Battery pack with temperature-limited current

Abstract

The battery pack may include one or more cells. The battery pack may include at least one temperature sensor configured to obtain a temperature measurement indicative of the temperature of at least one of the one or more cells. The battery pack may include a controller configured to control signal communication with a battery charger. The controller may be configured to perform operations. The operations may include obtaining the temperature measurement from the at least one temperature sensor. The operations may include determining that the temperature of the at least one cell is between a lower temperature threshold and an upper temperature threshold at least in part based on the temperature measurement. The operations may include reducing a maximum charging current in response to determining that the temperature of the at least one cell is between the lower temperature threshold and the upper temperature threshold, wherein reducing the maximum charging current includes reducing the maximum charging current at least in part based on an inverse functional relationship between the temperature measurement and the maximum charging current. The operations may include controlling the battery charger at least in part based on the maximum charging current to charge the one or more cells.

Description

Technical Field

[0001] Example aspects of the present disclosure relate to an electrical energy storage device, such as a battery pack including a plurality of battery cells, and a system and method for charging the same. Background Art

[0002] Battery packs are commonly used in portable electrical devices and tools, enabling these devices and tools to be used in environments without a fixed power source. For example, power tool manufacturers typically produce universal power packs that can be compatibly used with different types of cordless power tools, such as electric drills, hammers, screwdrivers, impact wrenches, angle grinders, etc. A battery pack generally includes a plurality of battery cells housed in an integral housing, and a user can easily install or remove the entire battery into or from a power tool via a latch mechanism configured on the battery pack housing and / or the power tool. Summary of the Invention

[0003] Aspects and advantages of embodiments of the present disclosure will be set forth in part in the following description, or may be learned from the description, or may be learned by practice of the embodiments.

[0004] An example aspect of the present disclosure relates to a battery pack. The battery pack may include one or more cells. The battery pack may include at least one temperature sensor configured to obtain a temperature measurement indicative of the temperature of at least one of the one or more cells. The battery pack may include a controller configured to control signal communication with a battery charger. The controller may be configured to perform operations. The operations may include obtaining the temperature measurement from the at least one temperature sensor. The operations may include determining that the temperature of the at least one cell is between a lower temperature threshold and an upper temperature threshold at least in part based on the temperature measurement. The operations may include reducing a maximum charging current in response to determining that the temperature of the at least one cell is between the lower temperature threshold and the upper temperature threshold, wherein reducing the maximum charging current includes reducing the maximum charging current at least in part based on an inverse function relationship between the temperature measurement and the maximum charging current. The operations may include controlling the battery charger at least in part based on the maximum charging current to charge the one or more cells.

[0005] Another example aspect of the present disclosure relates to a method for charging a battery pack while avoiding overheating conditions. The method can include obtaining a temperature measurement indicating the temperature of at least one cell from the at least one temperature sensor. The method can include determining that the temperature of the at least one cell is between a lower temperature threshold and an upper temperature threshold, at least in part based on the temperature measurement. The method can include reducing a maximum charging current in response to determining that the temperature of the at least one cell is between the lower temperature threshold and the upper temperature threshold, wherein reducing the maximum charging current includes reducing the maximum charging current at least in part based on an inverse functional relationship between the temperature measurement and the maximum charging current. The method can include controlling the battery charger, at least in part based on the maximum charging current, to charge the at least one cell.

[0006] Other aspects of the present disclosure relate to various systems, devices, non-transitory computer-readable media, user interfaces, and electronic devices.

[0007] These and other features, aspects, and advantages of the various embodiments of the present disclosure will be better understood with reference to the following description and the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate example embodiments of the present disclosure and, together with the description, serve to explain the relevant principles. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 An example tool battery in accordance with an example embodiment of the present disclosure is shown.

[0009] Figure 2 An example cordless (battery-powered) tool in accordance with an example embodiment of the present disclosure is shown.

[0010] Figure 3 A schematic diagram of an example battery pack charging system in accordance with an example embodiment of the present disclosure is shown.

[0011] Figure 4 An example temperature-current curve in accordance with an example embodiment of the present disclosure is shown.

[0012] Figure 5 A graph of battery parameters during a charging process in accordance with an example embodiment of the present disclosure is shown.

[0013] Figure 6 A flowchart of an example method for charging a battery pack to avoid overheating conditions in accordance with an example embodiment of the present disclosure is shown.

[0014] Figure 7 A flowchart of an example method for charging a battery pack to mitigate overheating conditions in accordance with an example embodiment of the present disclosure is shown.

[0015] In the drawings, in all several embodiments described herein, like numerals indicate like parts. Detailed Description

[0016] In the foregoing description of the claims and the exemplary aspects of the present disclosure, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e., to specify the presence of the recited features, but not to preclude the presence or addition of further features in the various embodiments of the exemplary aspects of the present disclosure.

[0017] As used herein and in the claims, unless otherwise specified, "coupled" or "connected" means directly or indirectly electrically coupled or electrically connected via one or more electrical devices.

[0018] As used herein, terms such as "horizontal", "vertical", "upward", "downward", "above", "below" and similar terms are for the purpose of describing the normal use orientation of the exemplary embodiments and are not intended to limit the present disclosure to any particular orientation.

[0019] Exemplary aspects of the present disclosure relate to battery packs. A battery pack may include one or more cells. The one or more cells may store and / or transfer charge (e.g., as energy) to an electrical power device such as a power tool, a gardening tool, etc. The battery pack may be configured to have various DC voltage levels (e.g., 12 volts, 18 volts, 24 volts, 28 volts, 40 volts, etc.). For example, the battery pack may be a 12-volt battery pack, a 28-volt battery pack, a 40-volt battery pack or another voltage. In an example, the battery pack may include one or more lithium-ion (Li-ion) cells, and the one or more lithium-ion cells are arranged to output direct current at the rated voltage of the battery pack. In some embodiments, the electrodes of the cell may be or may include graphite electrodes. Other suitable materials may be included in the electrodes of the cell.

[0020] In some embodiments, the battery cells in the battery pack may be rechargeable lithium-ion battery cells. In other configurations, the battery cells may have a chemistry other than lithium-ion, e.g., nickel cadmium (NiCa or NiCad), nickel metal hydride, etc. In one embodiment, the battery is a power tool battery pack including a battery pack housing that contains one or more battery cells and a latch mechanism for selectively securing the battery pack to a battery interface.

[0021] In addition, a battery pack including one or more cells can be charged and / or recharged by a battery charger. For example, the battery pack can be connected to a battery charger configured to receive the battery pack (such as configured to receive the battery pack into a battery receiving seat). As an example, the battery pack can include one or more slot mechanical connectors (e.g., rails) configured to engage with one or more slots at the battery charger to couple the battery pack to the battery charger. When the battery pack is connected to the battery charger, the battery charger can supply power (e.g., voltage and / or current) to the battery pack (e.g., one or more cells) to charge the battery by increasing the charge of the (multiple) cells. In some embodiments, the battery pack and / or the battery charger can be configured in a constant voltage mode, such as by supplying a constant voltage to the battery pack by reducing the current over time while charging the battery to maintain a constant (e.g., specified) voltage. Additionally and / or alternatively, the battery pack and / or the battery charger can be configured in a constant current mode, which supplies a constant (e.g., specified) current to the battery pack. This generally causes the voltage of the battery pack (e.g., cell voltage) to increase with charge.

[0022] The battery pack can include a battery controller. The battery controller can control signal communication with the battery charger, such as signal communication with a charger controller of the battery charger. For example, when the battery pack is received by the battery charger, the battery controller can be coupled (e.g., coupled through one or more signal pins and / or other terminals) to the charger controller. The battery controller can request a certain amount of current from the battery charger to charge the battery. For example, the battery controller can transmit data indicating the amount of current that the requested battery charger will supply to the charger controller. The charger controller can control the battery charger to supply the requested amount of current to the battery. In some embodiments, the requested amount of current can be a current limit. For example, the charger can deliver an amount of current less than or equal to the current limit. For example, if the battery pack transmits a request for 6 amperes to a battery charger that can only supply 4 amperes, the battery charger can only supply 4 amperes. However, if the battery pack transmits a request for 2 amperes to the same 4 - ampere battery charger, the battery charger can supply 2 amperes. In this way, the battery pack can intelligently limit the amount of current it receives while being compatible with various chargers.

[0023] Typically, a battery pack may be affected by temperature limitations. For example, the battery pack may have to be maintained at or below a temperature upper limit. During use and / or charging, the battery temperature may rise. Exceeding the temperature upper limit and thus causing an over-temperature situation may lead to safety risks, shortened battery life, damage to the battery and / or other systems, and / or other problems, etc. Additionally, in an over-temperature situation, it may be necessary to mitigate the over-temperature situation, such as by aborting charging until the battery pack returns to a lower temperature. This may significantly increase the amount of time required to charge the battery pack. Therefore, it is generally desirable to avoid over-temperature situations by maintaining the battery pack at or below the temperature upper limit and / or by avoiding exceeding the temperature upper limit.

[0024] According to an example aspect of the present disclosure, a battery controller may monitor the temperature of a battery pack. As an example, the battery controller may monitor the temperature of the cell(s) of the battery pack. For example, in some embodiments, the battery pack may include one or more temperature sensors corresponding to at least one cell. The temperature sensor(s) may obtain temperature measurements from at least one cell. The battery controller may obtain the temperature measurements from the temperature sensor(s).

[0025] In some embodiments, a battery charger may obtain the temperature measurement. For example, in some embodiments, the temperature measurement may be obtained at a temperature measurement terminal of the battery pack. For example, when the battery pack is received at a device (e.g., a battery charger), the temperature measurement terminal may transmit a temperature measurement signal (e.g., a digital and / or analog signal) describing the temperature measurement to the device (e.g., a battery charger) to which the battery pack is coupled.

[0026] According to an example aspect of the present disclosure, the battery controller may be configured to perform operations. These operations may include, for example, a method of charging the battery pack while avoiding over-temperature situations. For example, according to an example aspect of the present disclosure, the battery controller may implement these operations to charge the battery while preventing over-temperature situations. Additionally, if an over-temperature situation occurs unavoidably, in some embodiments, these operations may help mitigate the over-temperature situation.

[0027] The method may include obtaining a temperature measurement indicating the temperature of at least one cell from a temperature sensor. The temperature measurement may indicate the temperature of the battery pack (e.g., the temperature of at least one cell). The temperature measurement may be transmitted to the battery controller. In an example embodiment, a single temperature sensor is configured to obtain a temperature measurement of one cell to determine the temperature of the battery pack. For example, the temperature measurement of a single cell may be extrapolated to represent the temperature of the battery pack. According to an example embodiment of the present disclosure, other suitable temperature measurement configurations may be employed.

[0028] The method may include determining that the temperature of the at least one cell is between a lower temperature threshold and an upper temperature threshold, at least in part based on the temperature measurement. For example, the lower temperature threshold may be the temperature at which it is desired to start reducing the battery pack current to avoid overheating. Generally, the lower temperature threshold may be any suitable temperature and may be a temperature lower than (e.g., approximately 10 degrees Celsius lower than) the upper temperature threshold. Additionally, in some embodiments, the upper temperature threshold may be at the upper temperature limit, such as the temperature at which an overheating condition occurs. The battery controller may determine that the temperature of the at least one cell is between the lower temperature threshold and the upper temperature threshold in any suitable manner (e.g., by threshold comparison). Additionally and / or alternatively, the determination may be performed by inputting the temperature into a mathematical model.

[0029] Additionally and / or alternatively, the method may include reducing the maximum charging current in response to determining that the temperature of the at least one cell is between the lower temperature threshold and the upper temperature threshold. For example, reducing the maximum charging current may include reducing (e.g., via a charging current request) the maximum charging current requested from a battery charger. According to an example aspect of the present disclosure, reducing the maximum charging current may include reducing the maximum charging current at least in part based on an inverse functional relationship between the temperature measurement and the maximum charging current. For example, the inverse functional relationship may give that as the temperature of the at least one cell rises over at least a portion of the region between the lower temperature threshold and the upper temperature threshold, the maximum charging current will decrease. For example, the inverse functional relationship may give that the maximum charging current at the upper temperature threshold is at least less than the maximum charging current at the lower temperature threshold. Additionally and / or alternatively, the maximum charging current may be allowed to recover (e.g., increase) as the temperature decreases (e.g., after reducing the current). In some embodiments, the inverse functional relationship may be a monotonically decreasing relationship. For example, in some embodiments, the inverse functional relationship may be a linearly decreasing relationship. For example, the maximum charging current may decrease linearly with an increase in temperature. According to an example aspect of the present disclosure, other suitable functional relationships such as an exponential decay function, a step function, etc. may be employed.

[0030] In some embodiments, the inverse function relationship can be or can include a mathematical model or function. For example, a computing system can calculate a maximum charging current based on a formula or a mathematical model. As another example, the inverse function relationship can be or can include a look-up table. For example, the maximum charging current can be retrieved from a look-up table in which temperature is provided as an input. According to an example aspect of the present disclosure, other systems suitable for leveraging an inverse function relationship (e.g., determining a threshold) can be employed. As an example, the maximum charging current can be determined with respect to a temperature-based current limit in a temperature-current curve. The temperature-current curve can be stored in a non-transitory computer-readable medium, such as flash memory, RAM, ROM, EEPROM, hard disk memory, solid state memory, and / or any other suitable memory. For example, in some embodiments, the curve can be stored as a look-up table, a mathematical relationship or model, or other suitable representation.

[0031] In some embodiments, the maximum charging current can be based on various other current limits established with respect to other factors of the battery pack. For example, the (multiple) current limits can be determined according to various criteria of the battery, such as but not limited to state of charge, battery voltage, cell voltage, charging type (e.g., constant current or constant voltage), charging state, charging progress, etc. One of these current limits can be determined with respect to the temperature of the battery pack, such as based on an inverse function relationship between temperature and charging current. For example, the lowest current limit can be used as the maximum charging current.

[0032] Additionally and / or alternatively, the method can include requesting from a battery charger a maximum charging current for charging one or more cells. For example, in some embodiments, a battery controller can determine a charging current request. The charging current request can specify the amount of current requested to be provided to the battery to charge the battery, such as the maximum charging current. The charging current request can be transmitted to a battery charger such as a charger controller. In some embodiments, the maximum charging current can be requested from the battery charger periodically. For example, the maximum charging current can be requested at periodic intervals, such as at set time intervals (including regular intervals and / or irregular intervals), in response to a stimulus, etc. For example, the maximum charging current can be determined and requested at regular intervals to ensure that the current is updated when necessary.

[0033] After receiving a charging current request, a charger controller may configure a battery charger (e.g., a power source) to deliver the amount of current specified by the charging current request to a battery pack (e.g., a plurality of cells). As an example, the battery pack and / or the battery charger may include one or more charging terminals configured to provide an electrical connection between one or more cells and the battery charger (such as between one or more cells and a power source). In some embodiments, the charging current request is transmitted to the battery charger periodically. For example, the charging current request may be transmitted at set time intervals or in response to a stimulus, etc.

[0034] In some embodiments, the battery controller may further be configured to mitigate an over-temperature condition of the battery pack. For example, example aspects of the present disclosure may generally reduce the likelihood of an over-temperature condition, such as by reducing the current to the battery pack to thereby reduce the temperature of the battery pack. Nevertheless, in some example cases, if an over-temperature condition has been reached, it may still be desirable to completely abort charging the battery pack.

[0035] For example, the method may further include determining that the temperature of at least one cell is above an upper temperature threshold based at least in part on a temperature measurement. For example, the battery controller may compare the temperature of the (plurality of) cells to the upper temperature threshold. If the temperature reaches or exceeds the upper temperature threshold, it may be desirable to abort charging the battery pack. For example, in response to determining that the temperature of one or more cells is above the upper temperature threshold, the method may include aborting charging the battery pack. For example, aborting charging the battery pack may include requesting a minimum current from the battery charger while charging is aborted. The minimum current may be a current equal to or close to zero amperes, such as a current less than about 0.1 amperes such as 0 amperes. For example, aborting charging the battery pack may include transmitting an abort current request to the battery charger, where the abort current request includes a request for about zero amperes.

[0036] The battery controller may further be configured to determine that the temperature of at least one cell is below a lower temperature threshold after aborting charging the battery. For example, the temperature of the at least one cell being below the lower temperature threshold may generally indicate that charging may be safely resumed. In response to determining that the temperature of one or more cells is below the lower temperature threshold, the method may include resuming charging the battery pack. For example, as described herein, once the battery pack reaches the lower temperature threshold, the battery controller may re-determine the maximum charging current based on the temperature measurement.

[0037] For illustrative purposes, some example aspects of the present disclosure may be discussed herein with reference to a battery controller that performs the following operations, for example: obtaining a temperature measurement from at least one temperature sensor; determining that the temperature of at least one cell is between a lower temperature threshold and an upper temperature threshold based at least in part on the temperature measurement; in response to determining that the temperature of the at least one battery is between the lower temperature threshold and the upper temperature threshold, reducing a maximum charging current, wherein reducing the maximum charging current includes reducing the maximum charging current based at least in part on an inverse functional relationship between the temperature measurement and the maximum charging current; and requesting from a battery charger a maximum charging current for charging one or more cells. It should be understood that some or all of these steps may be performed on a computing device other than a battery controller (e.g., a charger controller). For example, in some embodiments, a battery pack may transmit the temperature measurement to the battery charger, such as via communication terminals or communication pins on the battery pack and / or the battery charger. The charger controller may obtain the temperature measurement from the battery pack (e.g., via the terminals) and perform operations to limit the maximum charging current at the controller. This may be beneficial in cases where the battery pack cannot perform the methods described herein (such as when the battery pack lacks a battery controller, when providing legacy support for a battery with non-updatable firmware, etc.).

[0038] Example aspects of the present disclosure may provide a variety of technical effects and benefits. As an example, example aspects of the present disclosure may shorten the charging time of a battery pack. For example, in the case where the battery pack exceeds the upper temperature limit, charging may have to be aborted. The systems and methods according to example aspects of the present disclosure may enable proactively reducing the current from the charger before the battery pack reaches the upper temperature limit (such as the upper temperature limit). In this way, the battery pack can avoid reaching the upper temperature limit, which in turn can prevent extremely time-consuming charging interruptions due to reaching the upper temperature limit. As another example, example aspects of the present disclosure may increase battery life. For example, example aspects of the present disclosure may keep the battery at or below the upper temperature limit, which can prevent a shortening of battery life associated with exceeding the upper temperature limit.

[0039] Referring now to the drawings, for illustrative purposes, example embodiments of the present disclosure will be discussed with reference to the drawings. Figure 1 and Figure 2Shows a typical tool battery 10 and a cordless (battery-powered) tool 20. The tool 20 shown is a drill or driver having a tool housing 21 and a pistol grip 24. A motor 23 (indicated by the dashed line) is located within the housing to drive a tool output 22. The battery 10 can be connected to be supported by the tool handle 24. A tool controller such as a trigger 25 is located near the junction between the housing 21 and the handle 24 to couple energy from the battery 10 to the motor 23. However, this is not intended to limit the scope of use of the battery according to the exemplary aspects of the present disclosure. Such a battery can be used for other types of cordless tools, and especially for handheld cordless tools, or cordless lawn and garden equipment such as lawn mowers, hedge trimmers, etc. Such a battery can also be used for floor care products such as vacuum cleaners, handheld vacuum cleaners, and cordless sweepers.

[0040] One embodiment of a battery for these types of cordless tools has a battery pack housing 11 that has a mating surface 12 for connection to the tool. The battery pack housing 11 can be selectively received and supported by the tool housing via battery connection features and can be selectively separated from the tool for charging in a separate charger (not shown). For example, Figure 1 An example embodiment of the battery mating features is shown. In the embodiment shown, the battery connection features are terminal posts 13 and battery terminals 14, 15 on the terminal posts 13 for connecting the battery energy source and the tool controller or trigger 25. In an alternative embodiment, the battery connection features can be a slide-type or rail-type connection feature, or any other type of battery connection feature known in the art. For example, instead of being included on the terminal posts 13, the battery terminals 14 and 15 can be arranged on the mating surface 12 and configured to engage when the battery 10 is received at the tool handle 24 by sliding the battery 10 along one or more rails. Any other suitable battery connection features can be employed according to the exemplary embodiments of the present disclosure.

[0041] Figure 3Shows a schematic diagram of an example battery pack charging system 300 in accordance with an example embodiment of the present disclosure. The battery pack charging system 300 may include a battery charger 310. The battery charger 310 may be removably coupled to the battery pack 320. For example, the battery charger 310 may be configured to receive the battery pack 320. As an example, the battery charger 310 may receive the battery pack 320 at a cavity, a slot, and / or other attachment mechanism that is configured to couple to the battery charger 310 and the battery pack 320 and / or establish electrical communication (e.g., signal communication) between the battery charger 310 and the battery pack 320. As an example, the battery pack 320 may include one or more slot mechanical connectors that are configured to engage one or more slots at the battery charger 310 to couple the battery pack 320 to the battery charger 310.

[0042] The battery pack 320 may include one or more cells 322. The one or more cells 322 may store and / or transfer charge (e.g., as a power source) to an electric power device such as a power tool, a gardening tool, etc. Additionally, the one or more cells 322 may be charged and / or recharged via the battery charger 310. For example, the battery pack 320 may be connected to a battery charger 310 that is configured to receive the battery pack 320 (such as being configured to receive the battery pack 320 into a battery receiving seat). When the battery pack 320 is connected to the battery charger 310, the battery charger 310 may supply power (e.g., voltage and / or current) to the battery pack 320 (e.g., to the one or more cells 322) via a power signal (such as a voltage signal and / or a current signal) to charge the battery by increasing the charge of the (one or more) cells. In some embodiments, the battery pack 320 and / or the battery charger 310 may be configured in a constant voltage mode, such as by decreasing the current over time to maintain a constant voltage at the battery charger 310 to provide a constant voltage signal to the battery pack. Additionally and / or alternatively, the battery pack 320 and / or the battery charger 310 may be configured in a constant current mode, which provides a constant current signal to the battery pack 320. This typically causes the voltage of the battery pack 320 (e.g., the cell voltage) to rise with the state of charge.

[0043] The battery charger 310 can be configured to charge the battery pack 320. For example, the battery charger 310 can include a power source 312. The power source 312 can be configured to provide power for charging the battery pack 320 by supplying a power signal (such as a voltage signal and / or a current signal) to the (multiple) cells 322 of the battery pack 320. For example, the power source 312 can supply the power stored in the cells 322. The power source 312 can be a DC power source configured to provide a DC power signal, such as a DC power source including an AC / DC converter. For example, the power source 312 can receive a first power signal (such as an AC signal such as an AC signal from a power outlet, etc.) and convert the first power signal into a second power signal (such as a DC signal such as a DC current signal rated for charging the battery pack 320).

[0044] The battery pack 320 can include a battery controller 324. The battery controller 324 can control signal communication with the battery charger 310, such as signal communication with the charger controller 314 of the battery charger 310. For example, when the battery charger 310 accepts the battery pack 320, the battery controller 324 can be coupled (e.g., through one or more signal pins and / or other terminals) to the charger controller 314. The battery controller 324 can request a certain amount of current from the battery charger 310 to charge the battery. For example, the battery controller 324 can send the request to the charger controller 314 to request the battery charger 310 to provide the requested amount of current. The charger controller 314 can control the battery charger 310 to provide the requested amount of current to the battery. For example, the battery charger 310 and / or the battery pack 320 can include one or more charging terminals configured to provide an electrical connection and / or electrical communication between one or more cells 322 and the battery charger 310 (e.g., the power source 312). The charging terminals can be connectable and / or disconnectable such that the battery pack 320 can be removed from the battery charger 310 and / or connected to a device utilizing the battery pack 320, such as a power tool.

[0045] In some embodiments, the requested amount of current can be a current limit. For example, the charger can deliver an amount of current less than or equal to the current limit. For example, if the battery pack 320 sends a request for 6 amperes to a battery charger 310 that can only supply 4 amperes, the battery charger 310 can only supply 4 amperes. However, if the battery pack 320 sends a request for 2 amperes to the same 4 - ampere battery charger 310, the battery charger 310 can supply 2 amperes.

[0046] Power supply 312 can be controlled by charger controller 314. For example, charger controller 314 can obtain (e.g., from battery controller 324) and / or otherwise determine the amount of voltage and / or current to be provided to battery pack 320. Charger controller 314 can configure power supply 312 to provide the determined amount of voltage and / or current to battery pack 320. For example, in some embodiments, the charger controller can adjust the characteristics of one or more digital signals such as a pulse width modulation (PWM) signal to configure the amount of current and / or voltage and / or power provided by power supply 312. For example, the controller can adjust the voltage and / or current at battery pack 320 by adjusting the duty cycle, frequency / cycle, etc. of one or more pulse width modulation circuits at power supply 312. As another example, in some embodiments, charger controller 314 can adjust other components of power supply 312 (such as variable components such as variable resistors, varactors, switches, etc.) to configure the amount of current and / or voltage and / or power provided by power supply 312. For example, as described herein, charger controller 314 can be configured to adjust the power signal from power supply 312 (e.g., for charging cells 322) at least in part based on a maximum charge current (e.g., the maximum charge current from battery controller 324).

[0047] In some embodiments, control of battery charger 310 can be performed at least in part by another controller other than battery controller 324, such as charger controller 314. For example, in some embodiments, battery pack 320 can directly transmit temperature measurements from temperature sensor 326 to charger controller 314, such as via temperature measurement terminals on battery pack 320 and / or battery charger 310. As described herein, charger controller 314 can obtain (e.g., indirectly) temperature measurements from temperature sensor 326 (e.g., via temperature measurement terminals) and control power supply 312 based on the temperature measurements. This can be beneficial in cases where battery pack 320 cannot perform the methods described herein (such as in cases where battery pack 320 lacks battery controller 324, providing legacy support for battery pack 320 with firmware that cannot be updated (e.g., at battery controller 324), etc.).

[0048] Now referring to Figure 4 , an example temperature-current curve 400 that can be employed in accordance with example aspects of the present disclosure is shown. Figure 4Shows an example temperature - current curve 400 according to an example embodiment of the present disclosure. Curve 400 can generally describe the behavior of some embodiments according to an example embodiment of the present disclosure. For example, using the temperature - current curve 400 can be an example of implementing the systems and methods described herein. As other examples, the systems and methods described herein can be implemented through threshold checks, look - up tables, mathematical functions and / or models, approximations of curve 400 (e.g., discretizing the curve), and / or other suitable representations.

[0049] The temperature - current curve 400 can include a temperature - independent region 410, a temperature - reverse region 420, and an over - temperature region 430. For example, the temperature - reverse region 420 can span from a lower temperature threshold 422 to an upper temperature threshold 424. For example, the temperature - reverse region 420 can span from the lower temperature threshold at the lower temperature threshold 422 to the upper temperature threshold at the upper temperature threshold 424. For example, the temperature - reverse region can span a portion of the temperature - current curve that is bounded by the lower temperature threshold 422 and the upper temperature threshold 424. The temperature - reverse region 420 can define an inverse relationship between temperature and current within the temperature - reverse region 420. For example, the current may decrease throughout the temperature - reverse region 420.

[0050] The temperature - independent region 410 can include some or all of the temperatures below the lower temperature threshold 422. As shown, the current can be constant and / or not vary with temperature within the temperature - independent region 410. For example, within the temperature - independent region 410, the current limit may not be affected by temperature. For example, the temperature - independent region 410 can define a constant value such as an upper limit of the total current on the battery pack 320.

[0051] In addition, the over - temperature region 430 can include some or all of the temperatures above the upper temperature threshold (e.g., temperature upper limit) 424. For example, it may be desirable to maintain the temperature of the battery pack (e.g., battery pack 320) at the upper temperature threshold 424 and / or below the upper temperature threshold 424. Thus, when the temperature is at and / or above the upper temperature threshold 424, the current can be reduced to zero.

[0052] In some embodiments, if the temperature of the battery pack enters the over - temperature region 430 (e.g., exceeds the upper temperature threshold 424), the battery pack can abort the current charge until the battery pack reaches the lower temperature threshold, such as the lower temperature threshold 422. For example, if the temperature enters the over - temperature region 430, the temperature - current curve can move to a cooling region 425 (e.g., instead of the temperature - reverse region 420) so that the temperature of the battery pack cools to reach the lower temperature threshold 422. For example, the battery pack can request a minimum current until the temperature of the battery pack reaches the lower temperature threshold 422, at which point the battery pack can resume following the temperature - reverse region 420.

[0053] Figure 5 FIG. 500 shows battery parameters during a charging process according to an example embodiment of the present disclosure. For example, FIG. 500 includes a current curve 502. The current curve 502 shows the variation of the amount of current (e.g., in amperes) supplied to one or more cells (e.g., from a battery charger) over time. Additionally, FIG. 500 includes a temperature curve 504. The temperature curve 504 shows the variation of the temperature (e.g., in degrees Celsius) of the battery pack being charged (e.g., at least one cell) over time. Additionally, FIG. 500 includes a voltage curve 506. The voltage curve 506 shows the variation of the voltage (e.g., in volts) of the battery pack (e.g., from one or more cells in the battery pack) over time. Additionally, FIG. 500 includes a state-of-charge curve 508. The state-of-charge curve 508 shows the variation of the state of charge (e.g., as a percentage) of the battery pack over time. For example, a state of charge of 100% indicates that the battery is fully charged, while a state of charge of 0% indicates that the battery is depleted.

[0054] FIG. 500 depicts the charging process of the battery at various time stages. For example, at time 512, the battery pack may start charging. For example, as shown by the current curve 502, a non-zero amount of current may be supplied to the battery pack at time 512 to start charging the battery. Prior to time 512, the charge of the battery pack may have been depleted or otherwise used previously, such that the battery pack is in a state of insufficient charge. For example, as shown by the state-of-charge curve 508, the initial state of charge of the battery pack may be close to 0%. Additionally, using the battery pack may heat the battery pack (e.g., one or more cells) to a temperature higher than room temperature or other ambient temperature of the battery pack.

[0055] At time 514, the battery pack may start to reduce the current based on the increase in the temperature of the battery pack. For example, as shown, the "full" amount of current supplied by the charger from time 512 to time 514 may cause the temperature of the battery pack to increase due to the current. At time 514, the temperature of the battery pack may exceed the lower limit of the temperature threshold for the first time, such that the current maximum charging current has an inverse function relationship with the temperature of the battery pack. Additionally and / or alternatively, prior to time 514, the temperature may have exceeded the lower limit of the temperature threshold, but the maximum current reduced due to the temperature may have been greater than the current limit due to another factor and / or the maximum current that the battery charger can provide. As shown by the current curve 502 between time 514 and time 516, the current supplied to the battery pack can vary inversely with the temperature based on the inverse function relationship, such that the battery pack can avoid overheating.

[0056] At time 516, the battery pack can be charged in a constant voltage manner. For example, as described herein, prior to time 516, the battery pack may have been charged in a specified current manner, such as a "constant current" manner, where the current can still vary based on the temperature of the battery pack. However, the voltage of the battery pack is generally expected to rise prior to time 516. However, at 516, charging of the battery pack can be changed to a constant voltage manner to maintain the voltage at which the battery pack is at time 516 (e.g., the rated voltage of the battery pack). As shown by voltage curve 506 and state of charge curve 508 at time 516, the battery is not fully at 100% state of charge. Thus, charging of the battery can continue at a constant voltage until time 518, at which time the battery is fully charged. After time 518, current can still be provided to the battery to maintain a 100% state of charge.

[0057] Figure 6 FIG. 600 is a flow chart showing an example method 600 for charging a battery pack to avoid over-temperature conditions in accordance with an example embodiment of the present disclosure. Although, for purposes of illustration and discussion, Figure 6 the steps are depicted as being performed in a particular order, the methods of the present disclosure are not limited to the specifically illustrated order or arrangement. The various steps of method 600 can be omitted, rearranged, combined, and / or adjusted in various ways without departing from the scope of the present invention.

[0058] Method 600 can be implemented by any suitable computing device that communicates with the battery pack and / or battery charger (such as Figure 3 battery pack 320 and / or battery charger 310). As an example, some of all of the steps of method 600 can be implemented by Figure 3 battery controller 324. As another example, some or all of the steps of method 600 can be implemented by Figure 3 charger controller 314. Method 600 can be executed by any suitable computing structure, such as volatile and / or non-volatile computer readable media, (one or more) processors, programmable logic circuits, and / or programmable logic arrays, application specific integrated circuits, and / or other suitable computing systems.

[0059] Method 600 may include obtaining, at 602, a temperature measurement indicative of the temperature of at least one cell from a temperature sensor. The temperature measurement may indicate the temperature of the battery pack (e.g., the temperature of at least one cell). For example, in some embodiments, the temperature measurement may be communicated from the temperature sensor to a controller such as a battery controller and / or a charger controller. In one example embodiment, a single temperature sensor is configured to obtain a temperature measurement of one cell to determine the temperature of the battery pack. For example, the temperature measurement of a single cell may be extrapolated to represent the temperature of the battery pack. Other suitable temperature measurement configurations may be employed according to example embodiments of the present disclosure.

[0060] Additionally and / or alternatively, in some embodiments, a battery charger may be enabled to obtain the temperature measurement. For example, in some embodiments, the temperature measurement may be obtained at a temperature measurement terminal of the battery pack. For example, when the battery pack is received at a device (e.g., a battery charger), the temperature measurement terminal may communicate a temperature measurement signal (e.g., a digital and / or analog signal) describing the temperature measurement to the device (e.g., a battery charger) to which the battery pack is coupled. The battery charger (e.g., a charger controller) may obtain the temperature measurement from the temperature measurement terminal.

[0061] Method 600 may include determining, at 604, that the temperature of at least one cell is between a temperature threshold lower limit and a temperature threshold upper limit, at least in part based on the temperature measurement. For example, the temperature threshold lower limit may be the temperature at which it is desired to begin reducing the battery pack current to avoid an over-temperature condition. Generally, the temperature threshold lower limit may be any suitable temperature and may be a temperature lower than (e.g., approximately 10 degrees Celsius lower than) the temperature threshold upper limit. Additionally, in some embodiments, the temperature threshold upper limit may be at a temperature upper limit, such as the temperature at which an over-temperature condition occurs. The controller may determine that the temperature of at least one cell is between the temperature threshold lower limit and the temperature threshold upper limit in any suitable manner (e.g., by threshold comparison). Additionally and / or alternatively, the determination may be performed, for example, by inputting the temperature into a mathematical model.

[0062] Additionally and / or alternatively, method 600 may include, at 606, reducing the maximum charging current in response to determining that the temperature of at least one cell is between a lower temperature threshold and an upper temperature threshold. For example, reducing the maximum charging current may include reducing (e.g., via a charging current request) the maximum charging current requested from a battery charger. According to an example aspect of the present disclosure, reducing the maximum charging current may include reducing the maximum charging current at least in part based on an inverse functional relationship between the temperature measurement and the maximum charging current. For example, the inverse functional relationship may give that the maximum charging current will decrease as the temperature of at least one cell increases. Additionally and / or alternatively, the maximum charging current may be allowed to recover (e.g., increase) as the temperature decreases (e.g., after being reduced). In some embodiments, the inverse functional relationship may be a monotonically decreasing relationship. For example, in some embodiments, the inverse functional relationship may be a linearly decreasing relationship. For example, the maximum charging current may decrease linearly with an increase in temperature. According to an example aspect of the present disclosure, other suitable functional relationships may be employed.

[0063] In some embodiments, the inverse functional relationship may be or may include a mathematical model or function. For example, a computing system may calculate the maximum charging current based on a formula or mathematical model. As another example, the inverse functional relationship may be or may include a look-up table. For example, the maximum charging current may be retrieved from a look-up table in which the temperature is provided as an input. According to an example aspect of the present disclosure, other systems suitable for leveraging the inverse functional relationship (e.g., determining thresholds) may be employed. As an example, the maximum charging current may be determined with respect to a temperature-based current limit in a temperature-current curve. The temperature-current curve may be stored in a non-transitory computer-readable medium, such as flash memory, RAM, ROM, EEPROM, hard disk memory, solid state memory, and / or any other suitable memory. For example, in some embodiments, the curve may be stored as a look-up table, a mathematical relationship or model, or other suitable representation.

[0064] In some embodiments, the maximum charging current may be based on various other current limits established based on other factors of the battery pack. For example, the (multiple) current limits may be determined according to various criteria of the battery, such as but not limited to state of charge, battery voltage, cell voltage, charging type (e.g., constant current or constant voltage), charging status, charging progress, etc. One of these current limits may be determined with respect to the temperature of the battery pack, such as based on an inverse functional relationship between the temperature and the charging current. For example, the lowest current limit may be used as the maximum charging current.

[0065] Additionally and / or alternatively, method 600 may include controlling a battery charger at 608 to charge one or more cells, at least in part, based on a maximum charge current. For example, in some embodiments, a battery charger (such as a power source of the battery charger) may be configured to provide a voltage amount and / or a current amount equal to or less than the maximum charge current to a battery pack. For example, in some embodiments, a charger controller may adjust characteristics of one or more digital signals, such as a pulse width modulation (PWM) signal, to configure the current amount and / or voltage amount and / or power amount provided by the battery charger (e.g., the power source). For example, the controller may adjust the voltage and / or current at the battery pack by adjusting the duty cycle, frequency / cycle, etc. of one or more pulse width modulation circuits at the battery charger. As another example, in some embodiments, the charger controller may adjust other components of the battery charger (such as variable components such as variable resistors, varactors, switches, etc.) to configure the current amount and / or voltage amount and / or power amount provided by the battery charger. For example, as described herein, the charger controller may be configured to adjust a power signal from the battery charger (e.g., for charging the (multiple) cells) at least in part based on the maximum charge current (e.g., from a battery controller and / or a maximum charge current determined at the charger controller).

[0066] In some embodiments, controlling the battery charger (at least in part based on the maximum charge current) may include requesting the maximum charge current from the battery charger to charge one or more cells. For example, in some embodiments, a battery controller may determine a charge current request. The charge current request may specify the amount of current requested to be provided to the battery to charge the battery, such as the maximum charge current. The charge current request may be communicated to the battery charger, such as a charger controller. In some embodiments, the maximum charge current may be requested from the battery charger periodically. For example, the maximum charge current may be determined and requested at regular intervals to ensure that the current is updated when necessary. For example, the maximum charge current may be requested at periodic intervals, such as at set time intervals (including regular intervals and / or irregular intervals), in response to a stimulus, etc.

[0067] After receiving a charging current request, the charger controller may configure a battery charger (e.g., a power source) to deliver a current amount specified by the charging current request to a battery pack (e.g., multiple cells). As an example, the battery pack and / or the battery charger may include one or more charging terminals configured to provide an electrical connection between one or more cells and the battery charger (such as between one or more cells and the power source). In some embodiments, the charging current request is transmitted to the battery charger periodically. For example, the charging current request may be transmitted at periodic intervals, such as at set time intervals (including regular intervals and / or irregular intervals), in response to a stimulus, etc.

[0068] Figure 7 FIG. 700 is a flowchart of an example method for alleviating an over-temperature situation according to an example embodiment of the present disclosure. Although, for purposes of illustration and discussion, Figure 7 the steps are depicted as being executed in a particular order, the methods of the present disclosure are not limited to the specifically illustrated order or arrangement. The various steps of method 700 may be omitted, rearranged, combined, and / or adjusted in various ways without departing from the scope of the invention.

[0069] Method 700 may be implemented by any suitable computing device that communicates with a battery pack and / or a battery charger (such as Figure 3 battery pack 320 and / or battery charger 310). As an example, some of all of the steps of method 700 may be implemented by Figure 3 battery controller 324. As another example, some or all of the steps of method 700 may be implemented by Figure 3 charger controller 314. Method 700 may be executed by any suitable computing structure, such as volatile and / or non-volatile computer-readable media, (a) processor(s), programmable logic circuits, and / or programmable logic arrays, application-specific integrated circuits, and / or other suitable computing systems.

[0070] Method 700 may include obtaining, at 702, a temperature measurement indicative of the temperature of at least one cell from a temperature sensor. The temperature measurement may indicate the temperature of the battery pack (e.g., the temperature of at least one cell). For example, in some embodiments, the temperature measurement may be transmitted from the temperature sensor to a controller such as a battery controller and / or a charger controller. In one example embodiment, a single temperature sensor is configured to obtain a temperature measurement of one cell to determine the temperature of the battery pack. For example, the temperature measurement of a single cell may be extrapolated to represent the temperature of the battery pack. According to example embodiments of the present disclosure, other suitable temperature measurement configurations may be employed.

[0071] Additionally and / or alternatively, in some embodiments, a battery charger can be enabled to obtain a temperature measurement. For example, in some embodiments, a temperature measurement can be obtained at a temperature measurement terminal of a battery pack. For example, when the battery pack is received at a device (e.g., a battery charger), the temperature measurement terminal can transmit a temperature measurement signal (e.g., a digital and / or analog signal) describing the temperature measurement to the device (e.g., a battery charger) to which the battery pack is coupled. The battery charger (e.g., a charger controller) can obtain the temperature measurement from the temperature measurement terminal.

[0072] Method 700 can include determining, at 704, that the temperature of at least one cell is above an upper temperature threshold limit, at least in part based on the temperature measurement. For example, a controller can compare the temperature of the (one or more) cells to the upper temperature threshold limit. If the temperature reaches or exceeds the upper temperature threshold limit, it may be desirable to abort charging the battery pack. For example, method 700 can include, at 706, aborting charging of the battery pack in response to determining that the temperature of one or more cells is above the upper temperature threshold limit. For example, aborting charging of the battery pack can include requesting a minimum current from the battery charger while charging is aborted. The minimum current can be a current equal to or close to zero amperes, such as a current less than about 0.1 amperes, such as 0 amperes. For example, aborting charging of the battery pack can include transmitting an abort current request to the battery charger, where the abort current request includes a request for zero amperes or close to zero amperes.

[0073] Method 700 can include determining, at 708, that the temperature of at least one cell is below a lower temperature threshold limit after aborting charging of the battery. For example, the temperature of the at least one cell being below the lower temperature threshold limit can generally indicate that charging can be safely resumed. Method 700 can include, at 710, resuming charging of the battery pack in response to determining that the temperature of one or more cells is below the lower temperature threshold limit. For example, as described herein, once the battery pack reaches the lower temperature threshold limit, the controller can re-determine the maximum charging current based on the temperature measurement.

[0074] Accordingly, the exemplary embodiments of the present invention have been described in sufficient detail. While the description refers to specific embodiments, it will be apparent to those skilled in the art that the specific details can be changed while practicing the present invention. Accordingly, the present invention should not be construed as limited to the embodiments described herein.

[0075] Although the present invention has been shown and described in detail in the drawings and the foregoing specification, it should be regarded as illustrative rather than restrictive in nature. It is to be understood that only exemplary embodiments have been shown and described and that the scope of the present invention is not limited in any way. It is understood that any feature described herein can be used with any embodiment. The illustrative embodiments are not mutually exclusive, nor do they exclude other embodiments not recited herein. Accordingly, the present invention also provides embodiments that include combinations of one or more of the above-described illustrative embodiments. Modifications and variations of the present invention as set forth herein can be made without departing from the spirit and scope of the present invention, and therefore, only such limitations as are specified in the appended claims should apply.

Claims

1. A battery pack, comprising: One or more cells; At least one temperature sensor configured to obtain a temperature measurement indicative of the temperature of at least one of the one or more cells; And A battery controller configured to control signal communication with a battery charger; Wherein the battery controller is configured to perform operations including: Obtaining the temperature measurement from the at least one temperature sensor; Determining that the temperature of the at least one cell is between a lower temperature threshold and an upper temperature threshold at least in part based on the temperature measurement; In response to determining that the temperature of the at least one cell is between the lower temperature threshold and the upper temperature threshold, reducing a maximum charging current, wherein reducing the maximum charging current includes reducing the maximum charging current at least in part based on an inverse function relationship between the temperature measurement and the maximum charging current; and Controlling the battery charger at least in part based on the maximum charging current to charge the one or more cells; The battery controller is further configured to perform operations including: Determining that the temperature of the at least one cell is higher than the upper temperature threshold at least in part based on the temperature measurement; In response to determining that the temperature of the at least one cell is higher than the upper temperature threshold, aborting charging of the battery pack; After aborting charging of the battery, determining that the temperature of the at least one cell is lower than the lower temperature threshold; and In response to determining that the temperature of the at least one cell is lower than the lower temperature threshold, resuming charging of the battery pack.

2. The battery pack according to claim 1, wherein, The inverse function relationship includes a monotonically decreasing relationship.

3. The battery pack according to claim 1, wherein, The inverse function relationship includes a linearly decreasing relationship.

4. The battery pack according to claim 1, wherein, Controlling the battery charger at least in part based on the maximum charging current includes requesting from the battery charger a maximum charging current for charging the one or more cells.

5. The battery pack according to claim 1, wherein The temperature measurement is obtained at a temperature measurement terminal of the battery pack.

6. The battery pack according to claim 1, wherein, Aborting charging of the battery pack includes requesting a minimum current from the battery charger while charging is aborted.

7. The battery pack according to claim 1, wherein, Requesting the maximum charging current from the battery charger at periodic intervals.

8. The battery pack according to claim 1, further comprising one or more charging terminals configured to provide electrical communication between the one or more cells and the battery charger.

9. The battery pack according to claim 1, wherein The battery charger includes: A power source configured to provide a power signal to the one or more cells; and A charger controller configured to adjust the power signal at least in part based on the maximum charging current.

10. The battery pack according to claim 9, wherein, The battery pack further includes one or more signal terminals configured to provide a signal connection between the battery controller and the charger controller.

11. The battery pack according to claim 9, wherein, The power source is a DC power source.

12. The battery pack according to claim 9, wherein, The power signal is a current signal.

13. The battery pack according to claim 1, wherein, The one or more cells include lithium-ion cells.

14. The battery pack according to claim 1, comprising one or more socket mechanical connectors configured to engage with one or more sockets on the battery charger to couple the battery pack to the battery charger.

15. A method for charging a battery pack while avoiding over-temperature conditions, the method comprising: Obtaining a temperature measurement value indicating the temperature of at least one cell from at least one temperature sensor; Determining that the temperature of the at least one cell is between a lower temperature threshold and an upper temperature threshold, at least in part based on the temperature measurement value; In response to determining that the temperature of the at least one cell is between the lower temperature threshold and the upper temperature threshold, reducing a maximum charging current, wherein reducing the maximum charging current includes reducing the maximum charging current at least in part based on an inverse function relationship between the temperature measurement value and the maximum charging current; and Controlling a battery charger at least in part based on the maximum charging current to charge the at least one cell; The method further comprising: Determining that the temperature of the at least one cell is higher than the upper temperature threshold, at least in part based on the temperature measurement value; In response to determining that the temperature of the at least one cell is higher than the upper temperature threshold, aborting charging of the at least one cell; After aborting charging of the battery, determining that the temperature of the at least one cell is lower than the lower temperature threshold; and In response to determining that the temperature of the at least one cell is lower than the lower temperature threshold, resuming charging of the at least one cell.

16. The method according to claim 15, wherein, The inverse function relationship includes a monotonically decreasing relationship.

17. The method according to claim 15, wherein, The inverse function relationship includes a linearly decreasing relationship.

18. The method according to claim 15, wherein, Aborting charging of the at least one cell includes requesting a minimum current from the battery charger while charging is aborted.

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