Patent Publication Number: US-2021175783-A1

Title: Motor control for gas engine replacement device based on battery pack configuration data

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/946,226, filed Dec. 10, 2019, the entire content of which is hereby incorporated by reference. 
    
    
     FIELD 
     The present application relates to gas engine replacement motor units and, more particularly, to gas engine replacement motor units for use with power equipment. 
     BACKGROUND 
     Currently, several outdoor power equipment (e.g., lawn and garden equipment) and construction equipment (e.g., concrete mixers, plate compactors) include a gas engine to run the power equipment. However, gas engines produce emissions and are not generally adaptable for optimal performance of the power equipment. 
     SUMMARY 
     Gas engine replacement devices, also referred to as powerheads, that are powered by lithium-ion battery packs and that use electric brushless motors provide several advantages over gas engines when powering the equipment. However, a battery powered gas engine replacement device may have limited runtime when compared to similar sized gasoline powered engine. The energy density of gasoline is higher than current lithium-ion battery chemistry or other widely available battery technology. 
     In some embodiments, a gas-engine replacement device is provided including a housing, a battery receptacle coupled to the housing and configured to removably connect to a battery pack having a memory storing battery pack configuration data, a motor located within the housing, a power take-off shaft receiving torque from the motor and protruding from a side of the housing, a power switching network configured to selectively provide power from the battery pack to the motor, and an electronic processor. The electronic processor is coupled to the power switching network and configured to control the power switching network to rotate the motor. The electronic processor is configured to receive the battery pack configuration data responsive to a connection of the battery pack to the battery receptacle and control the electric motor based on the battery pack configuration data. 
     In some embodiments, a gas-engine replacement device is provided including a housing, a battery receptacle coupled to the housing and configured to removably connect to a battery pack including a first electronic processor, a motor located within the housing, a power take-off shaft receiving torque from the motor and protruding from a side of the housing, a power switching network configured to selectively provide power from the battery pack to the motor, and a second electronic processor. The first electronic processor is configured to communicate battery pack configuration data to the second electronic processor responsive to a connection of the battery pack to the battery receptacle. The second electronic processor is coupled to the power switching network and configured to control the power switching network to rotate the motor based on the battery pack configuration data. The first electronic processor is configured to monitor a condition of the battery pack and communicate revised battery pack configuration data to the second electronic processor responsive to the condition violating a threshold. The second electronic processor is configured to control the electric motor based on the revised battery pack configuration data. 
     In some embodiments, a gas-engine replacement device is provided including a housing, a battery receptacle coupled to the housing and configured to removably connect to a battery pack including a first electronic processor, a motor located within the housing, a power take-off shaft receiving torque from the motor and protruding from a side of the housing, a power switching network configured to selectively provide power from the battery pack to the motor, and a second electronic processor. The second electronic processor is coupled to the power switching network and configured to control the power switching network to rotate the motor. One of the first or second electronic processors is configured to detect a connection of the battery pack and, in response, the first electronic processor is configured to communicate battery pack configuration data to the second electronic processor. The second electronic processor is configured to control the electric motor based on the battery pack configuration data. 
     Before any embodiments are explained in detail, it is to be understood that the embodiments are not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. Embodiments described herein are capable of being practiced in or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limited. The use of “including,” “comprising” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “mounted,” “connected” and “coupled” are used broadly and encompass both direct and indirect mounting, connecting and coupling. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings, and can include electrical connections or couplings, whether direct or indirect. Additionally, as used herein with a list of items, “and/or” means that the items may be taken all together, in sub-sets, or as alternatives (for example, “A, B, and/or C” means A; B; C; A and B; B and C; A and C; or A, B, and C). 
     It should be noted that a plurality of hardware and software based devices, as well as a plurality of different structural components may be utilized to implement embodiments described herein. Furthermore, and as described in subsequent paragraphs, the specific configurations illustrated in the drawings are intended as example embodiments and other alternative configurations are possible. The terms “processor” “central processing unit” and “CPU” are interchangeable unless otherwise stated. Where the terms “processor” or “central processing unit” or “CPU” are used as identifying a unit performing specific functions, it should be understood that, unless otherwise stated, those functions can be carried out by a single processor, or multiple processors arranged in any form, including parallel processors, serial processors, tandem processors or cloud processing/cloud computing configurations. 
     In addition, it should be understood that embodiments may include hardware, software, and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic-based aspects may be implemented in software (e.g., stored on non-transitory computer-readable medium) executable by one or more processing units, such as a microprocessor and/or application specific integrated circuits (“ASICs”). As such, it should be noted that a plurality of hardware and software based devices, as well as a plurality of different structural components, may be utilized to implement the embodiments. 
     Other features and aspects will become apparent by consideration of the following detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a gas engine replacement device in accordance with an embodiment. 
         FIG. 2  is a plan view of the gas engine replacement device of  FIG. 1 . 
         FIG. 3  is a schematic view of the gas engine replacement device of  FIG. 1 . 
         FIG. 4  is a perspective view of a battery pack of the gas engine replacement device of  FIG. 1 . 
         FIG. 5  is a cross-sectional view of the battery pack of  FIG. 4 . 
         FIG. 6  is a cross-sectional view of a battery receptacle of the gas engine replacement device of  FIG. 1 . 
         FIG. 7  is a cross-sectional view of a motor of the gas engine replacement device of  FIG. 1 . 
         FIG. 8  is a schematic view of a motor, a gear train, and a power take-off shaft of the gas engine replacement device of  FIG. 1 . 
         FIG. 9  is a block diagram of the gas engine replacement device of  FIG. 1 . 
         FIG. 10  is a flowchart of an example method for battery pack configuration control in the gas engine replacement device of  FIG. 1 . 
         FIG. 11  illustrates a pump system including the gas engine replacement device of  FIG. 1 . 
         FIG. 12  illustrates a mixing system including the gas engine replacement device of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     As shown in  FIGS. 1 and 2 , a gas engine replacement device  10  for use with a piece of power equipment includes a housing  14  with a first side  18 , a second side  22  adjacent the first side  18 , a third side  26  opposite the second side  22 , a fourth side  28  opposite the first side  18 , a fifth side  30  extending between the second and third sides  22 ,  26 , and a sixth side  32  opposite the fifth side  30 . The gas engine replacement device  10  also includes a flange  34  coupled to the housing  14  on the first side  18 , an electric motor  36  located within the housing  14 , and a power take-off shaft  38  that protrudes from the second side  22  and receives torque from the motor  36 . As explained in further detail below, in some embodiments, the power take-off shaft  38  protrudes from the first side  18  and from the flange  34 . As shown in  FIG. 3 , the gas engine replacement device  10  also includes control electronics  42  positioned within the housing  14  and including wiring and a controller  46  that is electrically connected to the motor  36 . A similar gas engine replacement device  10  is described and illustrated in U.S. patent application Ser. No. 16/551,197, filed Aug. 26, 2019, the entire content of which is incorporated herein by reference. 
     As shown in  FIGS. 1-6 , the gas engine replacement device  10  also includes a battery pack  50  that is removably connected to a battery receptacle  54  in the housing  14  to transfer current from the battery pack  50  to the motor  36  via the control electronics  42 . In some embodiments, multiple battery packs  50  are connected to multiple battery receptacles  54  in the housing  14 . With reference to  FIGS. 4-6 , the battery pack  50  includes a battery pack housing  58  with a support portion  62  and a first terminal  66  that is electrically connected to a plurality of battery cells  68  supported by the battery pack housing  58 . The support portion  62  provides a slide-on arrangement with a projection/recess portion  70  cooperating with a complementary projection/recess portion  74  (shown in  FIG. 6 ) of the battery receptacle  54 . In the embodiment illustrated in  FIGS. 4-6 , the projection/recess portion  70  of the battery pack  50  is a guide rail and the projection/recess portion  74  of the battery receptacle  54  is a guide recess. A similar battery pack is described and illustrated in U.S. Patent Publication No. 2019/0006980 filed Jul. 2, 2018, the entire content of which is incorporated herein by reference. In some embodiments, the battery cells  68  have a nominal voltage of up to about 80 V. In some embodiments, the battery cells  68  have a nominal voltage of up to about 120 V. In some embodiments, the battery pack  50  has a weight of up to about 6 lb. In some embodiments, each of the battery cells  68  has a diameter of up to 21 mm and a length of up to about 71 mm. In some embodiments, the battery pack  50  includes up to twenty battery cells  68 . In some embodiments, the battery cells  68  are connected in series. In some embodiments, the battery cells  68  are operable to output a sustained operating discharge current of between about: 20 A and 60 A, 20 A and 50 A, 30 A and 50 A, 20 A and 40 A, or 40 A and 60 A. In some embodiments, each of the battery cells  68  has a capacity of between about 3.0 Ah and about 5.0 Ah. 
     Although various concepts are described herein as they apply to a gas engine replacement device, in some embodiments, these concepts may be applied to other application where a motor is not the load. For example, the load may be a lighting system powered by the battery pack  50 . 
       FIG. 6  illustrates the battery receptacle  54  of the gas engine replacement device  10  in accordance with some embodiments. The battery receptacle  54  includes the projection/recess  74 , a second terminal  78 , a latching mechanism  82 , and a power disconnect switch  86 . The projection/recess  74  cooperates with the projection/recess  70  of the battery pack  50  to attach the battery pack  50  to the battery receptacle  54  of the gas engine replacement device  10 . When the battery pack  50  is attached to the gas engine replacement device  10 , the second terminal  78  and the first terminal  66  are electrically connected to each other. The latching mechanism  82  protrudes from a surface of the battery receptacle  54  and is configured to engage the battery pack  50  to maintain engagement between the battery pack  50  and the battery receptacle  54 . Thus, the battery pack  50  is connectable to and supportable by the battery receptacle  54  such that the battery pack  50  is supportable by the housing  14  of the gas engine replacement device  10 . In some embodiments, the battery pack receptacle  54  is arranged on the housing  14  in a position to create a maximum possible distance of separation between the motor  36  and the battery pack  50 , in order to inhibit vibration transferred from the motor  36  to the battery pack  50 . In some embodiments, elastomeric members are positioned on the battery pack receptacle  54  in order to inhibit vibration transferred from the motor  36 , via the housing  14 , to the battery pack  50 . 
     In other embodiments (not shown), the latching mechanism  82  may be disposed at various locations (e.g., on a sidewall, an end wall, an upper end wall etc., of the battery receptacle  54 ) such that the latching mechanism  82  engages corresponding structure on the battery pack  50  to maintain engagement between the battery pack  50  and the battery receptacle  54 . The latching mechanism  82  includes a pivotable actuator or handle  90  operatively engaging a latch member  94 . The latch member  94  is slidably disposed in a bore  99  of the battery pack receptacle  54  and is biased toward a latching position by a biasing member  103  (e.g., a spring) to protrude through a surface of the battery receptacle  54  and into a cavity in the battery pack  50 . 
     The latching mechanism also  82  includes the power disconnect switch  86  (e.g., a micro-switch) facilitating electrical connecting/disconnecting the battery pack  50  from the battery receptacle  54  during actuation of the handle  90  to withdraw the latch member  94  from the battery pack  50 . The power disconnect switch  86  may act to electrically disconnect the battery pack  50  from the gas engine replacement device  10  prior to removal of the battery pack  50  from the battery receptacle  54 . The power disconnect switch  86  is actuated when the latch member  94  is moved from the latched position (i.e., when the latch member  94  is completely within the cavity of the battery pack  50 ) to an intermediate position. The power disconnect switch  86  is electrically connected to the controller  46  and may generate an interrupt to indicate that the battery pack  50  is being disconnected from the gas engine replacement device  10 . When the controller  46  receives the interrupt, the controller  46  begins a power down operation to safely power down the control electronics  42  of the gas engine replacement device  10 . A similar latching mechanism and disconnect switch is described and illustrated in U.S. Patent Publication No. 2019/0006980, which has been incorporated herein by reference. 
     As shown in  FIG. 7 , the motor  36  includes a motor housing  96  having an outer diameter  97 , a stator  98  having a nominal outer diameter  101  of up to about 80 mm, a rotor  102  having an output shaft  106  and supported for rotation within the stator  98 , and a fan  108 . A similar motor is described and illustrated in U.S. Patent Publication No. 2019/0006980, which has been incorporated herein by reference. In some embodiments, the motor  36  is a brushless direct current motor. In some embodiments, the motor  36  has a power output of at least about 2760 W. In some embodiments, the power output of the motor  36  may drop below 2760 W during operation. In some embodiments, the fan  108  has a diameter  109  that is larger diameter  97  of the motor housing  96 . In some embodiments, the motor  36  can be stopped with an electronic clutch (not shown) for quick overload control. In some embodiments, the motor  36  has a volume of up to about 443,619 mm 3 . In some embodiments, the motor has a weight of up to about 4.6 lb. The housing  14  includes an inlet vent and an outlet vent, such that the motor fan  108  pulls air through the inlet vent and along the control electronics  42  to cool the control electronics  42 , before the air is exhausted through the outlet vent. In the embodiment illustrated in  FIG. 7 , the motor  36  is an internal rotor motor, but in other embodiments, the motor  36  can be an outer rotor motor with a nominal outer diameter (i.e. the nominal outer diameter of the rotor) of up to about 80 mm. In some embodiments, the motor has a nominal outer diameter above 80 mm, for example, up to 90 mm, 100 mm, 110 mm, 120 mm, or 125 mm. 
     With reference to  FIG. 8 , the motor  36  can transfer torque to the power take-off shaft  38  in a variety of configurations. In some embodiments, the output shaft  106  is also the power take-off shaft  38 , such that the motor  36  directly drives the power take-off shaft  38  without any intermediate gear train. For example, the motor  36  may be a direct drive high pole count motor. As shown in  FIG. 8 , in other embodiments, the gas engine replacement device  10  includes a gear train  110  that transfers torque from the motor  36  to the power take-off shaft  38 . In some embodiments, the gear train  110  can include a mechanical clutch (not shown) to discontinue the transfer of torque from the motor  36  to the power take-off shaft  38 . In some embodiments, the gear train  110  may include a planetary transmission that transfers torque from the output shaft  106  to the power take-off shaft  38 , and a rotational axis of the output shaft  106  is coaxial with a rotational axis of the power take-off shaft  38 . In some embodiments, the gear train  110  includes a spur gear engaged with the output shaft  106  of the rotor, such that the rotational axis of the output shaft  106  is offset from and parallel to the rotational axis of the power take-off shaft  38 . In some embodiments, the gear train  110  includes a bevel gear, such that the rotational axis of the output shaft  106  is perpendicular to the rotational axis of the power take-off shaft  38 . In other embodiments utilizing a bevel gear, the rotational axis of the output shaft  106  is not perpendicular, parallel, or coaxial to the rotational axis of the power take-off shaft  38 , and the power take-off shaft  38  protrudes from the flange  34 . 
     In some embodiments, the gas engine replacement device  10  includes ON/OFF indicators (not shown). In some embodiments, the gas engine replacement device  10  includes a filter (not shown) to keep airborne debris out of the motor  36  and control electronics  42 . In some embodiments, the filter includes a dirty filter sensor (not shown) and a self-cleaning mechanism (not shown). In some embodiments, the motor  36  will mimic a gas engine response when encountering resistance, such as slowing down or bogging. In some embodiments, the gas engine replacement device  10  includes a heat sink  202  in the housing  14  for air-cooling the control electronics  42  ( FIGS. 1 and 2 ). In some embodiments, the gas engine replacement device  10  is liquid cooled. 
     In some embodiments, the output shaft  106  of the rotor  102  has both forward and reverse capability as further described below. In some embodiments, the forward and reverse capability is controllable without shifting gears of the gear train  110 , in comparison to gas engines, which cannot achieve forward/reverse capability without extra gearing and time delay. Thus, the gas engine replacement device  10  provides increased speed, lower weight, and lower cost. Because the gas engine replacement device  10  has fewer moving parts and no combustion system, as compared with a gas engine, it also provides additional speed, weight, and cost advantages. 
     The gas engine replacement device  10  is able to operate in any orientation (vertical, horizontal, upside down) with respect to a ground surface for a prolonged period of time, giving it an advantage over four-cycle gas engines, which can only be operated in one orientation and at slight inclines for a shorter period of time. Because the gas engine replacement device  10  does not require gas, oil, or other fluids, it can run, be transported, and be stored upside down or on any given side without leaking or flooding 
     In operation, the gas engine replacement device  10  can be used to replace a gas engine system. Specifically, the gas engine replacement device  10  can be mounted to the piece of power equipment having a second bolt pattern by aligning a first bolt pattern defined by the plurality of apertures in the flange  34  with the second bolt pattern. In some embodiments, the flange  34  may include one or more intermediate mounting members or adapters arranged between the flange  34  itself and the flange of the piece of power equipment having the second bolt pattern, such that the adapter(s) couple the flange  34  to the piece of power equipment. In these embodiments, the adapter includes both the second bolt pattern and the first bolt pattern, such that the first bolt pattern of the flange  34  aligns with the first bolt pattern of the adapter and the second bolt pattern of the adapter aligns with the second bolt pattern defined in the piece of power equipment, thereby allowing the flange  34  of the gas engine replacement device  10  to be coupled to the piece of power equipment. 
     Alternatively, the gas engine replacement device  10  can be connected to a piece of power equipment using a belt system by providing a belt that operatively connects the power take-off shaft and an equipment bit. Thus, the power take-off shaft  38  of the gas engine replacement device  10  can be used to drive the equipment. 
     During operation, the housing  14  of the gas engine replacement device  10  is comparably much cooler than the housing of an internal combustion unit because there is no combustion in the gas engine replacement device  10 . Specifically, when a gas engine unit runs, the housing of the gas engine unit is 220 degrees Celsius or higher. In contrast, when the gas engine replacement device  10  runs, all of the exterior surfaces of the housing  14  are less than 95 degrees Celsius. Tables 1 and 2 below list with further specificity the temperature limits of different components on the housing  14  of the gas engine replacement device  10 . 
     Table 1 below lists the Underwriter&#39;s Laboratories (UL) temperature limits of different components typically used in power tools, with respect to whether those components are formed of metal, plastic, rubber, wood, porcelain, or vitreous. For example, at least in some embodiments, the plastic rated temperatures are never exceeded by the gas engine replacement device  10 . 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Plastic/ 
                 Porcelain/ 
               
               
                   
                 Metal 
                 Rubber/Wood 
                 Vitreous 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Casual Contact 
                 85° C. 
                 85° C. 
                 85° C. 
               
               
                 Handles and knobs that are 
                 55° C. 
                 75° C. 
                 65° C. 
               
               
                 continuously held 
               
               
                 Handles and knobs that are 
                 60° C. 
                 80° C. 
                 70° C. 
               
               
                 only briefly held (i.e. switches) 
               
               
                   
               
            
           
         
       
     
     Table 2 below lists the UL temperature limits of different components of the battery pack housing  58  of the battery pack  50 , with respect to whether those components are formed of metal, plastic or rubber. For example, at least in some embodiments, the plastic rated temperatures are never exceeded by the gas engine replacement device  10 . 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Metal 
                 Plastic/Rubber 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Casual Contact 
                 70° C. 
                 95° C. 
               
               
                 Handles and knobs that are continuously held 
                 55° C. 
                 75° C. 
               
               
                 Handles and knobs that are only briefly held 
                 60° C. 
                 85° C. 
               
               
                 (i.e. switches) 
               
               
                   
               
            
           
         
       
     
       FIG. 9  illustrates a simplified block diagram of the gas engine replacement device  10  according to one example embodiment. As shown in  FIG. 9 , the gas engine replacement device  10  includes an electronic processor  302 , a memory  306 , the battery pack  50 , a power switching network  310 , the motor  36 , a rotor position sensor  314 , a current sensor  318 , a user input device  322  (e.g., a throttle, trigger, or power button), a transceiver  326 , indicators  330  (e.g., light-emitting diodes), and a vibration sensor  320 . In some embodiments, the gas engine replacement device  10  includes fewer or additional components than those shown in  FIG. 9 . For example, the gas engine replacement device  10  may include a battery pack fuel gauge, work lights, additional sensors, kill switch, the power disconnect switch  86 , etc. In some embodiments, elements of the gas engine replacement device  10  illustrated in  FIG. 9  including one or more of the electronic processor  302 , memory  306 , power switching network  310 , rotor position sensor  314 , current sensor  318 , user input device  322 , transceiver  326 , indicators  330 , and vibration sensor  320  form at least part of the control electronics  42  shown in  FIG. 3 , with the electronic processor  302  and the memory  306  forming at least part of the controller  46  shown in  FIG. 3 . 
     The memory  306  includes read only memory (ROM), random access memory (RAM), other non-transitory computer-readable media, or a combination thereof. The electronic processor  302  is configured to communicate with the memory  306  to store data and retrieve stored data. The electronic processor  302  is configured to receive instructions and data from the memory  306  and execute, among other things, the instructions. In particular, the electronic processor  302  executes instructions stored in the memory  306  to perform the methods described herein. 
     As described above, in some embodiments, the battery pack  50  is removably connected to the housing of the gas engine replacement device  10  such that a different battery pack  50  may be attached and removed to the gas engine replacement device  10  to provide different amount of power to the gas engine replacement device  10 . Further description of the battery pack  50  (e.g., nominal voltage, sustained operating discharge current, size, number of cells, operation, and the like), as well as the motor  36  (e.g., power output, size, operation, and the like), is provided above with respect to  FIGS. 1-8 . 
     The power switching network  310  enables the electronic processor  302  to control the operation of the motor  36 . Generally, when the user input device  322  is depressed (or otherwise actuated), electrical current is supplied from the battery pack  50  to the motor  36 , via the power switching network  310 . When the user input device  322  is not depressed (or otherwise actuated), electrical current is not supplied from the battery pack  50  to the motor  36 . In some embodiments, the amount in which the user input device  322  is depressed is related to or corresponds to a desired speed of rotation of the motor  36 . In other embodiments, the amount in which the user input device  322  is depressed is related to or corresponds to a desired torque. In other embodiments, a separate input device (e.g., slider, dial, or the like) is included on the gas engine replacement device  10  in communication with the electronic processor  302  to provide a desired speed of rotation or torque for the motor  36 . 
     In response to the electronic processor  302  receiving a drive request signal from the user input device  322 , the electronic processor  302  activates the power switching network  310  to provide power to the motor  36 . Through the power switching network  310 , the electronic processor  302  controls the amount of current available to the motor  36  and thereby controls the speed and torque output of the motor  36 . The power switching network  310  may include numerous field-effect transistors (FETs), bipolar transistors, or other types of electrical switches. For instance, the power switching network  310  may include a six-FET bridge (see  FIG. 10 ) that receives pulse-width modulated (PWM) signals from the electronic processor  302  to drive the motor  36 . 
     The rotor position sensor  314  and the current sensor  318  are coupled to the electronic processor  302  and communicate to the electronic processor  302  various control signals indicative of different parameters of the gas engine replacement device  10  or the motor  36 . In some embodiments, the rotor position sensor  314  includes a Hall sensor or a plurality of Hall sensors. In other embodiments, the rotor position sensor  314  includes a quadrature encoder attached to the motor  36 . The rotor position sensor  314  outputs motor feedback information to the electronic processor  302 , such as an indication (e.g., a pulse) when a magnet of a rotor of the motor  36  rotates across the face of a Hall sensor. In yet other embodiments, the rotor position sensor  314  includes, for example, a voltage or a current sensor that provides an indication of a back electro-motive force (back emf) generated in the motor coils. The electronic processor  302  may determine the rotor position, the rotor speed, and the rotor acceleration based on the back emf signals received from the rotor position sensor  314 , that is, the voltage or the current sensor. The rotor position sensor  314  can be combined with the current sensor  318  to form a combined current and rotor position sensor. In this example, the combined sensor provides a current flowing to the active phase coil(s) of the motor  36  and also provides a current in one or more of the inactive phase coil(s) of the motor  36 . The electronic processor  302  measures the current flowing to the motor based on the current flowing to the active phase coils and measures the motor speed based on the current in the inactive phase coils. 
     Based on the motor feedback information from the rotor position sensor  314 , the electronic processor  302  can determine the position, velocity, and acceleration of the rotor. In response to the motor feedback information and the signals from the user input device  322 , the electronic processor  302  transmits control signals to control the power switching network  310  to drive the motor  36 . For instance, by selectively enabling and disabling the FETs of the power switching network  310 , power received from the battery pack  50  is selectively applied to stator windings of the motor  36  in a cyclic manner to cause rotation of the rotor of the motor  36 . The motor feedback information is used by the electronic processor  302  to ensure proper timing of control signals to the power switching network  310  and, in some instances, to provide closed-loop feedback to control the speed of the motor  36  to be at a desired level. For example, to drive the motor  36 , using the motor positioning information from the rotor position sensor  314 , the electronic processor  302  determines where the rotor magnets are in relation to the stator windings and (a) energizes a next stator winding pair (or pairs) in the predetermined pattern to provide magnetic force to the rotor magnets in a direction of desired rotation, and (b) de-energizes the previously energized stator winding pair (or pairs) to prevent application of magnetic forces on the rotor magnets that are opposite the direction of rotation of the rotor. 
     The current sensor  318  monitors or detects a current level of the motor  36  during operation of the gas engine replacement device  10  and provides control signals to the electronic processor  302  that are indicative of the detected current level. The electronic processor  302  may use the detected current level to control the power switching network  310  as explained in greater detail below. 
     The transceiver  326  allows for communication between the electronic processor  302  and an external device  338  (e.g., a smart phone, tablet, or laptop computer) over a wired or wireless communication network  334 . In some embodiments, the transceiver  326  may comprise separate transmitting and receiving components. In some embodiments, the transceiver  326  may comprise a wireless adapter attached to the gas engine replacement device  10 . In some embodiments, the transceiver  326  is a wireless transceiver that encodes information received from the electronic processor  302  into a carrier wireless signal and transmits the encoded wireless signal to the external device  338  over the communication network  334 . The transceiver  326  also decodes information from a wireless signal received from the external device  338  over the communication network  334  and provides the decoded information to the electronic processor  302 . In some embodiments, the transceiver  326  communicates with one or more external sensors  340  via the communication network  334 . For example, an external sensor  340  may be associated with the equipment to which the gas engine replacement device  10  is mounted. In some embodiments, the external sensor  340  is a speed sensor, a position sensor, or the like. In some embodiments, the battery pack  50  includes a transceiver. In some embodiments, the battery pack transceiver communicates wirelessly with the transceiver  326  in the power tool  10  or with the external device  338 . In some embodiments, the external device  338  communicates data, such as the battery pack configuration data, to the power tool  10 . For example, the transceiver in the battery pack  50  may communicate the battery pack configuration data to the external device  338 , and the external device  338  may communicate the battery pack configuration data to the transceiver  326  in the power tool  10 . 
     The communication network  334  provides a wired or wireless connection between the gas engine replacement device  10 , the external device  338 , and the external sensor  340 . The communication network  334  may comprise a short range network, for example, a BLUETOOTH network, a Wi-Fi network or the like, or a long range network, for example, the Internet, a cellular network, or the like. 
     As shown in  FIG. 9 , the indicators  330  are also coupled to the electronic processor  302  and receive control signals from the electronic processor  302  to turn on and off or otherwise convey information based on different states of the gas engine replacement device  10 . The indicators  330  include, for example, one or more light-emitting diodes (“LEDs”), or a display screen. The indicators  330  can be configured to display conditions of, or information associated with, the gas engine replacement device  10 . For example, the indicators  330  are configured to indicate measured electrical characteristics of the gas engine replacement device  10 , the status of the gas engine replacement device  10 , the mode of the gas engine replacement device  10 , etc. The indicators  330  may also include elements to convey information to a user through audible or tactile outputs. In some embodiments, the indicators  330  include an eco-indicator that indicates an amount of power being used by the load during operation. 
     The connections shown between components of the gas engine replacement device  10  are simplified in  FIG. 9 . In practice, the wiring of the gas engine replacement device  10  is more complex, as the components of a gas engine replacement device are interconnected by several wires for power and control signals. For instance, each FET of the power switching network  310  is separately connected to the electronic processor  302  by a control line; each FET of the power switching network  310  is connected to a terminal of the motor  36 ; the power line from the battery pack  50  to the power switching network  310  includes a positive wire and a negative/ground wire; etc. Additionally, the power wires can have a large gauge/diameter to handle increased current. Further, although not shown, additional control signal and power lines are used to interconnect additional components of the gas engine replacement device  10 . 
     In some embodiments, the battery pack  50  includes an electronic processor  336 , a memory  339 , and one or more battery sensors  341 . The memory  339  includes read only memory (ROM), random access memory (RAM), other non-transitory computer-readable media, or a combination thereof. The electronic processor  336  is configured to communicate with the memory  339  to store data and retrieve stored data. The electronic processor  336  is configured to receive instructions and data from the memory  339  and execute, among other things, the instructions. In particular, the electronic processor  336  executes instructions stored in the memory  339  to perform battery control functions described herein. The battery sensors  341  provide information associated with the battery pack  50 , such as temperature, stage of charge, discharge rate, and the like. The sensors  341  may provide the information to the electronic processor  336 , which may, for example, store the sensor data in the memory  339 , analyze the information and take responsive action, or both. In some embodiments, the memory  339  stores battery configuration data, such as a maximum discharge current, an age parameter (e.g., manufacturer date or number of charge/discharge cycles), and the like. In some embodiments, the battery configuration data can be determined non-digitally, such as by reading or determining a value for capacitance, resistance, inductance, magnetic field strength, etc., associated with the battery pack  50  which can be determined by the gas engine replacement device  10 . 
     The electronic processor  336  in the battery pack  50  communicates with the electronic processor  302  in the gas engine replacement device  10  to exchange configuration data and status data associated with the battery pack  50 . In some embodiments, the configuration data includes the maximum discharge current associated with the battery pack. In some embodiments, the electronic processor  336  also communicates status data associated with the battery pack  50  to the electronic processor  302 , such as age, state of charge, discharge rate, and the like. The electronic processor  336  in the battery pack  50  may communicate with the electronic processor  302  in the gas engine replacement device through a wired or wireless interface. 
     The battery pack  50  has a particular arrangement of cells that affects its power supply capabilities. Different cell types can provide different current levels at a recommended operating temperature. For example, a “30T” cell might be able to discharge continuously at 30 A in the battery pack  50  with a certain airflow design that reaches thermal equilibrium at a temperature below the maximum allowed temperature of the battery pack  50 . A “40T” cell might only be able to be discharged in a similar design at 25 A. If the gas engine replacement device  10  is optimized for 30 A discharge, it could cause an over-temp condition in the battery pack  50  with a “40T” in a similar use case without discharging all available energy within the cells. If an over-temp condition is reached, the electronic processor  336  in the battery pack  50  would signal a fault condition and interrupt power until the battery pack  50  cooled down to an acceptable temperature before remaining charge in the battery pack  50  could be accessed. Alternatively, if the gas engine replacement device  10  is optimized for a 25 A discharge, the gas engine replacement device  10  would operate at a lower, and potentially less preferred operating load point, which could result in the functions of the gas engine replacement device  10  being completed at a slower rate or less efficiently. 
       FIG. 10  is a flowchart of an example method  400  for battery pack configuration control in the gas engine replacement device  10  of  FIG. 1 . Connection or insertion of the battery pack  50  is detected at block  405 . In some embodiments, the electronic processor  336  in the battery pack  50  detects the connection of the battery pack  50 , while in other embodiments, the electronic processor  302  in the gas engine replacement device  10  detects the connection of the battery pack  50 . In some embodiments, connection of the battery pack  50  is detected by the electronic processor  336  or the electronic processor  302  ( a ) using a wired communication from the other of the electronic processor  336  and the electronic processor  302  or (b) a hardware detection circuit that detects or measures changes in resistance or voltage (e.g., at the terminal  66  or  78 ) above a certain threshold and provides a signal to the electronic processor  336  or the electronic processor  302 . 
     Battery pack configuration data is communicated to the gas engine replacement device  10  at block  410 . In some embodiments, the electronic processor  336  in the battery pack  50  broadcasts the battery pack configuration data responsive to detecting the connection at block  405 . In some embodiments, the electronic processor  302  in the gas engine replacement device  10  polls the battery pack  50  to retrieve the battery pack configuration data responsive to detecting the insertion of the battery pack  50  at block  405 . In some embodiments, the electronic processor  302  in the gas engine replacement device  10  reads the battery pack configuration data directly from the memory  339  in the battery pack  50 . In an embodiment where the electronic processor  302  in the gas engine replacement device  10  reads the battery pack configuration data directly from the memory  339  in the battery pack  50 , the electronic processor  336  in the battery pack  50  may be omitted. In some embodiments, one or more of the battery pack configuration data parameters may be measured or inferred. For example, a technique that includes pulsing a current and measuring a voltage drop or resistance in the battery pack  50  in response to the pulse may be employed to measure a battery pack configuration parameter. 
     Upon receipt, the gas engine replacement device  10  stores the battery pack configuration data in the memory  306 . In some embodiments, the battery pack configuration data includes parameters such as cell size, cell maximum temperature, maximum discharge current, minimum operating speed, and the like. The battery pack configuration data may be written to the memory  339  of the battery pack  50  at the time of manufacturing or rewritten during regular service or calibration intervals by a certified service center. In some embodiments, the maximum discharge current represents the maximum current the battery pack  50  can provide until complete discharge with no thermal overload occurring. 
     In block  412 , the electronic processor  302  of the gas engine replacement device  10  operates the motor  36  according to the battery pack configuration data received from the battery pack  50 . For example, the electronic processor  302  can control the motor  36  using a motor control algorithm that considers the maximum discharge current to ensure the current drawn from the battery pack  50  does not exceed the specified maximum discharge current. In some embodiments, the current sensor  318  measures a current parameter, such as a motor current, and is employed by the electronic processor  302  to estimate the discharge current. In some embodiments, the current sensor  318  directly monitors current drawn from the battery pack  50  as the current parameter. In some embodiments, the battery sensor  341  measures the battery current as the current parameter. In some embodiments, the motor current is measured indirectly by measuring motor back emf signals, such as from the output of the rotor position sensor  314 , or by measuring voltage drops across the motor  36 . 
     In some embodiments, the electronic processor  302  may initialize the motor control algorithm by operating the motor at 100% PWM (i.e., controlling switches of the power switching network  310  using control signals having 100% PWM duty cycle) while monitoring the current drawn from the battery pack  50  compared to the maximum discharge current specified in the battery pack configuration data. If the current from the battery pack  50  reaches the maximum discharge current, the electronic processor  302  can reduce the PWM parameter, reducing the current being consumed compared to 100% PWM operation. The electronic processor  302  can continue to lower the PWM parameter until a minimum device operation setting, or 0% PWM was reached. In this manner, the electronic processor  302  can generate an operating curve that relates the PWM parameter to current draw under the current ambient environment of the gas engine replacement device  10 . In some embodiments, the electronic processor  302  stores a PWM parameter upper limit in the memory  306  that is determined based on the maximum discharge current. The electronic processor  302  may control the operation of the gas engine replacement device  10  based on the PWM parameter upper limit without continuous monitoring the current drawn from the battery pack  50 . In some embodiments, the electronic processor  302  may continuously monitor the current drawn from the battery pack  50 , compare the current measured to the maximum discharge current, and reduce the PWM parameter, such as the duty cycle of the signals driving the power switching network  310 , in response to the current exceeding the maximum discharge current. 
     In some embodiments, the control algorithm used by the electronic processor  302  in the gas engine replacement device  10  may employ predetermined operating parameters, such as a PWM parameter upper limit, that are defined as a function of the battery pack configuration data, such as cell size, cell maximum temperature, maximum discharge current, discharge state, and the like. For example, a look-up table mapping various battery pack configuration data to associated PWM limits may be employed. 
     In some embodiments, the method  400  ends at block  412  and the remaining steps are not executed. In other embodiments, the method proceeds to block  415 . 
     At block  415 , the electronic processor  336  in the battery pack  50  monitors the battery pack condition. In some embodiments, the battery pack condition includes a temperature parameter. In some embodiments, the battery pack condition includes a capacity rate of change of the battery pack or power usage by the gas engine replacement device  10 . The maximum discharge current associated with the battery pack  50  is generally set based on certain assumptions regarding the thermal conditions of the battery pack  50  during operations, such as the air flow design for cooling the battery pack  50 . Under certain conditions, the cooling may be compromised, or the ambient temperature may be increased such that the actual operating conditions differ from the assumptions. As a result, the temperature of the battery pack  50  may approach a fault threshold even if the maximum discharge current is not exceeded by the gas engine replacement device  10 . In some embodiments, the maximum discharge current may be set based on an assumed discharge rate for the battery pack  50 . For example, the battery pack  50  may be assumed to be able to deliver power at the maximum discharge current for a known time period, thereby defining a discharge rate. The actual rate that the battery charge discharges may differ based on conditions, such as the temperature or other factors. In some embodiments, the electronic processor  336  in the battery pack  50  monitors the battery pack discharge rate as the battery pack condition. 
     The electronic processor  336  in the battery pack  50  determines whether a condition of the battery pack  50  violates a threshold at block  420 . For example, a temperature of the battery pack  50  measured by the battery sensors  341  may exceed a threshold, or the battery pack depletion rate may exceed a threshold. In some embodiments, the threshold is set at a level less than a fault threshold that would result in a power interruption. 
     If the threshold is violated at block  420 , the electronic processor  336  in the battery pack  50  revises the battery pack configuration data. For example, the maximum discharge current of the battery pack  50  may be reduced. In an embodiment where the electronic processor  336  in the battery pack  50  is omitted, the electronic processor  302  in the gas engine replacement device  10  may receive data from the battery sensor  341 , determine whether the condition of the battery pack  50  violates the threshold at block  420 , and revise the battery pack configuration data. 
     The revised battery pack configuration data is communicated to the gas engine replacement device  10  at block  425 . In some embodiments, the electronic processor  336  in the battery pack  50  pushes the revised battery pack configuration data to the electronic processor  302  in the gas engine replacement device  10 . In some embodiments, the electronic processor  302  in the gas engine replacement device  10  polls the battery pack  50  at regular intervals or between operating cycles to identify any changes to the battery pack configuration data. In an embodiment where the electronic processor  336  in the battery pack  50  is omitted, the electronic processor  302  revises the battery pack configuration data. 
     In some embodiments, upon receiving the revised battery pack configuration data, the electronic processor  302  stores the revised battery pack configuration data (e.g., updated or overwriting the previous battery pack configuration data) in the memory  306 , and thereby revising its control algorithm. For example, a revised maximum discharge current may be stored in the memory  306 . In some embodiments, the PWM initialization routing described above may be repeated to generate a new PWM limit or the look-up table may be accessed based on the revised battery pack configuration data. At a later point in time, such as after a temperature of the battery pack  50  has been reduced to a lower level, the electronic processor  336  in the battery pack  50  may again revise the battery pack configuration data to increase the maximum discharge current. In this manner, the maximum discharge current associated with the battery pack  50  may be dynamically controlled based on the actual operating environment of the gas engine replacement device  10 . 
     The method then returns to block  412 , where the electronic processor  302  operates the motor according to the battery pack configuration data as revised at block  425  (i.e., according to the revised battery pack configuration data). 
     The mechanical systems described above driven by the gas engine replacement device  10  includes many advantages over conventional equipment driven by an internal combustion engine, some of which are discussed below. 
     In some embodiments, the gas engine replacement device  10  can be mated with a new equipment and the memory  306  can be reprogrammed to optimize the gas engine replacement device  10  for operation with the new equipment. In some embodiments, the electronic processor  302  automatically recognizes which type of new equipment the gas engine replacement device  10  has been mated with, and governs operation of the gas engine replacement device  10  accordingly. In some embodiments, the electronic processor  302  can automatically detect with which equipment the gas engine replacement device  10  has been mated via Radio Frequency Identification (RFID) communication with the new equipment. 
     In some embodiments, the memory  306  is reprogrammable via either BLUETOOTH or Wi-Fi communication protocols. In some embodiments, the electronic processor  302  has control modes for different uses of the same equipment. The control modes may be preset or user-programmable, and may be programmed remotely via BLUETOOTH or Wi-Fi. In some embodiments, the electronic processor  302  utilizes master/slave equipment-to-equipment communication and coordination, such that the gas engine replacement device  10  can exert unidirectional control over equipment, or an operator can use a smartphone application to exert unidirectional control over the gas engine replacement device  10 . 
     In some embodiments, the operator or original equipment manufacturer (OEM) is allowed limited access to control the speed of the gas engine replacement device  10  through the electronic processor  302  via, e.g., a controller area network (CAN)-like interface. In some embodiments, the electronic processor  302  is capable of a wider range of speed selection with a single gear set in the gear train  110  than a gasoline engine. For example, the control electronics  42  are configured to drive the motor  36  at less than 2,000 RPM, which is lower than any speed a gasoline engine is capable of, which permits the associated equipment to have a greater overall runtime over a full discharge of the battery pack  50 , than a gasoline engine. Additionally the control electronics  42  are configured to drive the motor at more than 3,600 RPM, which is higher than any speed a gasoline engine is capable of, and with the capability to deliver more torque. The wider range of speeds of motor  36  offers greater efficiency and capability than a gasoline engine. In some embodiments, the operator could have access to control the current drawn by the motor  36  in addition to the speed. 
     In some embodiments, the electronic processor  302  is configured to log and report data. For example, the electronic processor  302  is configured to provide wired or wireless diagnostics for monitoring and reading the status of the gas engine replacement device  10 . For example, the electronic processor  302  can monitor and log gas engine replacement device  10  runtime for example, in a rental scenario. In some embodiments, the motor  36  and the electronic processor  302  use regenerative braking to charge the battery pack  50 . In some embodiments, the gas engine replacement device  10  includes a DC output for lights or accessories. In some embodiments, the electronic processor  302  can detect anomalies or malfunctions of the gas engine replacement device  10  via voltage, current, motion, speed, and/or thermocouples. In some embodiments, the electronic processor  302  can detect unintended use of or stoppage of the gas engine replacement device  10 . If the equipment driven by the gas engine replacement device  10  is not running with the intended characteristics or is not being used correctly or safely, the electronic processor  302  can detect the anomaly and deactivate the gas engine replacement device  10 . For example, the gas engine replacement device  10  can include one or more accelerometers to sense if the gas engine replacement device  10  and equipment is in the intended orientation. And, if the electronic processor  302  determines that the gas engine replacement device  10  is not in the intended orientation (i.e. the equipment has fallen over), the electronic processor  302  can deactivate the gas engine replacement device  10 . 
     In some embodiments, the gas engine replacement device  10  includes accessible sensor ports (not shown) to electrically connect with user-selected sensors for use with the piece of power equipment, such as accelerometers, gyroscopes, GPS units, or real time clocks, allowing an operator to customize the variables to be sensed and detected by the electronic processor  302 . In some embodiments, the electronic processor  302  can indicate the status of the battery pack  50 , such as when the battery is running low, to an operator via visual, audio, or tactile notifications. In some embodiments, the electronic processor  302  can operate an auxiliary motor that is separate from the motor  36  to drive an auxiliary device such as a winch. The auxiliary motor may be internal or external to the gas engine replacement device  10 . 
     In some embodiments, the gas engine replacement device  10  can include digital controls on a customizable user interface, such as a touch display or a combination of knobs and buttons. In contrast, an analog gasoline engine does not include such digital controls. In some embodiments, the user interface for the gas engine replacement device  10  can be modular, wired, or wireless and can be attachable to the gas engine replacement device  10  or be hand held. In some embodiments, the gas engine replacement device  10  can be controlled with a remote control that includes status indicators for certain characteristics of the gas engine replacement device  10 , such as charge of the battery pack  50  and the temperature. In some embodiments, the gas engine replacement device  10  can provide status indications with a remote, programmable device. 
       FIGS. 11 and 12  illustrates examples of power equipment driven by the gas engine replacement device  10  implementing the method  400  described above.  FIG. 11  illustrates a pump system  1100  including a frame  1102  supporting the gas engine replacement device  10  and a pump  1104  with the gas engine replacement device  10  operable to drive the pump  1104 . The illustrated pump  1104  is a centrifugal pump having an impeller positioned within a housing  1106  of the pump  1104  that is rotatable about an axis to move material from an inlet  1108  of the pump  1104  to an outlet  1110  of the pump  1104 .  FIG. 12  illustrates a mixing system  1200  including a frame  1205  supporting the gas engine replacement device  10  and a mixing drum  1210 , with the gas engine replacement device  10  operable to rotate the mixing drum  1210 .