Battery zero voltage detection method and its application

Abstract

This specification describes battery zero voltage (0V) detection techniques and applications thereof. These techniques detect the occurrence of a 0V condition and allow the device to continue operation after one 0V condition. However, these techniques may cause the device to shut down after detecting a second occurrence of a battery 0V condition. In an embodiment, a combination of hardware and software is used on the system side of the device to detect a 0V condition and / or distinguish a 0V condition from an under-voltage protection (UVP) condition when the device is connected to an external power source.

Description

[Background technology]

[0001] Lithium-ion (Li-ion) batteries are susceptible to degradation at low voltages. Such degradation can take the form of copper dissolution and / or gas formation. Because of this susceptibility to low-voltage degradation, many systems integrate a protection integrated circuit (PIC) chip with Li-ion batteries. This chip can open a metal-oxide semiconductor field-effect transistor (MOSFET) that prevents charging if the battery cell voltage drops below 1 volt (V), for example. A battery cell voltage below 1V is called a zero-voltage (0V) state. If the battery cell voltage drops below 1V and the "0V inhibit" flag is enabled within the PIC chip, the device powered by the battery will become irrecoverable (e.g., "bricked") by the device user.

[0002] During long-term (e.g., more than a year) storage, Li-ion batteries may continue to self-discharge. Small battery cells (e.g., less than 1000 milliamps (mA)) have less capacity than larger battery cells and often discharge at a higher rate than larger battery cells. This difference in capacity means that small battery cells may experience 0V conditions during storage (e.g., storage after manufacture and before consumer use). Recent advances in battery cell chemistry mean that many Li-ion batteries can safely withstand one 0V condition and still continue to operate, but likely would not survive a second 0V condition. However, many PIC chips will not allow operation of a battery after the "0V inhibit" flag has been enabled, thus preventing further use of a battery that may still be usable. Summary of the Invention

[0003] This specification describes battery zero voltage (0V) detection techniques and their applications. These techniques detect the occurrence of a 0V condition and allow the device to continue operation after one 0V condition. However, these techniques may shut down the device after detecting a second occurrence of a battery 0V condition. In an embodiment, a combination of hardware and software is used on the system side of the device to detect a 0V condition and / or distinguish a 0V condition from an under-voltage protection (UVP) condition when the device is connected to an external power source.

[0004] In aspects, a method of managing charging events of a battery in an electronic device is disclosed. The method includes measuring a battery voltage of the battery in response to detecting an electrical connection to an external power source to initiate a charging sequence, detecting a zero voltage condition based on the battery voltage being below a first threshold voltage, incrementing an integer counter by one count in response to detecting the zero voltage condition, comparing the integer counter to a second threshold, and charging the battery if the integer counter is below the second threshold effective to allow the battery to experience at least one occurrence of the zero voltage condition. Here, incrementing the integer counter may include accessing a memory of the electronic device to increment the integer counter by one count, and the integer counter may represent a total number of occurrences of the zero voltage condition of the battery over the life of the battery. The method may also further include determining whether the total number of occurrences of the zero voltage condition of the battery is less than or equal to the second threshold. If the second threshold is one, the battery may experience one zero voltage condition. The method may further include preventing charging of the battery if the integer counter is greater than the second threshold. The method may include providing a return warranty notice to a user of the electronic device. Providing the return warranty notice may include presenting a displayable notice via a display device of the electronic device. Providing the return warranty notice may include providing an audible message to the user. The method may also include shutting down the electronic device to prevent further use of the battery after providing the return warranty notice. Additionally, in response to detecting an electrical connection to an external power source and before measuring the battery voltage, a delay may be generated before initiating a charging sequence. Also, measuring the battery voltage may include using a sensing circuit that bypasses a power path to the battery to sense the battery voltage without drawing current through the battery. In aspects, incrementing the integer counter by one count may include setting a bit in a memory of the electronic device to one.In some implementations, the method may further include triggering a zero voltage condition using a comparator circuit when a battery voltage of the battery drops below a trigger point of the comparator circuit, the trigger point being set at 1 volt.

[0005] In a further aspect, an electronic device is disclosed that includes a battery, a default charger integrated circuit configured to cause a charge delay that delays battery charging when the electronic device is electrically connected to an external power source, and a comparator circuit powered by a battery voltage of the battery. In aspects, the comparator circuit may have a trigger point that triggers when a battery voltage of the battery drops below the trigger point. The electronic device also includes a system having a processor and a memory. The system may be configured to implement a battery manager module configured to perform the aforementioned method. The electronic device may further include a cell sense line leading from the battery to the system and configured to bypass the field effect transistor and the power path to the battery.

[0006] In some aspects, another method for detecting a zero-voltage state of a battery in an electronic device is disclosed. The method includes precharging a battery using an electrical connection to an external power source, where the battery triggers an under-voltage protection state based on a battery voltage of the battery dropping below a first threshold voltage. The method further includes generating an under-voltage protection profile of the battery voltage during pre-charging of the battery based on an interaction between the protection integrated circuit, the battery, and a system of the electronic device. The method also includes mapping the under-voltage protection profile to create a signature pattern. Additionally, the method includes using one or more characteristics of the signature pattern to distinguish between an under-voltage protection state of the battery and a zero-voltage state of the battery, where the zero-voltage state is defined by a second threshold voltage that is less than the first threshold voltage of the under-voltage protection state.

[0007] In aspects, an electronic device is disclosed. The electronic device includes a battery, a sensing circuit, and a system. The sensing circuit has at least two protection integrated circuits, each having a pair of field effect transistors coupled with two body diodes to form a bidirectional power switch usable during pre-charging of the battery, and generates an under-voltage protection profile for distinguishing between an under-voltage condition of the battery and a zero-voltage condition of the battery. The system has a processor and a memory, and is configured to implement a battery manager module configured to execute the aforementioned method.

[0008] This Summary is provided to introduce a simplified concept of the battery zero voltage detection technique and its applications, which are further described below in the Detailed Description. This Summary is not intended to identify essential features of the claimed invention, nor is it intended for use in determining the scope of the claimed invention.

[0009] Details of one or more aspects of the battery zero voltage detection techniques and applications thereof are described herein with reference to the following drawings, in which like numbers are used throughout to reference like features and components: [Brief description of the drawings]

[0010] [Figure 1] 1 illustrates an example implementation of a battery zero voltage detection technique and an electronic device configured for its application in accordance with the techniques described herein. [Diagram 2] 2 illustrates an example implementation of the electronic device of FIG. 1 in more detail. [Diagram 3] 1 illustrates an example implementation of a sensing circuit having a voltage sense line that can be used to sense a battery cell voltage in accordance with the techniques described herein. [Figure 4] 1 shows a plot representing an example under-voltage protection (UVP) profile generated during pre-charging of a battery that triggered a UVP condition. [Diagram 5]FIG. 1 illustrates an exemplary method for controlling battery charging of a battery in an electronic device. [Figure 6] FIG. 1 illustrates an example method for detecting a zero voltage condition of a battery in an electronic device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] This specification describes a battery zero voltage detection technique and its application. The technique described herein enables a system to detect the occurrence of a battery 0V condition and allows for continued operation of the device after at least one occurrence of the 0V condition.

[0012] As an example, consider a battery-powered device that has sat unused in a warehouse for over two years, but is now being sold to a customer. When the customer connects the device to an external power source to charge the device's battery, the device's system wakes up and checks the battery voltage. If the battery experiences a 0V condition (e.g., due to the battery voltage self-discharging during long periods of storage), the system records a bit for this condition (or increments a counter), but still allows the battery to charge so that the customer can use the device.

[0013] As another example, an electronic device that uses both line power and battery power may experience a faster than normal rate of cell self-discharge (e.g., a failure situation). A system in the device may use line power to monitor the battery voltage and determine if a 0V condition has occurred multiple times. For example, upon detecting a second occurrence of a 0V condition, the system may (i) notify the user to return the electronic device and (ii) shut down the device to prevent further use of the battery.

[0014] As yet another example, an electronic device that uses both line power and battery power may experience a faster than normal rate of cell self-discharge, prompting the user to unplug the electronic device and connect the electronic device to an external power source to charge the battery. During charging, the system checks the battery voltage, and if the battery experiences a 0V condition, the system records a bit for this condition. The system then enables charging of the battery unless the system determines that the 0V condition has been triggered more than a threshold number of times (e.g., once, twice).

[0015] As another example, consider a battery powered device that triggers an under-voltage protection (UVP) state and shuts down the battery when it experiences a faster than normal rate of cell self-discharge and the battery voltage drops below a first threshold voltage (e.g., 2.3V, 2.5V, 2.8V, 3V). Because the battery is shut down, the system may measure the battery voltage as having no voltage, even though the battery still has some voltage (e.g., up to 3V). Thus, it may be difficult to determine whether the battery is in a safer UVP state or whether the battery voltage has dropped to a more harmful 0V state. During charging, the system maps a UVP profile and indicates whether the battery was in a 0V state based on the UVP profile. The 0V state is defined by the battery voltage being below a second threshold voltage (e.g., 0.5V, 0.75V, 1V, 1.25V, 1.5V).

[0016] Subsequently, if the UVP profile indicates a 0V condition, the system logs the bit or increments the stored value by one count. The system enables charging of the battery after one occurrence of a 0V condition (e.g., bit or stored value equal to 1). However, after a second occurrence of a 0V condition, the system notifies the user and shuts down the device. In some instances, depending on whether the battery cell chemistry can tolerate a 0V condition more than once, the system may allow the 0V condition to occur two or more times before shutting down the device.

[0017] The technology described herein allows for long-term storage of devices (e.g., in warehouses and in users' homes), allowing devices to be used longer before being recycled or discarded, thus improving sustainability and longevity. Additionally, the option of 0V detection via the system side (versus the battery pack side) enhances business flexibility by providing a good return on investment (ROI) and revenue for the product.

[0018] Although the described technical features and concepts of the battery zero voltage detection approach and its application may be implemented in any number of different environments, aspects thereof are described in conjunction with the following examples.

[0019] Exemplary Devices FIG. 1 illustrates an example implementation 100 of an electronic device configured for battery zero voltage detection techniques and applications thereof in accordance with the techniques described herein. The illustrated embodiment includes an electronic device 102 having a battery 104 that provides battery power to the electronic device 102. In some aspects, the electronic device 102 may also be electrically connected to an external power source 106 that provides line power to the electronic device 102. In one embodiment, the electronic device 102 may use line power for some functions and battery power for one or more other functions. In this manner, the battery powered functions may operate without interfering with the line powered functions. In some aspects, the coupling to the external power source 106 may be a wireless connection (e.g., using an induction coil).

[0020] The battery 104 may be any suitable rechargeable battery. The exemplary battery 104 described herein (see FIG. 2) is a Li-ion battery. Any suitable Li-ion battery chemistry may be implemented, some examples of which are described herein.

[0021] The electronic device 102 also includes a charger integrated circuit (IC) 108, a comparator circuit 110, and a battery manager module 112. The charger IC 108 is configured to create a delay between when an electrical connection to the external power source 106 is established and when charging of the battery 104 occurs. The charger IC 108 defaults to not charging and then checks the battery voltage uninterrupted via system power.

[0022] The comparator circuit 110 is configured to be powered by the battery voltage of the battery 104. In embodiments, the comparator circuit 110 has a trigger point set at a first threshold voltage (e.g., about 1 V). The comparator circuit 110 is triggered when the battery voltage drops below the trigger point.

[0023] The battery manager module 112 is configured to monitor and manage the battery 104, examples of which include controlling charging events of the battery 104, monitoring the battery state of charge (SOC), detecting a 0V condition of the battery, and enabling / disabling the battery 104 based on the number of times the battery 104 experiences a 0V condition throughout the life of the battery 104. The battery manager module 112 is configured to check the battery voltage (e.g., state of charge) and provide a notification (e.g., an alert) if it detects an issue with the battery 104. In some aspects, the battery manager module 112 can distinguish between a UVP condition 114 and a 0V condition 116 (even when the battery 104 is disabled) to determine whether the battery 104 has experienced a 0V condition 116 and / or exceeded the occurrence limit of the 0V condition 116. The UVP condition 114 is defined as the battery voltage being below a first threshold voltage (e.g., 2.3V, 2.5V, 2.8V, 3V). The 0V state 116 is defined as the battery voltage being below a second threshold voltage (e.g., 0.5V, 0.7V, 1V, 1.3V, 1.5V) that is lower than the first threshold voltage of the UVP state 114. By controlling charging events and allowing the 0V state 116 of the battery 104 to occur at least once, the battery manager module 112 can extend the life of the battery 104 and therefore extend the usefulness of the electronic device 102.

[0024] The electronic device 102 may also be configured to communicate with one or more devices or servers over a network. By way of example and not limitation, the electronic device 102 may communicate data over a local area network (LAN), a wireless local area network (WLAN), a personal area network (PAN), a wide area network (WAN), an intranet, the Internet, a peer-to-peer network, a point-to-point network, or a mesh network.

[0025] Consider now Fig. 2, which illustrates in more detail an example implementation of the electronic device of Fig. 1. The electronic device 102 of Fig. 2 is illustrated with various example devices, examples of which include a smartphone 102-1, a tablet 102-2, a laptop 102-3, a security camera 102-4, a computing watch 102-5, computing glasses 102-6, a gaming system 102-7, a video recording doorbell 102-8, and a speaker 102-9. The electronic device 102 may also include other devices, such as a television, an entertainment system, a desktop computer, an audio system, a projector, an automobile, a drone, a trackpad, a drawing pad, a netbook, an e-reader, a home security system, and other home appliances. It should be noted that the electronic device 102 may be mobile, wearable, non-wearable but mobile, or relatively stationary (e.g., desktop and home appliances).

[0026] The electronic device 102 includes a battery (e.g., battery 104). The battery 104 may be any suitable rechargeable battery. As described herein, the battery 104 may be a Li-ion battery. A variety of different Li-ion battery chemistries can be implemented, some examples of which include lithium cobalt oxide (LiCoO2), lithium iron phosphate (LiFePO4), lithium manganese oxide (LiMn2O4 spinel, or Li2MnO3-based lithium-rich layered material, LMR-NMC), lithium nickel manganese cobalt oxide (LiNiMnCoO2, Li-NMC, LNMC, NMC or NCM, and various Co stoichiometry ranges). Li-ion batteries may also include a variety of different anode materials, examples of which include graphite-based anodes, silicon (Si), graphene, and other cation intercalation / insertion / alloying anode materials.

[0027] The electronic device 102 includes one or more processors 202 (e.g., either a microprocessor, controller, or other controller). The processor 202 can process various computer-executable instructions to control the operation of the electronic device 102 and enable techniques for battery zero voltage detection techniques and their application. Alternatively or additionally, the processor(s) 202 can be implemented using any one or combination of hardware elements, firmware, or fixed logic circuitry implemented in association with processing and control circuitry. Although not shown, the electronic device 102 can include a system bus or data transfer system that couples various components within the device. The system bus can include any one or combination of various bus structures, examples of which include a memory bus or memory controller, a peripheral bus, a universal serial bus, and / or a processor bus or local bus utilizing any of a variety of bus architectures.

[0028] The electronic device 102 also includes a computer-readable medium 204 (CRM 204). The CRM 204 includes a memory medium 206 and a storage medium 208. The CRM 204 may include one or more memory devices (e.g., storage medium 208) that allow for persistent and / or non-transient data storage (as opposed to merely signal transmission), examples of which include random access memory (RAM), non-volatile memory (e.g., one or more of read-only memory (ROM), flash memory, EPROM, EEPROM, etc.), and disk storage devices. The disk storage devices may be implemented as any type of magnetic or optical storage device, examples of which include hard disk drives, recordable and / or rewritable compact discs (CDs), any type of digital versatile discs (DVDs).

[0029] The applications 210 and / or the operating system 212 implemented as computer readable instructions on the computer readable medium 204 (e.g., the storage medium 208) can be executed by the processor(s) 202 to provide some or all of the functionality described herein. The computer readable medium 204 provides a data storage mechanism for storing various device applications 210, the operating system 212, memory / storage, and other types of information and / or data related to operational aspects of the electronic device 102. For example, the operating system 212 can be maintained as a computer application in the computer readable medium 204 and executed by the processor(s) 202 to provide some or all of the functionality described herein. The device applications 210 may include a device manager, examples of which are any form of control application, software application, or signal processing and control module. The device applications 210 may also include system components, engines, or managers (such as the battery manager module 112) for implementing the battery zero voltage detection technique and techniques for its application. The electronic device 102 may include or have access to one or more machine learning systems.

[0030] Various implementations of the battery manager module 112 may include or communicate with a system on a chip (SoC), one or more integrated circuits (ICs), a processor having embedded processor instructions or a processor configured to access processor instructions stored in a memory, hardware having embedded firmware, a printed circuit board having various hardware components, or any combination thereof.

[0031] The electronic device 102 may also include a network interface 214. The electronic device 102 may use the network interface 214 to communicate data over a wired, wireless, or optical network. By way of example and not limitation, the network interface connection 214 may communicate data over a local area network (LAN), a wireless local area network (WLAN), a personal area network (PAN), a wide area network (WAN), an intranet, the Internet, a peer-to-peer network, a point-to-point network, or a mesh network. The network interface 214 may be implemented as one or more of a serial and / or parallel interface, a wireless interface, any type of network interface, a modem, or any other type of communication interface. The electronic device 102 may use the network interface 214 to communicate over cloud computing services and access platforms having resources.

[0032] The electronic device 102 also includes one or more sensors 216, which may include any of a variety of sensors, examples of which include an audio sensor (e.g., a microphone), a touch input sensor (e.g., a touch screen, a fingerprint sensor, a capacitive touch sensor), an image capture device (e.g., a camera or video camera), a proximity sensor (e.g., a capacitive sensor), a motion detection sensor (e.g., a passive infrared sensor), a temperature sensor (e.g., a thermistor), or an ambient light sensor (e.g., a photodetector). The one or more sensors 216 may also include the charger IC 108 and / or the comparator circuit 110 shown in FIG. 1.

[0033] The electronic device 102 may also include a display device (e.g., display device 218). The display device 218 may include any suitable touch-sensitive display device, such as a touch screen, a liquid crystal display (LCD), a thin film transistor (TFT) LCD, an in-place switching (IPS) LCD, a capacitive touch screen display, an organic light emitting diode (OLED) display, an active matrix organic light emitting diode (AMOLED) display, a Super AMOLED display, etc. The display device 218 may also be referred to as a display or a screen, and may display digital content on a screen.

[0034] Although not shown, the electronic device 102 also includes an I / O interface for receiving and providing data. For example, the I / O interface may include one or more of a touch-sensitive input, a capacitive button, a microphone, a keyboard, a mouse, an accelerometer, a display, a light-emitting diode (LED) indicator, a speaker, or a haptic feedback device.

[0035] These and other capabilities and configurations, and the manner in which the entities of Figures 1 and 2 function and interact, are described in more detail below. These entities may be further divided, combined, etc. The implementation 100 of Figure 1, and the detailed diagrams of Figures 2-6, illustrate some of the many possible environments, devices and methods in which the described techniques may be employed individually or in combination with one another.

[0036] FIG. 3 illustrates an exemplary implementation of a sensing circuit 300 having a voltage sense line that can be used to sense a battery cell voltage in accordance with the techniques described herein. In particular, the sensing circuit 300 is arranged to allow the system to bypass the field effect transistors (FETs) (e.g., MOSFETs) and the power path to the battery 104, thereby allowing the cell voltage to be detected without using or generating current flow. In the illustrated embodiment, the sensing circuit 300 is connected to a cell (e.g., battery 104). The sensing circuit 300 includes two protection ICs 304 (e.g., PIC 304-1, PIC 304-2), each having a pair of FETs 306 (e.g., MOSFETs). In the illustrated embodiment, the circuit 300 includes a pair of a first FET 306-1 and a second FET 306-2. The circuit 300 also includes a pair of a third FET 306-3 and a fourth FET 306-4. Each pair of FETs 306 in FIG. 3 is arranged with two body diodes 308 back-to-back to form a dual-channel MOSFET connected back-to-back to create a bidirectional power switch 310 (e.g., a first bidirectional power switch 310-1 and a second bidirectional power switch 310-2). As shown, the body diodes 308 include body diodes 308-1 and 308-2 in the first bidirectional power switch 310-1 and body diodes 308-3 and 308-4 in the second bidirectional power switch 310-2. Additionally, each power switch 310 includes two gates 312 (e.g., a first gate 312-1 and a second gate 312-2 in the first power switch 310-1, and a third gate 312-3 and a fourth gate 312-4 in the second power switch 310-2). The first gate 312-1 (and the third gate 312-3) may be a discharge field effect transistor (discharge FET), and the second gate 312-2 (and the fourth gate 312-4) may be a charge FET. Furthermore, because two protection ICs 304 are connected in series, there are two body diodes that are also connected in series. For example, body diodes 308-2 and 308-4 are in series, and body diodes 308-1 and 308-3 are in series.

[0037] The first PIC 304-1 becomes active when a UVP condition is triggered by the battery voltage dropping below a first threshold voltage (e.g., 2V, 2.3V, 2.5V, 2.8V, 3V). For example, the first gate 312-1 opens (e.g., turns off) to block the passage of electronic current through the corresponding FET 306 (e.g., first FET 306-1). However, the second gate 312-2 may still be closed (e.g., turns on), thereby allowing the battery to charge via the second FET 306-2 and the body diode 308-1. In some implementations, the second PIC 304-2 may become active as well. For example, the third gate 312-3 opens (e.g., turns off) based on a reduced battery voltage to block the passage of electronic current through the corresponding FET 306 (e.g., the third FET 306-3), while the fourth gate 312-4 remains closed (e.g., turns on) to allow the battery to charge via the fourth FET 306-4 and the body diode 308-3. Thus, when the battery voltage triggers the UVP state 114 (e.g., when the battery voltage drops below a trigger point), the battery 104 may be charged via the second gate 312-2 and the body diode 308-1, and in some implementations, may be charged via the fourth gate 312-4 and the body diode 308-3 as well. In embodiments, the first PIC 304-1 is activated before the second PIC 304-2. Alternatively, the second PIC 304-2 may be activated before the first PIC 304-1. The latency between activation of each of the first PIC 304-1 and the second PIC 304-2 may be on the order of milliseconds (ms) or seconds (s), respectively.

[0038] The sensing circuit 300 includes a positive power line 314 and a negative power line 316 connected to the positive and negative cell voltages, respectively. The sensing circuit 300 may also include a temperature sensing line 318 configured to enable measurement of the temperature of the battery 104. In embodiments, the temperature sensing line 318 is connected directly to a negative temperature coefficient (NTC) thermistor or equivalent variable thermistor of the battery 104 to measure the temperature of the battery 104.

[0039] The sensing circuit 300 also includes a first cell sense line 320 having a first high resistor 322 in-line and directly connected to the positive cell voltage of the battery 104. Additionally, the sensing circuit 300 includes a second cell sense line 324 having a second high resistor 326 in-line and directly connected to the negative cell voltage of the battery 104. The cell sense lines 320 and 324 allow the battery voltage of the battery 104 to be sensed without drawing large current through the battery 104 and using high resistors 322 and 326 configured to protect against short circuits. Additionally, electrostatic discharge (ESD) components (not shown) may be included to protect against electrical short circuits. The cell sense lines 320 and 324 also allow a more accurate reading of the battery voltage by bypassing the voltage drop from V=IR (e.g., voltage V equals current I multiplied by resistance R). For example, the sense lines 320 and 324 have a high resistance (e.g., higher than the power paths) but little to no current, resulting in a battery voltage equal to the actual cell voltage minus the IR of the power paths (or sense paths). In this case, the battery voltage is close to the actual cell voltage. In contrast, in a power path where high currents are used for both charging and discharging, any resistance in the power path (especially a high current, e.g., greater than 1 ampere (A), multiplied by a smaller resistance, e.g., 100 milliohms (mΩ)) can lead to a significant battery voltage drop, an example of which is a 0.1V drop (1A x 100mΩ) in the measurement of the battery voltage versus the actual cell voltage.

[0040] When the battery 104 voltage is at or near zero, adding a low current to charge the battery 104 causes a sudden rise (e.g., jump) in the battery system voltage. As the cell voltage rises, the FETs 306 close according to their respective UVP settings in the PIC 304, and the battery voltage aligns with the battery system voltage (including the voltage addition due to IR). For example, after the voltage jump, one FET 306 closes, then another FET 306 closes, and then the battery voltage begins to balance and a more "standard" path begins. The "standard" path indicates that the battery system voltage is substantially equal to the actual battery voltage because the high resistance / voltage path through the body diode is now through the more ideal conduction path (e.g., high conduction path) of the closed FET 306. An example of such FET interaction is shown in FIG. 4.

[0041] FIG. 4 shows a plot 400 representing an exemplary UVP profile generated during pre-charging of a battery that triggered a UVP condition. Applying a low current 402 (e.g., pre-charging) to a battery at or near zero voltage (e.g., portion 404) generates a UVP profile 406 that represents the change in the battery voltage of the battery over time. Typically, a battery at or near zero voltage experiences a rise in battery voltage as the battery 104 is charged. Using the circuit 300 of FIG. 3, applying the low current 402 causes the battery voltage to rise sharply (e.g., at 408 and portion 410) until one FET 306 closes and the voltage drops sharply (e.g., at 412), then the voltage rises again (e.g., at portion 414) until another FET 306 closes and the voltage drops sharply again (e.g., at 416). The circuit then comes to equilibrium and the voltage begins the more “standard” voltage rise path (eg, portion 418) during pre-charging of the battery 104.

[0042] The behavior near the beginning of the UVP profile (voltage curve) may provide an indication as to whether the battery 104 (immediately prior to pre-charging) was experiencing a UVP condition (e.g., between about 1V and about 3V, examples of which include 2V, 2.3V, 2.5V, and 2.8V) or a more detrimental 0V condition (e.g., <0.5V, <0.75V, <1V, <1.25V, <1.5V). For example, this FET interaction near the beginning of the UVP profile occurs significantly faster for UVP conditions than for 0V conditions. This is because the battery 104 is at a deeper voltage (e.g., <1.5V, <1.25V, <1V, <0.75V, <0.5V) in the 0V condition compared to the UVP condition, and it takes longer for the FET to close.

[0043] Thus, if the FET interaction near the beginning of the UVP profile occurs very quickly (e.g., on the order of milliseconds, examples include <10 ms, <20 ms, <30 ms, <40 ms, <50 ms), the battery 104 may have been in a UVP state. In contrast, if the FET interaction near the beginning of the UVP profile occurs more slowly (e.g., on the order of seconds, examples include between 1 and 10 seconds, between 5 and 20 seconds), the battery 104 may have been in a 0V state. Thus, observing the FET 306 close is used to indicate the timing of how deeply undervoltage the battery cell was before the pre-charge was applied, and that timing is used to distinguish between a UVP state and a 0V state.

[0044] Exemplary Methods 5 and 6 show exemplary methods 500 and 600 for battery zero voltage detection. In particular, FIG. 5 shows an exemplary method for controlling battery charging of a battery in an electronic device. FIG. 6 shows a method for detecting a zero voltage condition of a battery in an electronic device. Methods 500 and 600 can be performed by an electronic device 102 that uses a battery manager module 112 to implement the described techniques. Methods 500 and 600 collectively provide enhanced reliability and sustainability of the battery 104 and electronic device 102. Method 600 is complementary to method 500 and is optionally performed in conjunction with method 500.

[0045] Methods 500 and 600 are illustrated as a set of blocks that specify operations to be performed, but are not necessarily limited to the order or combination shown for performing the operations by each block. Furthermore, any of one or more operations may be repeated, combined, rearranged, or linked to provide a variety of additional and / or alternative methods. Portions of the following description may refer to the example implementation 100 of FIG. 1, or entities or processes detailed in FIGS. 2-4, but such references are for illustrative purposes only. These techniques are not limited to being performed by one entity or multiple entities operating on one device.

[0046] A connection to an external power source is detected at 502. For example, the charger IC 108 detects the electrical connection to the external power source 106 to initiate a charging sequence and, in response, generates a delay before enabling charging of the battery 104.

[0047] During the delay, the battery voltage is checked at 504. For example, the charger IC 108 checks the battery voltage of the battery 104 of the electronic device 102. By bypassing the power path to the battery 104 using the cell sense lines 320 and 324 in the circuit 300 of FIG. 3, the charger IC 108 senses the battery voltage of the battery 104 without drawing current through the battery 104.

[0048] At 506, the battery manager module 112 determines whether the battery voltage indicates a 0V condition. For example, if the battery voltage is detected to be below a threshold voltage (e.g., 1.5V, 1.25V, 1.0V, 0.5V, 0.25V), then the 0V condition 116 occurs. In aspects, the battery manager module 112 may check the comparator circuit 110 to detect whether the comparator circuit 110 has been triggered by the battery voltage dropping below a trigger point, which may be set to approximately 1V (e.g., 1.5V, 1.25V, 1V, 0.5V, 0.25V).

[0049] If the battery voltage does not indicate the occurrence of the 0V condition 116 ("No" at 506), then charging of the battery is enabled at 508. For example, if the battery voltage is sensed to be greater than about 1V, then the 0V condition 116 has not occurred and therefore the battery 104 may be charged. In another embodiment, if the comparator circuit 110 is not triggered, then the 0V condition 116 has not occurred and the battery 104 may be charged. If the battery voltage is greater than about 1V and less than about 3V, then the battery 104 may be experiencing the UVP condition 114 and not experiencing the 0V condition 116.

[0050] If the battery voltage indicates the 0V condition 116 ("Yes" at 506), then a bit for the 0V condition 116 is recorded at 510. For example, if the battery voltage is sensed to be less than about 1V or if the comparator circuit 110 is triggered, then the 0V condition 116 has occurred. In response, the battery manager module 112 may set the bit to 1. In one embodiment, the battery manager module 112 may increment a counter (e.g., a stored value) by 1 to track the number of occurrences of the 0V condition 116 of the battery 104. The bit and / or counter may be stored in a persistent memory on the system side. In aspects, the counter may be a bit stored in persistent storage in the memory.

[0051] At 512, the battery manager module 112 determines whether the total number of occurrences of the 0V state of the battery exceeds an occurrence threshold X. For example, the battery manager module 112 compares a bit, or a stored value, to the occurrence threshold X. In aspects, the occurrence threshold X is a positive integer (e.g., 1, 2, 3, 4). Because the occurrence threshold X is a positive integer, the battery 104 is allowed to experience at least one 0V state without becoming unrecoverable (e.g., "bricked"). Some devices may only allow one 0V state based on the cell chemistry of the battery 104, while some other batteries may be allowed to experience two, three, or more 0V states before significant damage occurs to the battery, thereby extending the usable life cycle of the battery.

[0052] If the total number of 0V conditions is less than the occurrence threshold X ("Yes" at 512), the method 500 proceeds to 508 and enables charging of the battery 104. However, if the total number of 0V conditions is greater than (or equal to) the occurrence threshold X ("No" at 512), charging of the battery is prevented at 514. For example, the battery manager module 112 determines that the battery 104 has experienced too many 0V conditions and prevents further use of the battery 104 by preventing charging of the battery 104. Too many 0V conditions may cause permanent damage to the battery 104 and make further use of the battery 104 potentially dangerous and unsafe.

[0053] The user is notified of the return material authorization (RMA) at 516 and the device is shut down (e.g., the battery 104 is disabled). For example, line power from the external power source 106 may be used to present a notification to the user via the display device 218 of the electronic device 102 informing the user that the battery 104 is no longer usable and that the user should return the electronic device 102. In another embodiment, the notification may be sent to another device associated with the user. In aspects, the notification may be an audible tone, a voice recording, a text message, etc. The electronic device 102 may then be shut down to prevent potential use of the battery 104.

[0054] 6 illustrates a method 600 for detecting a zero voltage condition of a battery in an electronic device. The method 600 may be performed by the electronic device 102 using the charger IC 108, the comparator circuit 110, and the battery manager module 112.

[0055] A connection to an external power source is detected at 602. For example, the charger IC 108 detects the electrical connection to the external power source 106 and, in response, generates a delay before enabling charging of the battery 104.

[0056] During the delay, the battery voltage is checked at 604. For example, the charger IC 108 checks the battery voltage of the battery 104 of the electronic device 102. In some instances, the battery voltage may be measured as 0V even though the battery 104 may still have minimal charge (e.g., greater than 0V but less than 3V).

[0057] Pre-charging of the battery is enabled at 606. For example, the battery 104 may be charged at a low current (e.g., a charge rate of C / 50 or less) to minimize or reduce potential damage to the battery 104.

[0058] A UVP profile for the battery is generated at 608. For example, the battery manager module 112 monitors the battery voltage during pre-charging of the battery 104 and maps the battery voltage to generate a UVP profile (e.g., UVP profile 406 of FIG. 4). Thus, the UVP profile is a voltage curve (e.g., change in battery voltage over time) based on applied current for a battery having a battery voltage below a threshold voltage (e.g., <3V) defined by the UVP condition. In some cases, a battery may have a battery voltage that is zero voltage or close to zero voltage. The UVP profile may be used to distinguish between the 0V state 116 and the UVP state 114, such as when an initial battery voltage measurement is unreliable. In embodiments, one or more signature patterns in the UVP profile are evaluated to identify the likelihood of the UVP state 114 versus the 0V state 116. The signature pattern is a portion of the voltage curve that indicates a voltage change behavior that indicates a particular low-voltage state of the battery (e.g., the UVP state 114 or the 0V state 116) when the battery is charged. 4, the signature pattern may be identified as abrupt spikes and drops in voltage representative of FET interaction (e.g., closing FET 306) as current is applied to the battery. In one embodiment, one or more characteristics (e.g., timing) of the signature pattern are used to indicate whether the battery 104 is likely to be in the 0V state 116 or the UVP state 114.

[0059] At 610, the battery manager module 112 determines whether the UVP profile indicates the occurrence of a 0V condition. For example, when a pre-charge current is applied to the battery 104, the battery manager module 112 analyzes the timing of the interaction of the FETs (e.g., the closing of the two series-connected body diodes 308).

[0060] If the FET interaction occurs relatively slowly (e.g., on the order of a few seconds), the battery manager module 112 determines that a 0V condition has occurred ("Yes" at 610). Because the battery has experienced a 0V condition 116, the method 600 proceeds to "A" at 510 of FIG. 5 to record the 0V condition 116 bit and to further determine whether to enable or prevent charging of the battery 104 based on the number of occurrences of the 0V condition 116.

[0061] Returning to 610, if the FET interaction occurs relatively quickly (e.g., on the order of a few milliseconds), the battery manager module 112 may determine that the UVP profile 406 indicates a UVP condition 114 and not a 0V condition 116 ("No" at 610). Because the battery 104 is not experiencing the 0V condition 116, the method 600 proceeds to "B" to 508 of FIG. 5 to enable charging of the battery 104.

[0062] Several examples are described below. 1. A method for detecting a zero voltage condition of a battery in an electronic device, the method comprising: measuring a battery voltage of the battery in response to detecting an electrical connection to an external power source to initiate a charging sequence; detecting the zero voltage condition based on the battery voltage being below a first threshold voltage; incrementing an integer counter by one count in response to detecting the zero voltage condition; comparing the integer counter to a second threshold; and charging the battery if the integer counter is below the second threshold enabling allowing the battery to experience at least one occurrence of the zero voltage condition.

[0063] Incrementing the integer counter may include accessing a memory of the electronic device to increment the integer counter by one count, and the integer counter may represent a total number of occurrences of a zero voltage condition of the battery over the life of the battery.

[0064] The method may further include determining that a total number of occurrences of a zero voltage condition for the battery is less than or equal to a second threshold.

[0065] The second threshold may be 1, which enables allowing the battery to experience a zero voltage condition once.

[0066] The method may further include preventing charging of the battery if the integer counter is greater than a second threshold.

[0067] The method may further include providing a return policy notice to a user of the electronic device.

[0068] Providing the return authorization notice may include presenting a notice viewable via a display device of the electronic device.

[0069] Providing a return warranty notification may include providing an audible message to the user.

[0070] The method may further include, after providing a return authorization notice, shutting down the electronic device to prevent further use of the battery.

[0071] The method may further include, in response to detecting an electrical connection to the external power source and prior to measuring the battery voltage, generating a delay before initiating a charging sequence.

[0072] Measuring the battery voltage may include using a sensing circuit that bypasses the power path to the battery to sense the battery voltage without drawing current through the battery.

[0073] Incrementing the integer counter by one count may include setting a bit in a memory of the electronic device to one.

[0074] The method may further include triggering a zero voltage condition using a comparator circuit when a battery voltage of the battery drops below a trigger point of the comparator circuit, the trigger point being set to 1 volt.

[0075] An electronic device comprising: a battery; a default charger integrated circuit configured to cause a charge delay that delays charging of the battery when the electronic device is electrically connected to an external power source; a comparator circuit powered by a battery voltage of the battery and having a trigger point that triggers when the battery voltage of the battery drops below the trigger point; and a system having a processor and memory, the system implementing a battery manager module configured to perform the method disclosed above.

[0076] The electronic device may further include a cell sense line leading from the battery to the system and configured to bypass the field effect transistor and the power path to the battery.

[0077] 1. A method for detecting a zero-voltage condition of a battery in an electronic device, the method comprising: pre-charging a battery using an electrical connection to an external power source, the battery triggering an under-voltage protection condition based on a battery voltage of the battery dropping below a first threshold voltage; generating an under-voltage protection profile of the battery voltage while pre-charging the battery based on interactions between a protection integrated circuit, the battery, and a system of the electronic device; mapping the under-voltage protection profile to create a signature pattern; and using one or more characteristics of the signature pattern to distinguish between an under-voltage protection condition of the battery and a zero-voltage condition of the battery, the zero-voltage condition being defined by a second threshold voltage that is less than the first threshold voltage of the under-voltage protection condition.

[0078] The method may further include accessing a memory of the electronic device to increment a counter based on a determination that the battery is in a zero voltage condition, and determining a total number of occurrences of the zero voltage condition of the battery over the life of the battery based on the counter.

[0079] The method may further include determining that a total number of occurrences of a zero voltage condition for the battery is less than or equal to a threshold number, and in response to the determination, enabling charging of the battery.

[0080] The threshold number may be 1, which is effective to allow the battery to experience a zero voltage condition once.

[0081] The method may further include determining that the counter exceeds a threshold number, and in response to determining that the counter exceeds the threshold number, preventing charging of the battery.

[0082] The method may further include providing a return policy notice to a user of the electronic device.

[0083] Providing the return authorization notice may include presenting a notice viewable via a display device of the electronic device.

[0084] Providing a return warranty notification may include providing an audible message to the user.

[0085] The method may further include shutting down the electronic device to prevent further use of the battery after providing a return authorization notice.

[0086] The threshold number may be a positive integer. The one or more characteristics may include a timing of an interaction of a field effect transistor (FET) during pre-charging of the battery, and the interaction of the FET may include closing at least two series connected body diodes.

[0087] The method may further include determining that the battery is in an under-voltage protection state based on a timing of the FET interaction being less than 50 milliseconds.

[0088] The method may further include determining that the battery is in a zero voltage state based on a timing of the FET interaction being between 1 second and 20 seconds.

[0089] The method may further include triggering a zero voltage condition using a comparator circuit when the battery voltage drops below a trigger point of the comparator circuit, the trigger point being set to 1 volt.

[0090] 1. An electronic device comprising: a battery; a sensing circuit having at least two protection integrated circuits, each having a pair of field effect transistors coupled with two body diodes to form a bidirectional power switch usable during pre-charging of the battery and generating an under-voltage protection profile for distinguishing between an under-voltage condition of the battery and a zero-voltage condition of the battery; and a system having a processor and memory, the system configured to implement a battery manager module configured to perform the method disclosed above.

[0091] A computer-readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to perform the methods disclosed above.

[0092] The electronic device includes a battery, a system having a processor and a memory, a default charger integrated circuit configured to cause a charge delay that delays battery charging when the electronic device is electrically connected to an external power source, a comparator circuit powered by a battery voltage of the battery, the comparator circuit having a trigger point set at approximately 1 volt and configured to increment a counter in the memory of the system in response to the trigger point being triggered by the battery voltage dropping below the trigger point, and a cell sense line conducted from the battery to the system and configured to bypass the field effect transistor and the power path to the battery.

[0093] The zero voltage condition may be a battery voltage below 1 volt. In some implementations. Additionally or alternatively, in some of these implementations, the under-voltage protection condition may be a battery voltage between 1 volt and 3 volts.

[0094] The cell sense lines may be connected to the positive and negative terminals of the battery with high resistance paths. The counter may be a bit saved in permanent storage in memory.

[0095] The processor may be configured to execute instructions in the memory to determine the current flowing into the battery and the timing to effect opening or closing of the MOSFET during pre-charging of the battery, to create a profile from readings of the timing of the current into the battery, and to indicate, based on the profile, that the battery has experienced a zero voltage condition.

[0096] conclusion Although aspects of the battery zero voltage detection technique and its application have been described in configuration and / or method specific language, the subject matter of the appended claims is not necessarily limited to the particular configurations or methods described. Rather, the particular configurations and methods are disclosed as exemplary implementations of techniques for the battery zero voltage detection technique and its application, and other equivalent configurations and methods are intended to be within the scope of the appended claims. Moreover, a variety of different aspects have been described, and it should be understood that each described aspect can be implemented independently or in conjunction with one or more of the other described aspects.

Claims

1. 1. A method for controlling charging events of a battery in an electronic device, comprising: measuring a battery voltage of the battery in response to detecting an electrical connection to an external power source to initiate a charging sequence; detecting a zero voltage condition based on the battery voltage being below a first threshold voltage; incrementing an integer counter by one count in response to said detecting said zero voltage condition; comparing the integer counter to a second threshold; charging the battery when the integer counter is below the second threshold enabling the battery to experience at least one occurrence of the zero voltage condition.

2. incrementing the integer counter includes accessing a memory of the electronic device to increment the integer counter by one count; The method of claim 1 , wherein the integer counter represents a total number of occurrences of the zero voltage condition of the battery over the life of the battery.

3. The method of claim 2 , further comprising determining that the total number of occurrences of the zero voltage condition of the battery is less than or equal to the second threshold.

4. The method of any one of claims 1 to 3, wherein the second threshold is one effective to allow the battery to experience the zero voltage condition one time.

5. 3. The method of claim 1 or claim 2, further comprising preventing the charging of the battery if the integer counter is greater than the second threshold.

6. The method of claim 5 , further comprising providing a return policy notice to a user of the electronic device.

7. The method of claim 6 , wherein providing the return authorization notice comprises presenting a notice viewable via a display device of the electronic device.

8. The method of claim 6 , wherein providing the return authorization notification comprises providing an audible message to the user.

9. The method of any one of claims 5 to 8, further comprising shutting down the electronic device after providing the return warranty notice to prevent further use of the battery.

10. 10. The method of claim 1, further comprising: in response to the detection of the electrical connection to the external power source and prior to measuring the battery voltage, generating a delay before initiating the charging sequence.

11. 11. The method of claim 1, wherein measuring the battery voltage includes using a sensing circuit that bypasses a power path to the battery to sense the battery voltage without drawing current through the battery.

12. The method of any one of claims 1 to 11, wherein incrementing the integer counter by one count comprises setting a bit in a memory of the electronic device to one.

13. 13. The method of any one of claims 1 to 12, further comprising triggering the zero voltage condition using a comparator circuit when the battery voltage of the battery drops below a trigger point of a comparator circuit, the trigger point being set to 1 volt.

14. 1. An electronic device comprising: Batteries and a default charger integrated circuit configured to cause a charge delay that delays battery charging when the electronic device is electrically connected to an external power source; a comparator circuit powered by a battery voltage of the battery and having a trigger point that triggers when the battery voltage of the battery drops below the trigger point; a system having a processor and a memory; The system is an electronic device configured to implement a battery manager module configured to perform the method according to any one of claims 1 to 13.

15. 15. The electronic device of claim 14, further comprising a cell sense line routed from the battery to the system and configured to bypass a field effect transistor and a power path to the battery.

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