Abstract:
An information handling system battery has first and second protective circuits to detect and address faults for a first charge applied from an external power source to an integrated charger and a second charge applied from a charger of an information handling system to battery cells. If the first protective circuit detects a fault associated with the integrated charger, charging of the battery cells is still supported by inserting the battery in an information handling system. If the second protective circuit detects a fault, the battery becomes inoperative by disconnecting the battery cells. An indicator, such as LEDs on the battery casing, indicates whether a soft or hard fault has occurred.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to the field of information handling system batteries, and more particularly to a system and method for enhanced battery charge protection and fault alarm. 
     2. Description of the Related Art 
     As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems. 
     Portable information handling systems have become increasingly popular with end users due to the flexibility that portable systems provide. A portable information handling system typically includes all of the components needed to process information integrated in a small and portable housing. A typical housing has a rotationally-coupled lid that rotates from a compact closed position to an open position that exposes a keyboard and display. The housing supports processing components to process information, such as a processor and memory, which often includes wireless networking components so the end user can communicate with networks independent of a wired connections. In order to support operation of the processing components independent of a fixed power outlet, portable information handling systems typically include an integrated battery. An external adapter converts alternating current (AC) power from a power outlet to direct current (DC) power that is transmitted to the information handling system. Usually, the DC power enters at a plug exposed at the outer surface of the housing and feeds to a charger disposed within the housing. The DC power is used to power the processing components with excess power applied to charge the battery. When the plug is disconnected from the housing, the battery discharges to power the processing components. 
     One disadvantage with a conventional portable information handling system battery power architecture is that the battery must be inserted into the information handling system to charge. However, in some instances, information handling system batteries are built with a charger integrated in the battery casing so that DC power from an external adapter enters directly into the battery to allow charging of the battery independent of the information handling system. An independently chargeable battery provides greater flexibility for an end user to charge the battery without the information handling system. A battery that provides a direct plug in to charge independent of an information handling system generally must have a protection circuitry connected to the battery cells to prevent catastrophic battery failure in the event of a fault. Battery protection circuitry integrated in the battery casing typically includes a charge field effect transistor (C-FET) and a discharge FET (D-FET) that automatically disconnect the battery cells from the charger when a fault is detected. When the cells are charged, AC adapter output regulated by the charger is applied to the protection circuit and cells so that the C-FET is the only protection against excessive DC voltage being applied to the battery cells. 
     SUMMARY OF THE INVENTION 
     Therefore a need has arisen for a system and method which improves information handling system battery protection during charge. 
     In accordance with the present invention, a system and method are provided which substantially reduce the disadvantages and problems associated with previous methods and systems for charging an information handling system battery. The battery accepts a charge through first connector the provides external power to a charger integrated in the battery and having a first protection circuit or through a second connector that provides power from a charger of a device external to the battery. Power from either the first or second connector is monitored by a second protection circuit associated with battery cells of the battery. 
     More specifically, an information handling system has plural processing components integrated in a housing that cooperate to process information. The processing components are powered by an external AC adapter that converts AC power to DC power with extra power provided to a charger of the information handling system. The information handling system charger provides the extra power through an internal connector to a battery inserted in a cavity of the housing to charge the battery. When the battery is removed from the cavity, an external power source connector in the battery casing connects to the AC adapter to accept DC power directly to the battery. A charger integrated in the battery casing regulates power received directly from the AC adapter to ensure safe charging of the battery. A first protection circuit associated with the charger monitors operation of the integrated charger to detect faults so that the charger is removed from charging if a fault is detected. A second protection circuit associated with battery cells within the battery detects faults associated with the battery cells and removes the battery cells from the charging circuit if a fault is detected. A fault indicator provides a soft fault indication if the charger protection circuit detects a fault and a hard fault indication if the battery cell protection circuit detects a fault. 
     The present invention provides a number of important technical advantages. One example of an important technical advantage is that a second level of protection at the battery allows a “soft” failure from which the battery recovers when the fault is removed. For example, a soft failure that results from the charger or embedded controller integrated with the battery will prevent direct charging of the battery from an AC adapter but allow indirect charging of the battery by inserting the battery in an information handling system. LED indicators visible at the battery casing indicate soft versus hard battery failure so that an end user will know whether the battery will accept a direct charge, an indirect charge or no charge at all. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention may be better understood, and its numerous objects, features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference number throughout the several figures designates a like or similar element. 
         FIG. 1  depicts a block diagram of an information handling system having a battery with installed and separate charging capability; and 
         FIG. 2  depicts a circuit diagram of a battery having protective circuits associated with an integrated charger and internal battery cells. 
     
    
    
     DETAILED DESCRIPTION 
     An enhanced battery fault detection and alarm monitors an integrated charger of the battery in addition to battery cells to differentiate a hard battery failure from a soft failure in which the battery remains chargeable by an information handling system. For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an information handling system may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of the information handling system may include one or more disk drives, one or more network ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components. 
     Referring now to  FIG. 1 , a block diagram depicts an information handling system  10  having a battery  12  with installed and separate charging capability. Information handling system  10  has plural processing components that cooperate to process information, such as a CPU  14 , RAM  16 , a hard drive disk  18 , a chipset  20  and an embedded controller  22 . The processing components are disposed in a portable housing  24  having a rotationally coupled lid  26  that contains a display  28  for presenting processed information as visual images. Information handling system  10  is powered by an external AC adapter  30  that converts external AC voltage to DC voltage and provides the DC voltage at a power connector  32 . A charger  33  within information handling system  10  charges battery  12  with power from adapter  30  that is in excess of that needed to run the processing components. If adapter  30  is disconnected from information handling system  10 , battery  12  discharges to provide power to run the processing components. 
     Battery  12  is built in a casing  34  sized to fit in a cavity formed in housing  24  of information handling system  10 . When casing  34  is properly aligned and inserted into the cavity, an internal power connector  36  disposed at the outer surface of casing  34  couples with a connector of information handling system  10  to interface charger  33  with battery  12 . Internal power connector  36  accepts a charge that is regulated by charger  33  so that battery  12  reaches a fully charged state without damage. When casing  34  is removed from the cavity of information handling system  10 , an external power source connector  38  is exposed that accepts power from AC adapter  30 . A charger integrated in casing  34  regulates the power provided from adapter  30  to ensure that a proper charge is applied to battery  12 . 
     The integrated charger within battery  12  has an associated protection circuit that monitors for faults associated with the charger circuit. If a fault is detected, the charger circuit is disconnected from the battery cells to prevent charging by adapter  30  through external power source connector  38  and a “soft” failure indication is provided from a fault indicator  40 , such as one or more LEDs disposed in casing  34 . A soft failure indicates that charging of the battery remains possible by a reset of the charger protection circuit or by inserting battery  12  into information handling system  10 . Charging by charger  33  of information handling system  10  is monitored by a protection circuit associated with battery cells within battery  12 . If a fault is detected by a protection circuit associated with the battery cells, a “hard” failure indication is provided by fault indicators  40  indicating that battery  12  has permanently failed. A hard failure may result from chagrining through either internal power connector  36  or external power connector  38  since a hard failure is associated with a fault of the battery cells. A soft failure occurs during charging through external power source connector  38  and indicates a failure with charging circuitry integrated in battery  12  so that charging remains possible by charger  34  of information handling system  10 . In one embodiment, a battery fault interface  42  presented at display  28  receives fault indications from battery  12  to indicate soft or hard failure of a battery  12  through information handling system  10 . 
     Referring now to  FIG. 2 , a circuit diagram depicts a battery  12  having protective circuits  44  associated with an integrated charger  46  and protective circuits  50  and  52  associated with internal battery cells  48 . Protective circuit  52  is a charge field effect transistor (C-FET) that switches off power to battery cells  48  if a fault exists in the charge provided to cells  48 . Protective circuit  50  is a discharge field effect transistor (D-FET) that switches off battery cells  48  from discharging to connector  36  if a fault is detected with the discharge. A battery management unit (BMU)  54  monitors the state of battery cells  48 , much as a fuel gauge, and communicates the state of cells  48  through a management bus  56  interfaced through connector  36  with the powered device  10 , such as an information handling system. A hard failure of battery  12  occurs if either C-FET  52  or D-FET  50  detects a malfunction with battery cells  48  are permanently disconnected from internal device power connector  36  and adapter  38 . Thus, in the event of a hard failure, battery  12  cannot accept a charge for cells  48  from either internal device power connector  36  or external power source connector  38 . 
     In addition to charge protection provided by C-FET  52 , battery  12  has a second protection circuit  44  associated with charger  46  that detects, protects against and provides an alarm for faults associated with charging through external power source connector  38 . For example, a field effect transistor (FET) placed between adapter  30  and integrated charger  46  switches off in the event of a fault to prevent application of power to charger  46 . As another example, a FET placed after charger  46  switches off in the event of a fault to prevent application of power from charger  46  to cells  48 . While only one FET  44  will provide protection against faults associated with charger  46 , both FETs may be included if desired. Charger protection circuits  44  induce a soft failure of battery  12  since a fault detected by protection circuits  44  prevent charging through external power source connector  38  but do not prevent charging through internal device power connector  36 . In addition, charger protection circuits  44  induce a soft fault since circuits  44  reset once the fault is removed. An embedded controller  58 , which operates independently of BMU  54 , interfaces through management bus  56  with integrated charger  46  and BMU  54  to monitor battery operations and detect a fault that induces protection circuits  44 ,  50  and  52  to switch off. Embedded controller  58  provides intelligence with the battery for managing a charge when the battery is not inserted in the information handling system. If protective circuit  44  switches off power at charger  46 , embedded controller illuminates LED fault indicators  40  to indicate a soft fault. If protective circuits  52  or  50  switches off cells  48 , then embedded controller  58  illuminates LED fault indicators  40  to indicate a hard failure. 
     Although the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.