Method of estimating a state-of-charge of a battery pack

Abstract

A method for estimating the charge state of a battery pack having one or more cells is provided. The method includes the step of obtaining data from a device electrically connected to the battery pack by a battery controller of the battery pack. The data represents the power required for the device. The method may further include the step of determining the charge state of the battery pack by the battery controller based at least partially on the data representing the power required for the device.

Description

Technology Field

[0001] The present disclosure generally relates to battery packs. More specifically, the present disclosure relates to a method for estimating the charge state of a battery pack used, for example, in power tool applications. Background Technology

[0002] Battery packs are commonly used in portable electric equipment and tools to enable easy use in environments where a fixed power source is unavailable. For example, power tool manufacturers often produce universal power packs compatible with various types of cordless power tools, such as electric drills, hammers, screwdrivers, impact wrenches, and angle grinders. Power requirements can vary depending on the power tool. For instance, the power required for a cordless drill may differ from that required for a work light. Battery packs vary in capacity and quality. Some battery packs have different output capacities depending on the type of tool connected to them.

[0003] Aspects and advantages of the embodiments of the present disclosure may be partially described in the following description, learned from the description, or learned through the practice of the embodiments.

[0004] In one embodiment, a method for estimating the charge state of a battery pack having one or more cells is provided. The method comprises the step of obtaining data from a device electrically connected to the battery pack by a battery controller of the battery pack. The data represents the power required for the device. The method further comprises the step of determining the charge state of the battery pack by the battery controller based at least partially on the data representing the power required for the device.

[0005] In another embodiment, a battery pack is provided. The battery pack comprises one or more battery cells. The battery pack further comprises a controller. The controller is configured to acquire data from a device electrically connected to one or more battery cells. The data represents the power required for the device. The controller is further configured to determine the charge state of the battery pack based at least partially on the data representing the power required for the device.

[0006] In another embodiment, a power tool is provided. The power tool includes an electric motor and a controller. The controller is configured to acquire data from a battery pack electrically connected to power. The data represents the impedance of the battery pack. The controller is configured to determine a regulated amount of power that the electric motor draws from the battery pack based at least partially on the data representing the impedance of the battery pack. The controller is further configured to control the operation of the electric motor so that the electric motor draws a regulated amount of power from the battery pack.

[0007] These features, aspects, and advantages of the various embodiments, and other features, aspects, and advantages, will be better understood by referring to the following description and the appended claims. The accompanying drawings, which are included in and constitute part of this specification, are intended to illustrate embodiments of the disclosure and to explain the relevant principles together with the detailed description. Brief explanation of the drawing

[0008] Detailed descriptions of embodiments for those skilled in the art are provided in the specification with reference to the attached drawings. FIG. 1 illustrates a schematic diagram of a power tool according to an exemplary embodiment of the present disclosure. FIG. 2 illustrates a schematic diagram of a battery pack according to an exemplary embodiment of the present disclosure. FIG. 3 illustrates a battery pack electrically connected to a device according to an exemplary embodiment of the present disclosure. FIG. 4 illustrates a flowchart of a method for estimating the charge state of a battery pack according to an exemplary embodiment of the present disclosure. FIG. 5 illustrates a graph of the capacity of a battery pack for various devices according to an exemplary embodiment of the present disclosure. FIG. 6 illustrates a flowchart of a method for operating a power tool according to an exemplary embodiment of the present disclosure. Specific details for implementing the invention

[0009] Now, reference will be made to the embodiments in detail, one or more of which are illustrated in the drawings. Each example is provided to illustrate the embodiments and not to limit the scope of the disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the embodiments without departing from the scope or spirit of the disclosure. For example, features illustrated or described as part of one embodiment may be used in combination with another embodiment to create yet another embodiment. Accordingly, aspects of the disclosure are intended to include such modifications and variations.

[0010] An exemplary aspect of the present disclosure relates to a battery pack and a battery-driven system. A battery pack may include one or more cells. One or more cells may store and / or transfer charge (e.g., as power) to power a device electrically connected to the battery pack (e.g., a power tool, an electric vehicle, etc.). In some embodiments, one or more cells may include one or more lithium-ion (Li-ion) cells arranged to output direct current at the rated voltage of the battery pack. The battery pack may further include a battery controller. The battery controller may be configured to estimate the state of charge of one or more battery cells. For example, the battery controller may include one or more memory devices configured to store a state of charge algorithm that can be executed by the processing circuit of the battery controller (e.g., an application-specific integrated circuit (ASIC), a processor, a field-programmable gate array (FPGA), discrete logic, etc.) to cause the battery controller to estimate the state of charge of one or more battery cells.

[0011] Power consumption may vary depending on the device. For example, the power consumption of a cordless drill may be higher than that of a work light (e.g., an LED light). As such, the available capacity of the battery pack when transferring charge to the cordless drill may differ from the available capacity of the battery pack when transferring charge to the work light (e.g., it may be lower). Furthermore, since the state of charge of the battery pack is determined at least partially based on its available capacity, it can be said that the estimated state of charge of the battery pack when transferring charge to the cordless drill differs from the estimated state of charge of the battery pack when transferring charge to the work light (e.g., it may be smaller).

[0012] Conventional battery controllers may attempt to estimate the charge state of a battery pack by utilizing measurements or foreknowledge of devices electrically connected to the battery pack. However, this method is inaccurate due to variations in the power consumption of devices compatible with the battery pack. As such, the charge state estimation performed by conventional battery controllers does not account for variations in the power consumption of different devices (e.g., cordless power drills, LED lights) that can be electrically connected to the battery pack.

[0013] An exemplary aspect of the present disclosure relates to a method for determining the charge state of a battery pack. When the battery pack is electrically connected to a device, the device may provide data to a battery controller. The data may represent the power required for the device. For example, a controller associated with the device may be configured to provide data to the battery controller via a communication link (e.g., using one or more data packets). In some embodiments, the communication link may include a wired communication link. In alternative embodiments, the communication link may include a wireless communication link. It should be understood that data representing the power required for the device may be provided as input to a charge state algorithm executed by a processing circuit of the battery controller.

[0014] In some embodiments, data representing the power required for the device may include data representing one or more electrical parameters associated with the device. For example, one or more electrical parameters may include the maximum current that the device must draw to perform a task. In some embodiments, one or more electrical parameters may include the rated current for the device. In some embodiments, one or more electrical parameters may include the maximum power that the device must draw to perform a task. In some embodiments, one or more electrical parameters may include the impedance of the device (e.g., normal, minimum). However, it should be understood that one or more electrical parameters may include any appropriate parameter of the device that can be used to determine the power required for the device.

[0015] In some embodiments, data indicating the power required for the device may include data indicating the transient current that the device initially draws when performing a task. For example, the device may be a cordless power drill, and the task may include drilling a hole or driving a fastener (e.g., a screw). In such embodiments, the data may indicate the transient current (e.g., about 40 A) that the electric motor of the cordless power drill initially draws to enable the cordless power drill to perform the task.

[0016] In some embodiments, data representing the power required for the device may include a current profile for the device. For example, the current profile may include data representing the current drawn by the device over time. In alternative embodiments, data representing the power required for the device may include a power profile for the device. For example, the power profile may include data representing the power drawn by the device over time.

[0017] In some embodiments, data indicating the power required for a device may include data indicating a model number associated with the device. For example, the device may be a cordless power tool, and the data indicating the power required for the device may include data indicating a model number associated with the cordless power tool. In such embodiments, the battery controller may be configured to store a lookup table or other data structure containing power requirements and model numbers for a plurality of different power tools (e.g., a leaf blower, a chainsaw, a shock screwdriver, etc.). For example, one or more memory devices of the battery controller may be configured to store a lookup table. The battery controller may be configured to match a model number associated with a device electrically connected to the battery pack to one of the model numbers included in the lookup table. In this way, the battery controller may determine the power required for the device based at least partially on the data indicating the model number associated with the device.

[0018] A method according to the present disclosure may include the step of determining the charge state of one or more battery cells based at least partially on data representing the power required for a device. For example, a battery controller of a battery pack may be configured to adjust the charge state of one or more battery cells from a first charge state to a second charge state based at least partially on data representing the power required for a device. In this way, the charge state of one or more battery cells may be adjusted based at least partially on the power required for a device electrically connected to the battery pack.

[0019] In some embodiments, the method according to the present disclosure may include the step of providing a notification indicating a determined charge state of one or more battery cells to be displayed on a display device. For example, in some embodiments, a battery controller may be configured to provide a notification to the device to be displayed on the display device. Alternatively or additionally, the battery controller may be configured to provide a notification to be displayed on a display device associated with a battery pack. Without departing from the scope of the present disclosure, other methods of providing a notification indicating a charge state, such as illumination of one or more indicators (e.g., LED indicators) located on the battery pack and / or device, may be used.

[0020] Exemplary embodiments of the present disclosure may provide a number of technical effects and advantages. For example, a battery controller may acquire data indicating the power required for a device electrically connected to the battery controller. Additionally, the battery controller may determine the charge state of the battery pack based at least partially on the power required. More specifically, the battery controller may adjust (e.g., increase or decrease) the charge state of the battery pack based at least partially on the power required. In this way, information indicating the charge state of the battery pack may be adjusted as needed based on different power requirements for various devices that may be electrically connected to the battery pack (e.g., power tools, LED lights, electric vehicles, etc.).

[0021] Now, referring to FIG. 1, a cordless power tool (100) according to one embodiment of the present disclosure is provided. The cordless power tool (100) comprises a housing (110) and an electric motor (112) (indicated by a dashed line) disposed within the housing (110). The electric motor (112) may be electrically connected to a battery pack (200) that is removablely connected to the housing (110) of the cordless power tool (100). In this way, the electric motor (112) may receive electrical energy from the battery pack (200). The electric motor (112) may be configured to convert electrical energy into mechanical energy required to drive the rotation of an object (e.g., a drill bit, a fastener) held by the chuck (114) of the cordless power tool (100). In some embodiments, the cordless power tool (100) may include a clutch (116). The clutch (116) may be configured to regulate the amount of torque transmitted to the object. As illustrated, the cordless power tool (100) may include an input device (118) configured to receive user input related to the operation control of the electric motor (112). For example, the input device (118) may include a trigger that a user can pull to provide user input related to starting the electric motor (112) to perform a task (e.g., drilling a hole, driving a fastener, etc.).

[0022] In some embodiments, the cordless power tool (100) may include a display device (120). The display device (120) may be configured to display information related to the operation of the battery pack (200). For example, in some embodiments, the display device (120) may display information indicating the charge status of the battery pack (200). In this way, the user can determine the charge status of the battery pack by viewing the information displayed on the display device (120) of the cordless power tool (100).

[0023] Now, referring to FIG. 2, a battery pack (200) according to an exemplary embodiment of the present disclosure is provided. As illustrated, the battery pack (200) may include a battery housing (210). The battery housing (210) may be configured to accommodate one or more battery cells (not illustrated). One or more cells may be configured to store and / or transfer charge (e.g., as power) to power a cordless power tool (100) (Fig. 1). For example, the battery housing (210) may include a terminal post (214) having terminals (216, 218). It should be understood that when the battery housing (210) is removablely connected to the cordless power tool (100), one or more battery cells may be electrically connected to an electric motor (112).

[0024] FIGS. 1 and 2 illustrate examples of power tools and battery packs for example and discussion. Those skilled in the art will understand, by utilizing the disclosures provided herein, that a battery pack may be used to deliver power to devices other than cordless power tools (e.g., drills, leaf blowers, etc.). For example, in some embodiments, the battery pack (200) may be used to deliver power to a light-emitting diode (LED) light.

[0025] Now, referring to FIG. 3, a battery pack (300) electrically connected to the device (400) is provided according to an exemplary embodiment. In this way, the battery pack (300) can deliver power to the device (400), particularly to the load (410) of the device. In some embodiments, the device (400) may be a cordless power tool, such as the cordless power tool (100) described above with reference to FIG. 1. However, it should be understood that the device (400) may include any device having one or more loads configured to receive power from the battery pack (300). For example, in some embodiments, the device (400) may be an electric vehicle. In alternative embodiments, the device (400) may include a light-emitting diode (LED) light.

[0026] As illustrated, the battery pack (300) may include one or more battery cells (310). One or more battery cells (310) may be configured to store and / or transfer charge (e.g., as power) to the device (400) through one or more conductors (312). In some embodiments, the load (410) of the device (400) may be an electric motor. In alternative embodiments, the load (410) may be a power source. For example, the power source may be a DC / DC power source for one or more light sources (e.g., LEDs). Alternatively, the power source may be a DC / DC power source for a USB output associated with the device (400). In some embodiments, the load (410) may be a passive electrical component (e.g., a resistor).

[0027] The battery pack (300) may include a battery controller (320). The battery controller (320) may be configured to estimate the charge state of one or more battery cells (310). For example, the battery controller (320) may include one or more memory devices (322) configured to store a charge state algorithm that can be executed by a processing circuit (324) of the battery controller (320) to allow the battery controller (320) to estimate the charge state of one or more battery cells (310). In some embodiments, the processing circuit (324) may include one or more processors. In alternative embodiments, the processing circuit (324) may include a field programmable gate array (FPGA) or other discrete logic circuits. As discussed in more detail below, the battery controller (320) may be configured to obtain information from the device (400) that enables the battery controller (320) to estimate the charge state of one or more battery cells (310).

[0028] When the battery pack (300) is electrically connected to the device (400), the device (400) may provide data to the battery controller (320). The data may represent the power consumption for the device (400). For example, the controller (420) associated with the device (400) may be configured to provide data to the battery controller (320) via a communication link (440). In some embodiments, the communication link (440) may include a wired communication link (e.g., one or more pins or terminals). In alternative embodiments, the communication link (440) may include a wireless communication link. It should be understood that the data representing the power consumption associated with the device (400) may be provided as input to a charge state algorithm executed by the processing circuit (324) of the battery controller (320).

[0029] In some embodiments, data indicating the power required for the device (400) may include data indicating one or more electrical parameters associated with the device (400). For example, one or more electrical parameters may include the maximum current that the device (400) must draw to perform a task. In some embodiments, one or more electrical parameters may include the rated current for the device (400). In some embodiments, one or more electrical parameters may include the maximum power that the device (400) must draw to perform a task. In some embodiments, one or more electrical parameters may include the impedance of the device (400) (e.g., normal, minimum). However, it should be understood that one or more electrical parameters may include any appropriate parameter of the device that can be used to determine the power required for the device (400).

[0030] In some embodiments, data representing the power consumption associated with the device (400) may include data representing the transient current initially drawn by the device (400) when performing a task. For example, the device (400) may be the cordless power tool (100) described above with reference to FIG. 1, and the task may include drilling a hole or driving a fastener (e.g., a screw). In such embodiments, the data may represent the transient current (e.g., about 40 A) initially drawn by the cordless power tool (100) when performing a task.

[0031] In some embodiments, data representing the power required for the device (400) may include a current profile for the device (400). For example, the current profile may include data representing the current drawn by the device (400) over time. In alternative embodiments, data representing the power required for the device (400) may include a power profile for the device (400). For example, the power profile may include data representing the power drawn by the device (400) over time.

[0032] In some embodiments, data indicating power consumption may include data indicating a model number associated with the device (400). For example, the device (400) may be the cordless power tool (100) described above with reference to FIG. 1, and the data indicating power consumption may include data indicating a model number associated with the cordless power tool (100). In such embodiments, the battery controller (320) may be configured to store a lookup table containing power consumption and model numbers for a plurality of different power tools (e.g., a leaf blower, a chainsaw, an impact driver, etc.). For example, one or more memory devices of the battery controller (320) may be configured to store the lookup table. The battery controller (320) may be configured to match a model number associated with the device (400) to one of the model numbers included in the lookup table. In this way, the battery controller (320) can determine the power required for the cordless power tool (100) based at least partially on data representing a model number associated with the cordless power tool (100).

[0033] The battery controller (320) may be configured to determine the charge state of one or more battery cells (310) based at least partially on data indicating the power required for the device (400). For example, the battery controller (320) may be configured to adjust the charge state of one or more battery cells (310) from a first charge state to a second charge state based at least partially on data indicating the power required for the device (400). In this way, the charge state of one or more battery cells (310) may be adjusted at least partially based on the power required by the device (400) electrically connected to the battery pack (300).

[0034] The battery controller (320) may be configured to provide a notification indicating a determined charge state of one or more battery cells (310) to be displayed on a display device. For example, in some embodiments, the battery controller (320) may be configured to provide a notification to the device (400) via a communication link (440) to be displayed on a display device (430) associated with the device (400). Alternatively or additionally, the battery controller (320) may be configured to provide a notification to be displayed on a display device (330) associated with the battery pack (300).

[0035] Now, referring to FIG. 4, a flowchart of an exemplary method (500) for estimating the charge state of a battery pack according to an exemplary embodiment of the present disclosure is provided. It should be understood that the method (500) may be implemented by the battery controller (320) described above with reference to FIG. 3. Additionally, while FIG. 4 illustrates steps performed in a specific order for the sake of example and discussion, the methods of the present disclosure are not limited to the specifically illustrated order or arrangement. It should be understood that various steps of the method (500) may be omitted, rearranged, combined, and / or adjusted in various ways without departing from the scope of the present disclosure.

[0036] In step (502), the method (500) includes the step of obtaining data from a device electrically connected to the battery pack by the battery controller of the battery pack. The data may represent the power consumption of the device. Additionally, the device may be configured to provide data representing the power consumption to the battery controller via a wired or wireless communication link.

[0037] In some embodiments, data representing the power required for the device may include data representing one or more electrical parameters associated with the device. For example, one or more electrical parameters may include the maximum current that the device must draw to perform a task. In some embodiments, one or more electrical parameters may include the rated current for the device. In some embodiments, one or more electrical parameters may include the maximum power that the device must draw to perform a task. In some embodiments, one or more electrical parameters may include the impedance of the device (e.g., normal, minimum). However, it should be understood that one or more electrical parameters may include any suitable parameter that can be used to determine the power required for the device.

[0038] In some embodiments, data indicating the power required for the device may include data indicating the transient current that the device initially draws when performing a task. For example, the device may be a cordless power drill, and the task may include drilling a hole or driving a fastener (e.g., a screw). In such embodiments, the data may indicate the transient current (e.g., about 40 Amps) that the cordless power drill initially draws when performing a task.

[0039] In some embodiments, data representing the power required for the device may include a current profile for the device. For example, the current profile may include data representing the current drawn by the device over time. In alternative embodiments, data representing the power required for the device may include a power profile for the device. For example, the power profile may include data representing the power drawn by the device over time.

[0040] In some embodiments, data indicating power consumption may include data indicating a model number associated with the device. For example, the device may be a cordless power tool, and the data indicating power consumption may include data indicating a model number associated with the cordless power tool. In such embodiments, the battery controller may be configured to store a lookup table containing power consumption and model numbers for a plurality of different power tools (e.g., a leaf blower, a chainsaw, an impact driver, etc.). For example, one or more memory devices of the battery controller may be configured to store the lookup table. The battery controller may be configured to match a model number associated with the device with one of the model numbers included in the lookup table. In this way, the battery controller may determine the power consumption for the device based at least partially on the data indicating the model number associated with the device.

[0041] In step (504), the method (500) includes the step of determining the charge state of a battery pack based at least partially on data indicating power consumption by a battery controller. For example, in some embodiments, the step of determining the charge state of a battery pack may include the step of adjusting the charge state of the battery pack from a first charge state to a second charge state. The second charge state may be lower than the first charge state when a second device electrically connected to the battery pack has a higher power consumption than a first device electrically connected to the battery pack immediately before the second device.

[0042] In step (506), the method (500) includes the step of providing a notification by the battery controller indicating the charge status determined in step (504) for displaying on a display device. For example, in some embodiments, the display device may be associated with a device. Alternatively or additionally, the display device may be associated with a battery pack. In this way, a user associated with the device and / or battery pack may see a notification indicating the charge status.

[0043] Now, referring to FIG. 5, graphs illustrating how the available capacity of a battery pack or battery-driven system differs for devices having different power requirements are illustrated according to an exemplary embodiment of the present disclosure. As illustrated, graph (600) illustrates curves (610, 620, 630) corresponding to voltage (indicated as volts (V) along the vertical axis) as a function of the capacity of the battery pack (indicated as ampere-hours along the horizontal axis). Curve (610) corresponds to the open-circuit voltage of the battery pack, that is, the voltage of the pack or cell at any SOC when a device having low power requirements is applied to the cell(s) or when such a device is absent. Curve (620) corresponds to the external battery voltage of the battery pack when the battery pack is electrically connected to a first device having a first power requirement. Curve (630) corresponds to the external battery voltage of the battery pack when the battery pack is electrically connected to a second device having a second power requirement different from the first power requirement. For example, the second power required associated with the second device may differ from the first power required associated with the first device (e.g., it may be higher). More specifically, the initial current drawn by the second device may be higher than the initial current drawn by the first device. In this way, the voltage drop across the battery pack when connected to the second device is greater than the voltage drop across the battery pack when connected to the first device.

[0044] As illustrated, the curve (630) intersects the line (640) corresponding to the shutdown voltage of the battery pack or battery-powered system before the curve (620) intersects the line (640). It should be understood that the points where the curves (610, 620, 630) intersect the line (640) correspond to the available capacity (Quse) of the battery pack when connected to a device with low power consumption, a first device with first power consumption, and a second device with second power consumption, respectively. For example, the battery pack has a maximum capacity (650) when connected to a device with low power consumption. Subsequently, the battery pack has a smaller available capacity (660) when connected to the first device, and a much smaller available capacity (670) when connected to the second device. This is, in part, because the first power requirement of the first device is greater than the lower power requirement, and the second power requirement of the second device (e.g., initial current) is greater than the first power requirement of the first device (e.g., initial current).

[0045] The amount of charge (e.g., Qpass) that has already been depleted (i.e., transferred from the battery pack to the device) is indicated by line (680) on graph (600). It should be understood that as the battery pack or battery-powered system continues to transfer charge to the device, line (680) moves to the right (e.g., closer to the available capacity). Additionally, it should be understood that the state of charge (SOC) of the battery pack can be determined using the formula below.

[0046]

[0047] In this formula, Qpass corresponds to the amount of charge already depleted. Additionally, Quse corresponds to the available capacity of the battery pack. As illustrated in graph (600), the difference (690) (e.g., delta) between line (680) and the available capacity (660) of the first device is greater than the difference (692) (e.g., delta) between line (680) and the available capacity (670) of the second device. Thus, the SOC of the battery pack or battery-powered system when connected to the first device is greater than the SOC of the battery pack or battery-powered system when connected to the second device. This is partly because the first power required (e.g., initial current) associated with the first device is lower than the second power required (e.g., initial current) associated with the second device.

[0048] As described above, the battery controller of the battery pack according to the present disclosure may be configured to adjust the charge state of the battery pack to account for variations in the power requirements of different devices that may be connected to the battery pack. In this way, the charge state of the battery pack determined by the battery controller according to the present disclosure may be specified for the device currently connected to the battery pack.

[0049] Now, referring to FIG. 6, a flowchart of a method (700) for controlling the operation of a device electrically connected to a battery pack according to an exemplary embodiment of the present disclosure is provided. It should be understood that the method (700) may be implemented by the controller (420) of the device (400) described above with reference to FIG. 3. Additionally, while FIG. 6 illustrates steps performed in a specific order for the sake of example and discussion, the methods of the present disclosure are not limited to the specifically illustrated order or arrangement. It should be understood that various steps of the method (700) may be omitted, rearranged, combined, and / or adjusted in various ways without departing from the scope of the present disclosure.

[0050] In step (702), the method (700) may include the step of obtaining data from a battery pack electrically connected to the device by a controller of the device. The data may represent the impedance of the battery pack. In some embodiments, the battery controller of the battery pack may provide data (e.g., impedance) to the device via a wired communication link. In alternative embodiments, the battery controller may provide data to the device via a wireless communication link.

[0051] In step (704), the method (700) may include a step of determining, by the device controller, a control of the maximum amount of power drawn from the battery pack based at least partially on the data obtained in step (702). For example, the step of determining the control of the maximum amount of power drawn from the battery pack by the device's electric motor may include a step of controlling the current drawn by the electric motor from the battery pack by the battery controller. More specifically, the current drawn by the electric motor from the battery pack may be reduced when the data obtained in step (702) indicates that the impedance of the battery pack is below a threshold value. In step (706), the method (700) may include a step of controlling the operation of the device so that the device draws the controlled amount of power by the device controller.

[0052] Although the subject matter of the present invention has been described in detail with respect to specific exemplary embodiments thereof, those skilled in the art will understand that changes, variations, and equivalents to these embodiments can be easily made by understanding the foregoing. Accordingly, the scope of the present disclosure is illustrative and not limiting, and the present disclosure does not exclude such modifications, variations, and / or additional inclusions to the subject matter, as would be apparent to those skilled in the art.

Claims

Claim 1 A method for estimating the charge state of a battery pack (200, 300) comprising a plurality of cells (310), comprising the step of obtaining data indicating a power requirement for a power tool (100) from a power tool (100) electrically connected to the battery pack (200, 300) by a battery controller (320) of the battery pack (200, 300); A method comprising the step of determining the charge state of the battery pack (200, 300) based at least partially on data indicating the power required for the power tool (100) by the battery controller (320), wherein the step of determining the charge state of the battery pack (200, 300) based at least partially on data indicating the power required for the power tool (100) includes the step of adjusting the charge state of the battery pack (200, 300) from a first charge state to a second charge state based at least partially on data indicating the power required for the power tool (100) by the battery controller (320), and wherein the step of acquiring data indicating the power required for the power tool (100) includes the step of acquiring data indicating a model number assigned to the power tool (100) by the battery controller (320). Claim 2 In claim 1, the method wherein the second charge state is smaller than the first charge state. Claim 3 A method according to claim 1 or 2, wherein data indicating the power required for the power tool (100) includes data indicating one or more electrical parameters of the power tool (100). Claim 4 In paragraph 3, the data representing one or more electrical parameters includes a maximum current for the power tool (100), a maximum power for the power tool (100), an impedance of the power tool (100), or a rated current for the power tool (100). Claim 5 A method according to claim 1, wherein the step of acquiring data indicating the required power for the power tool (100) includes the step of acquiring data indicating the amount of power required for the electric motor of the power tool (100) to perform work by the battery controller (320). Claim 6 In paragraph 5, the power tool (100) includes a cordless drill, and the operation includes drilling a hole or driving a fastener. Claim 7 A method according to claim 5 or 6, wherein the step of acquiring data indicating the power required for the power tool (100) includes the step of acquiring data indicating the required current that the electric motor of the power tool (100) must draw to perform work by the battery controller (320). Claim 8 In claim 1, the step of determining the charge state of the battery pack (200, 300) includes the step of matching a model number assigned to the power tool (100) to one of a plurality of model numbers included in a lookup table stored in one or more memory devices of the battery pack (200, 300), wherein the lookup table includes the power required for each of the plurality of model numbers. Claim 9 A method comprising, in addition to the step of providing a notification indicating a charge status to be displayed on a display device by the battery controller (320) in accordance with claim 1 or 2 or 5 or 6. Claim 10 In claim 9, the display device is associated with the battery pack (200, 300), in a method. Claim 11 A battery pack (200, 300) comprising one or more battery cells; and a battery controller (320) configured to perform operations, wherein the operations include obtaining data indicating the power required for the power tool (100) from a power tool (100) electrically connected to the one or more battery cells; A battery pack comprising determining the charge state of the battery pack (200, 300) based at least partially on data indicating the power required for the power tool (100), wherein determining the charge state of the battery pack (200, 300) based at least partially on data indicating the power required for the power tool (100) includes adjusting the charge state of the battery pack (200, 300) from a first charge state to a second charge state by the battery controller (320) based at least partially on data indicating the power required for the power tool (100), and acquiring data indicating the power required for the power tool (100) includes acquiring data indicating a model number assigned to the power tool (100) by the battery controller (320). Claim 12 delete Claim 13 delete Claim 14 delete Claim 15 delete Claim 16 delete Claim 17 delete Claim 18 delete Claim 19 delete Claim 20 delete Claim 21 delete Claim 22 delete Claim 23 delete Claim 24 delete

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