  reconfigures  512  the battery cell array  112 ,  200 , or  300  and bus switch  116  of the reconfigurable battery system  100  to the second discharge mode to increase the discharge voltage described earlier in regard to the example shown in  FIG. 3B . The controller  114  then (in decision step  514 ) compares V b  against V LL  to determine if V b  is less than or equal to V LL . V LL  is a cutoff voltage, and if V b  is less than or equal to V LL , the controller  114  stops discharging the battery cell array  112 ,  200 , or  300 , and the process ends. 
     If, instead the controller  114  determines (in decision step  504 ) that the MODE is not in discharge mode, the controller  114  sets  516  the battery cell array  112 ,  200 , or  300  and bus switch  116  of the reconfigurable battery system  100  to the charge mode. Once in charge mode, the controller receives  518  the V b  from a battery voltage sensor and compares (in decision step  520 ) V b  against V UL . If V b  is less than or equal to V UL , the controller  114  reconfigures  522  the battery cell array  112 ,  200 , or  300  and bus switch  116  of the reconfigurable battery system  100  to high voltage charging as described earlier in regard to the example shown in  FIG. 3C . After charging, the method ends. 
     If, instead the controller  114  determines (in decision step  520 ) that V b  is greater than V UL , the controller  114  stops charging the battery cell array  112 ,  200 , or  300  and the process ends. 
     It will be understood that various aspects or details of the disclosure may be changed without departing from the scope of the disclosure. It is not exhaustive and does not limit the claimed disclosures to the precise form disclosed. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation. Modifications and variations are possible in light of the above description or may be acquired from practicing the disclosure. The claims and their equivalents define the scope of the disclosure. Moreover, although the techniques have been described in language specific to structural features and/or methodological acts, it is to be understood that the appended claims are not necessarily limited to the features or acts described. Rather, the features and acts are described as example implementations of such techniques. 
     Further, the disclosure comprises embodiments according to the following clauses. 
     Clause 1. A reconfigurable battery system comprising: a battery cell array configured to operate in a first discharge mode, a second discharge mode, and a charge mode, wherein the battery cell array includes: a plurality of battery cells arranged as at least a first column of battery cells between a first battery terminal and a second battery terminal; and a switch between each battery cell within the first column of battery cells; and a bus switch in signal communication with the battery cell array at the first battery terminal, wherein the bus switch is configured to select between electrically connecting the first battery terminal to a normal voltage bus or a high-voltage bus. 
     Clause 2. The reconfigurable battery system of clause 1, wherein the bus switch is a single-pole-double-throw (SPDT) switch. 
     Clause 3. The reconfigurable battery system of clause 1, wherein the switch between each battery cell is a double-pole-double-throw (DPDT) switch. 
     Clause 4. The reconfigurable battery system of clause 1, further comprising: a controller in signal communication with the switch between each battery cell and the bus switch; wherein the controller is configured to: control the switch between each battery cell and the bus switch based on the operation of the battery cell array in the first discharge mode, the second discharge mode, or the charge mode; determine a level of a state of charge within the battery cell array; and select the first discharge mode or the second discharge mode in response to the level of the state of charge within the battery cell array. 
     Clause 5. The reconfigurable battery system of clause 1, wherein the bus switch is configured to electrically connect the battery cell array to the normal voltage bus when the battery cell array is configured in the first discharge mode or the second discharge mode. 
     Clause 6. The reconfigurable battery system of clause 5, wherein: the battery cell array is configured in the first discharge mode; and the switch between each battery cell electrically connects each battery cell in the first column of battery cells into a configuration that forms an electrical parallel connection between the first battery terminal and the second battery terminal. 
     Clause 7. The reconfigurable battery system of clause 5, wherein: the battery cell array is configured in the second discharge mode; and the switch between each battery cell electrically connects each battery cell in the first column of battery cells into a configuration that forms an electrical series connection between the first battery terminal and the second battery terminal. 
     Clause 8. The reconfigurable battery system of clause 1, wherein the bus switch is configured to electrically connect the battery cell array to the high-voltage bus when the battery cell array is configured to charge at a high-voltage value. 
     Clause 9. The reconfigurable battery system of clause 8, wherein the switch between each battery cell electrically connects each battery cell in the first column of battery cells into a configuration that forms an electrical series connection between the first battery terminal and the second battery terminal. 
     Clause 10. A reconfigurable battery system comprising: a battery cell array configured to operate in a first discharge mode, a second discharge mode, and a charge mode, wherein the battery cell array includes: a plurality of battery cells arranged as a plurality of columns of battery cells between a second battery terminal and a first battery terminal; and a switch between each battery cell within each column of the plurality of columns of battery cells; and a bus switch in signal communication with the battery cell array at the first battery terminal, wherein the bus switch is configured to select between electrically connecting the first battery terminal to a normal voltage bus or a high-voltage bus. 
     Clause 11. The reconfigurable battery system of clause 10, wherein: the battery cell array includes 2 times N times M battery cells; N is a number of battery cells in each column of the plurality of columns of battery cells; and M is a number of columns of battery cells. 
     Clause 12. The reconfigurable battery system of clause 10, further comprising a controller in signal communication with the switch between each battery cell and the bus switch, wherein the controller is configured to control the switch between each battery cell and the bus switch based on the operation of the battery cell array in the first discharge mode, the second discharge mode, or the charge mode. 
     Clause 13. The reconfigurable battery system of clause 10, wherein the bus switch is configured to electrically connect the battery cell array to the normal voltage bus when the battery cell array is configured in the first discharge mode or the second discharge mode. 
     Clause 14. The reconfigurable battery system of clause 13, wherein: the battery cell array is configured in the first discharge mode; and the switch between each battery cell electrically connects each battery cell in each column of the plurality of columns of battery cells into a configuration that forms an electrical parallel connection between the first battery terminal and second battery terminal. 
     Clause 15. The reconfigurable battery system of clause 13, wherein: the battery cell array is configured in the second discharge mode; the switch between each battery cell electrically connects each battery cell in each column of the plurality of columns of battery cells into a configuration that forms a plurality of electrical series connections between the first battery terminal and the second battery terminal. 
     Clause 16. The reconfigurable battery system of clause 10, wherein the bus switch is configured to electrically connect the battery cell array to the high-voltage bus when the battery cell array is configured to charge at a high-voltage value. 
     Clause 17. The reconfigurable battery system of clause 16, wherein the switch between each battery cell electrically connects each battery cell in each column of the plurality of columns of battery cells into a configuration that forms a plurality of electrical series connections between the first battery terminal and the second battery terminal. 
     Clause 18. A method for charging or discharging a reconfigurable battery system having a battery cell array configured to operate in a first discharge mode, a second discharge mode, or a charge mode, wherein the battery cell array has a plurality of battery cells arranged as at least a first column of battery cells between a first battery terminal and a second battery terminal, the method comprising: when the battery cell array is configured to operate in the first discharge mode, electrically connecting the first battery terminal to a normal voltage bus and electrically connecting each battery cell in the first column of the battery cells into a configuration that forms an electrical parallel connection between the first battery terminal and the second battery terminal, wherein each battery cell, of the first column of battery cells, is in parallel between the first battery terminal and the second battery terminal; when the battery cell array is configured to operate in the second discharge mode, electrically connecting the first battery terminal to the normal voltage bus and electrically connecting each battery cell in the first column of the battery cells into a configuration that forms an electrical series connection between the first battery terminal and the second battery terminal, wherein the electrical series connection includes all the battery cells of the first column of battery cells; and when the battery cell array is configured to operate in the charge mode, electrically connecting the first battery terminal to a high-voltage bus and electrically connecting each battery cell in the first column of battery cells into a configuration that forms an electrical series connection between the first battery terminal and the second battery terminal, wherein the electrical series connection includes all the battery cells of the first column of battery cells. 
     Clause 19. The method of clause 18, wherein electrically connecting each battery cell in the first column of battery cells into a configuration that forms an electrical series connection between the first battery terminal and the second battery terminal includes: determining a level of a state of charge within the battery cell array; and selecting the second discharge mode in response to the level of the state of charge being below or equal to a predetermined value. 
     Clause 20. The method of clause 19, further including transmitting a new output power signal to the load, wherein electrically connecting the first battery terminal to a high-voltage bus and electrically connecting each battery cell in the first column of battery cells into a configuration that forms an electrical series connection between the first battery terminal and the second battery terminal includes: determining if the battery cell array needs charging; and selecting the charge mode in response to determining that the battery cell array needs charging. 
     To the extent that terms “includes,” “including,” “has,” “contains,” and variants thereof are used herein, such terms are intended to be inclusive in a manner similar to the term “comprises” as an open transition word without precluding any additional or other elements. Moreover, conditional language such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, are understood within the context to present that certain examples include, while other examples do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that certain features, elements, and/or steps are in any way required for one or more examples or that one or more examples necessarily include logic for deciding, with or without user input or prompting, whether certain features, elements, and/or steps are included or are to be performed in any particular example. Conjunctive language such as the phrase “at least one of X, Y, or Z,” unless specifically stated otherwise, is to be understood to present that an item, term, etc., may be either X, Y, or Z, or a combination thereof.