Battery management apparatus for portable electronic devices

A battery management system can have a portable electronic device for providing electrical therapy to the body of a patient responsive to the occurrence of a treatable condition. The portable device can have a rechargeable battery, memory, data processor for determining available operating time for the portable device prior to recharging, and a display panel, or alarm, to inform the patient of, inter alia, available operating time. The portable device data processor can obtain and record data regarding the patient, the battery, and the portable device operational status. The battery management system can also include a rechargeable "smart battery," of known design, which has an integral processor and memory capable of monitoring and updating the status and condition of the battery. The portable electronic device can communicate with and update the operational characteristics stored by the smart battery. The smart battery can be recharged using an appropriate conventional recharger. The portable electronic device can include battery maintenance capabilities to perform tests on the smart battery to independently evaluate the condition thereof. The portable electronic device can also have a battery status monitoring circuit which can monitor the battery condition independently of the smart battery internal monitoring system. The portable electronic device can further include a converter-defibrillator.

BACKGROUND OF THE INVENTION 
 1. Field of the Invention 
 The present invention relates generally to portable electronic devices 
 which utilize batteries. More particularly, the present invention relates 
 to portable medical devices. Still more particularly, the present 
 invention relates to methods and apparatus for the maintenance and 
 management of the batteries of such portable medical devices. 
 2. Description of the Prior Art 
 Battery management is a concern in any portable electronic device, but is a
 primary concern in portable medical devices. The need for more 
 comprehensive battery maintenance in portable and implantable medical 
 devices has been noted, for example, in U.S. Pat. No. 4,080,558 to 
 Sullivan, U.S. Pat. No. 5,411,537 to Munshi, et. al., U.S. Pat. No. 
 5,483,165 to Cameron, et. al., and U.S. Pat. No. 5,470,343 to Fincke, et. 
 al. 
 A defibrillator is a device capable of delivering a preset amount of 
 electrical energy to a patient's heart for the purpose of terminating an 
 arrhythmia. For portable defibrillators, batteries are used to provide the
 electrical energy delivered. Historically, portable defibrillator 
 maintenance has been problematic due to insufficient means to ensure 
 comprehensive management of the batteries. As portable medical devices are
 intended for relatively long-term monitoring and, in the case of portable 
 defibrillators, intended for therapeutic shock delivery for patients at 
 risk from sudden cardiac death due to tachyarrhythmias, a comprehensive 
 battery management program is essential. 
 Historically portable defibrillator design has been concerned with ensuring
 that the devices function properly when needed. Problems may arise if the 
 batteries of the defibrillators are at less than full capacity or are worn
 out or are accidentally taken off their chargers so that the batteries are
 nonfunctional. 
 Therefore, there is a need in the portable electronic device industry, and,
 in particular, in the portable medical electronic device industry to 
 implement a comprehensive way of informing the patient, as precisely as 
 possible, of the status of that patient's device, and particularly the 
 status of the device battery. This status should include not only the 
 current conditions of the device battery but also other information, such 
 as an indication of how much time remained in which the device would be 
 operable. 
 SUMMARY OF THE INVENTION 
 The present invention is preferably utilized in connection with a 
 patient-worn energy delivery system for imparting electrical therapy to 
 the body of a patient responsive to an occurrence of a treatable 
 condition. The present invention is designed to constantly monitor and 
 comprehensively inform the patient of the condition of the device, and 
 particularly the condition of the device battery. 
 The system includes a monitor-defibrillator worn by the patient. The 
 monitor-defibrillator monitors the patient's ECG to detect life 
 threatening arrhythmias and delivers a cardioverting or defibrillating 
 shock if needed. The monitor-defibrillator records system operational 
 information and ECG signal data. Periodically the patient is required to 
 off-load this information to a patient base station. This is accomplished 
 when the monitor-defibrillator is connected to a patient base station at 
 the time battery charging is initiated. Thus, the patient base station is 
 coupled with the monitor-defibrillator for periodic battery charging, 
 device maintenance and the offloading of data. When a 
 monitor-defibrillator is inserted into the monitor interface connector, 
 the patient base station retrieves battery status from the monitor. The 
 patient base station analyzes this information and may schedule 
 maintenance operations or patient notifications if certain conditions are 
 met. 
 The primary functions performed by the patient base station are providing 
 data communication interfaces to the various components of the system, 
 battery pack charging and maintenance, monitor-defibrillator maintenance, 
 monitor-defibrillator data retrieval and storage, facilitating 
 monitor-defibrillator initialization via the physician programming console
 and providing visual and audible feedback for patient interactions. 
 The patient base station provides means to simulate the operation of 
 various monitor-defibrillator and electrode harness hardware functions. 
 These enable the patient base station to verify that the 
 monitor-defibrillator and the electrode harness hardware is functioning 
 properly. 
 A physician programming console is also utilized, which is an IBM PC-AT 
 compatible computer. The physician programming console facilitates 
 programming of the patient base station and the monitor-defibrillator. 
 Also included is an electrode harness, worn by the patient on the chest, 
 which contains electrodes for sensing ECG signals from the heart and large
 surface area electrodes for delivering therapy pulses to the heart in the 
 event of the occurrence of a treatable arrhythmia. 
 The monitor-defibrillator indicates the future time or activity level 
 remaining at which the device could operate. The apparatus considers the 
 rates of discharge and the rates of use and the amount of energy taken out
 of the battery. The device also monitors the number of charge cycles on 
 the battery, the date when the battery was installed and other pertinent 
 information such as battery pack expiration parameters. 
 The monitor-defibrillator itself includes circuitry to monitor the capacity
 of the battery. Thus, if the monitor-defibrillator undergoes some kind of 
 abnormality, for example, some component begins drawing more current than 
 the normal average current of the device, the circuit will detect the 
 abnormality and the current will trip a comparator. The comparator alerts 
 the computer and the remaining run time of the battery pack will be 
 adjusted accordingly and can be displayed to the patient. 
 The patient base station also periodically performs a capacity check on the
 monitor-defibrillator when the monitor-defibrillator is coupled to the 
 patient base station during charging and maintenance operations. This is a
 more comprehensive check than the one performed internal to the 
 monitor-defibrillator. The patient base station can discharge the battery 
 fully, charge it up fully and then discharge the battery. The current 
 that's being discharged is precise, thus, over a period of time the 
 processor could calculate whether the actual capacity of the battery is 
 meeting the specifications. Factors such as the amount of charge and the 
 rate of discharge are considered. 
 Having the capability to perform the monitoring functions on the 
 monitor-defibrillator rather than solely at some remote base station is 
 beneficial because the battery is necessarily contained in the 
 monitor-defibrillator or attached to it via an electrical connector. Thus,
 if the patient has traveled away from the base station, that patient would
 have to return to the base station to be certain that sufficient capacity 
 remained in the battery. 
 Alternatively, the monitor-defibrillator could itself be designed with 
 additional functionality to perform all of the heretofore mentioned 
 functions of the patient base station except, preferably, for the battery 
 recharging function. In such a system, the battery can be a "smart" 
 battery which has an internal memory/processor that can monitor and store 
 information regarding the status of the battery. In this system, a 
 dedicated battery recharger, also having a processor which communicates 
 with the memory/processor in the smart battery can be utilized which does 
 not require the functional capability of a patient base station. The smart
 battery memory/processor also communicates with the monitor-defibrillator 
 when it is connected thereto. 
 Furthermore, although the smart battery can have the capability to monitor 
 and determine operational characteristics thereof, it can be desirable 
 that the monitor-defibrillator also independently, and more precisely, 
 monitor the condition of the smart battery, particularly, for example, 
 during a rapid drain condition as when electrical energy is being 
 delivered to a patient when treatment is required. It is very important 
 for the monitor-defibrillator to very precisely monitor the battery 
 condition to ensure that a sufficient energy supply remains in the 
 battery. Typically, the smart battery only monitors the data 
 storage/processor circuitry of the monitor-defibrillator and not the 
 converter. Thus, the monitor-defibrillator uses this added information to 
 update the memory/processor in the smart battery. 
 These and other objects and advantages of the invention will become 
 apparent from the following description of certain present preferred 
 embodiments taken in conjunction with the appended claims and the attached
 drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
 An apparatus is provided for monitoring and supporting the 
 monitor-defibrillator electronics and the rechargeable battery pack 
 provided therein. The system 10 of the present invention is shown 
 schematically in FIG. 1. As can be seen from FIG. 1, the present system 10
 involves a number of interrelated components. A monitor-defibrillator 12 
 is included which is operatively connectable via an interface module 26, 
 to either a patient base station 30 or an electrode harness 66 having two 
 groups of electrodes 14, 16. A group of delivering electrodes 14 is 
 provided for delivering a cardioverting or defibrillating shock when 
 necessary to a patient. Another group of electrodes 16 performs sensing 
 operations in which the physiological condition of a patient may be 
 monitored. The delivering electrodes 14 are operatively connected to a 
 converter-defibrillator 19 located within the monitor-defibrillator 12. 
 The electrode harness 66 also includes a patient display 24 with the 
 capability of displaying visual messages, enunciating audio messages and 
 activating audio alarms. The patient display 24 also includes various 
 buttons for providing the patient with a means of input to the device. The
 operation of the electrode harness/monitor-defibrillator are more 
 particularly described in co-pending application Ser. No. 08/651,274, 
 assigned to the present assignee and hereby incorporated by reference 
 herein. 
 The battery pack 18 is responsible for providing the necessary power to 
 operate the converter-defibrillator circuitry for delivering the 
 cardioverting or defibrillating shock. Therefore, it is important that the
 energy capacity of battery 18 be ensured. The monitor-defibrillator 12 
 preferably utilizes a high-energy-density nickel-cadmium battery. 
 Preferably, the battery is comprised of five 1.2 volt cells connected in 
 series to yield six volts. 
 The monitor-defibrillator 12 also includes battery control circuitry 20 
 which can activate the battery 18 to deliver its charge to the 
 converter-defibrillator 19 and subsequently to the delivery electrodes 14 
 when necessary. The battery control circuitry 20 is responsive to certain 
 data conditions of the patient. For this reason, the battery control 20 is
 operatively connected to data storage/processor 22, also located within 
 the monitor-defibrillator 12. The data storage/processor 22 receives data 
 from the sensing electrodes 16. The data storage/processor 22 in the 
 monitor-defibrillator preferably utilizes non-volatile memory. The data 
 storage/processor 22 stores programmable system operational parameters, 
 system operating status information, digitized ECG episodes and the 
 results of hardware diagnostic tests. This data, through subsequent 
 analysis, provides the means to allow reconstruction of ECG events and 
 analysis of device performance. 
 The monitor-defibrillator 12 is able to perform various system and battery 
 checks. Energy usage of the monitor-defibrillator 12 is monitored in real 
 time to determine the useful energy remaining of the battery 18 per 
 charge. The patient display 24 located on the electrode harness 66 
 indicates the operating time remaining for the battery 18. The patient may
 access this function at any time by pressing a button on the patient 
 display 24. The run-time parameter is available to an external host via 
 the communications interface located in the interface module 26. A low 
 battery condition as determined by the monitor-defibrillator 12 is 
 recorded in non-volatile memory of the data storage/processor 22. The 
 patient is also alerted to a low battery condition by the patient display 
 24. 
 The monitor-defibrillator 12 monitors the battery current consumption and, 
 if required, makes an appropriate adjustment to the battery run-time 
 parameter based on sampling the real-time monitor-defibrillator current 
 consumption. The current is monitored by an analog circuit in the 
 monitor-defibrillator 12 and is input into a comparator at a trip level of
 current. The voltage is monitored but is not sent to the comparator. The 
 trip level is a level of current that is based on a precalculated worst 
 case (i.e., maximum) average current developed for the device. For the 
 particular hardware used with the present invention, the amount of typical
 maximum run current (i.e., the trip level current) is 74 milliamps. If the
 measured current exceeds the trip level, the comparator trips and the 
 analog to digital converter in the data storage/processor 22 is commanded 
 to read the analog representation of the current that is being drawn by 
 the monitor-defibrillator 12. The monitor-defibrillator 12 measures the 
 time period of excessive current draw and the amount of current above the 
 trip level. Based on the measured readings, time is deducted from the 
 battery runtime parameter by the monitor-defibrillator. The updated 
 runtime remaining may be accessed by the patient at any time, as discussed
 above. 
 As long as the actual, measured current of the monitor-defibrillator 12 is 
 less than the trip level current, the data storage/processor 22 presumes 
 that the actual current is the same as the trip current when deducting 
 time from the battery runtime parameter. Thus, although the typical 
 maximum run current is provided as 74 mils, the battery 18 is nearly 
 always providing a current below 74 milliamps. 
 The patient has the capability to access buttons on the patient display 24 
 that when activated will cause the remaining run time to be indicated. If 
 a patient is very active so as to cause one of the sensing electrodes 16 
 to have fallen off or otherwise become disconnected from the patient, an 
 alarm is sounded. The activation of this alarm also utilizes energy which 
 will be subtracted from the run time. 
 The current measuring capability of the monitor-defibrillator 12 does not 
 include current drawn by the converter-defibrillator 19. The 
 monitor-defibrillator 12 tracks the periods when the 
 converter-defibrillator 19 is actively drawing current from the battery 18
 and makes adjustments to the battery run time to compensate for the energy
 loss. 
 The monitor-defibrillator 12 also makes adjustments for depletion of 
 battery 18 capacity during periods when the device is not being used. When
 not in use (such as when stored on a shelf or taken by the patient on a 
 day's outing as a spare device) the monitor-defibrillator 12 will 
 automatically power itself up at specified intervals and make adjustments 
 to the battery run time to compensate for energy losses due to 
 self-discharge of the battery and current draw of monitor-defibrillator 12
 components when powered down. 
 The monitor-defibrillator 12 will utilize measures intended to reduce 
 depletion of battery 18 capacity in order to maximize available energy if 
 a treatment pulse is required. The monitor-defibrillator 12 will be 
 optimized to execute its monitoring functions as rapidly as possible and 
 then enter a low power operating mode until the monitoring functions must 
 again be executed. The monitor-defibrillator can be kept in a low power 
 operating mode when not performing necessary system operating functions. 
 Additionally, when possible, high current devices will be powered down 
 after completing their required tasks. An example would be the analog to 
 digital converter. By scheduling analog to digital conversion readings at 
 the beginning of monitoring functions, the analog to digital converter can
 be powered down sooner than if analog to digital readings are interspersed
 throughout the monitoring functions. 
 If the run time parameter indicates that the depletion of battery 18 
 capacity has reached the level at which the battery 18 should be recharged
 utilizing the patient base station 30, then the patient display 24 will 
 provide notification. The notification will consist of visual and/or audio
 indicators. The notification will require acknowledgment by the patient 
 before it will be discontinued. The notification will be repeated at 
 predetermined intervals, for example, every 15 minutes, until the battery 
 18 is recharged by the patient base station 30. The monitor-defibrillator 
 12 can also determine the available device operating time (prior to 
 recharging the battery), taking into account at least: (1) adjustments for
 abnormally high current draw of the device including adjustments for 
 converter operation or operation of other high current draw devices as 
 well as adjustments for excessive current draw from a defective component;
 (2) adjustments for normal current draw during an elapsed time period; (3)
 adjustments for device fault conditions such as failure of a battery load 
 test or a problem with operation of the converter; and (4) adjustments for
 depletion of battery capacity during periods of non-use. The patient 
 display 24 or alarms can be used to notify the patient of the available 
 device operating time. 
 The monitor-defibrillator 12 will also utilize an analog to digital 
 converter located in the data storage/processor 22 to supervise the 
 battery 18 voltage during operation of the converter-defibrillator 19. The
 converter-defibrillator 19 may be operated in either a fast charge mode or
 a slow charge mode. The fast charge mode minimizes the time to charge the 
 converter-defibrillator 19 but at a maximized current draw from the 
 battery 18. The slow charge mode minimizes the capacitor charging current 
 but with an increased time to charge the converter-defibrillator 19. The 
 converter-defibrillator 19 is normally operated in fast charge mode. 
 If the battery 18 voltage falls below a level at which the 
 monitor-defibrillator 12 can reliably operate the converter-defibrillator 
 19, then the monitor-defibrillator 12 will switch the 
 converter-defibrillator 19 to a slow charge mode. This will permit the 
 battery 18 voltage level to recover to a level at which the 
 monitor-defibrillator 12 can again reliably operate the 
 converter-defibrillator 19. Use of the slow charge mode permits the 
 converter to be operated and a therapy pulse delivered to the patient when
 the battery 18 capacity is low. 
 If during operation of the converter-defibrillator 19 in the slow charge 
 mode the battery 18 voltage falls below a level at which the 
 monitor-defibrillator 12 can reliably operate the converter-defibrillator 
 19, then the monitor-defibrillator 12 will deactivate the converter and 
 evaluate the energy capability stored in the converter. If the energy 
 stored in the converter is sufficient to deliver at least a minimal energy
 pulse, such as, for example, 30 joules, then the treatment cycle will 
 continue with delivery of the available energy. If there is not enough 
 energy stored in the converter to deliver a minimal energy pulse, then the
 converter will be discharged. In addition, notification will be given 
 using the patient display 24 that the device is disabled and medical 
 assistance should be provided to the patient. 
 If the monitor-defibrillator 12 determines that the battery 18 capacity has
 fallen below a level at which the system performance data is in danger of 
 being corrupted then the monitor-defibrillator 12 will remove operating 
 power. The removal of operating power will reserve the remaining battery 
 18 capacity for maintenance of the data storage/processor 22. The 
 integrity of the data storage is essential to evaluating the proper 
 operation of the device. Since this low level of battery 18 capacity is 
 inadequate for reliable operation of the monitor-defibrillator, the best 
 possible use of the remaining battery 18 capacity is to preserve the 
 operational history of the device stored in the data storage/processor 22.
 When this state has been reached, the monitor-defibrillator will refuse to
 power up until connected to the patient base station 30. If required, the 
 patient base station 30 will provide additional energy to the 
 monitor-defibrillator 12 to insure proper functioning during this power up
 sequence. The patient base station will then retrieve the operational 
 history from the monitor-defibrillator 12 and recharge the battery 18. 
 The analog to digital converter located in the data storage/processor 22 is
 powered up each interim cycle to sample the analog inputs. This interim 
 cycle is preferably every 5 milliseconds, which generally corresponds to 
 the ECG sampling rate. After sampling the analog inputs, the analog to 
 digital converter is powered down to conserve battery power. There are 
 entire portions of the monitor-defibrillator 12 that periodically go into 
 a low current sleep mode. 
 On a routine basis the patient is required to couple the 
 monitor-defibrillator 12 with the patient base station 30 (see FIG. 4). 
 When the monitor-defibrillator 12 is removed from the electrode harness 66
 and inserted in the receptacle 31 of the patient base station, connection 
 is made between the monitor-defibrillator interface 26 and a 
 monitor-defibrillator interface 32 located within the patient base station
 30. The patient base station monitor-defibrillator interface 32 is thus 
 operatively connected to the data storage/processor 22 of the 
 monitor-defibrillator 12. In this way, the monitor-defibrillator interface
 32 can download information from the memory of the data storage/processor 
 circuitry 22; i.e., information, that was received from both the sensing 
 electrodes 16 regarding the patient's physiological data, and also from 
 the battery control circuitry 20 regarding the operating history of the 
 monitor-defibrillator 12. 
 The monitor-defibrillator interface 32 of the patient base station 30 is 
 also operatively connected to the battery 18. In this way, the patient 
 base station 30 can perform comprehensive tests as to the operating 
 parameters of the battery 18. Further, charging of the battery 18 can also
 be performed through the monitor-defibrillator interface 32. The battery 
 18 of each monitor-defibrillator 12 requires periodic charging. Thus, 
 monitor-defibrillators 12 that are not in use are to be stored on a 
 patient base station charging port (i.e., coupled to the 
 monitor-defibrillator interface 32), where they undergo charging and 
 maintenance operations. The patient base station 30 provides battery 
 status information to the patient by way of a visual display including 
 indicator lights as well as by audio alarms provided by the patient 
 interface 46. 
 The power required to charge the battery 18 of the monitor-defibrillator 12
 is supplied by either an internal or an external power supply. As shown in
 FIG. 1, an internal power supply 38 may be used which is operatively 
 connected to the charger interface module 34. A switch mode type power 
 supply 38 is preferred. However, a linear type power supply 38 could also 
 be utilized. If a linear type power supply 38 is used, a heat sink and a 
 fan would be needed in the patient base station 30. Use of a switch mode 
 type power supply 38 would eliminate the fan, reduce the size of the heat 
 sinks and would reduce the size of the system package and is thus 
 preferred. 
 The power supply 38 utilizes a power entry module 36. The power entry 
 module 36 provides a standard IEC 320 type power entry connector. The 
 power entry module 36 functions over a full range of standard household 
 international voltages and frequencies. The power entry module 36 shall 
 preferably use a standard international "1/0" icon for power status 
 indication. 
 The monitor-defibrillator interface 32 is operatively connected to the 
 charger interface module 34 within the patient base station 30. The 
 charger interface module 34 provides a standard PC-AT compatible ISA type 
 interface and provides all the necessary bus signals for computer control 
 of the various charger interface module functions. In this way, data 
 received by the monitor-defibrillator interface 32 from the data 
 storage/processor 22 of the monitor-defibrillator 12 is provided to a 
 computer 40. In this way, communication is then established for transfer 
 of operational data to the patient base station mass data storage area 42.
 This data is a record of device performance and any ECG data that may have
 been stored within the monitor-defibrillator 12 during patient monitoring.
 Thus, the patient base station initiates data retrieval operations from the
 monitor-defibrillator 12 if operational or ECG data is stored within the 
 internal memory included in the data storage/processor 22 of the 
 monitor-defibrillator 12. As part of normal maintenance of the 
 monitor-defibrillator 12, this data is transferred to the patient base 
 station 30 for long-term data storage 42. The patient base station 30 may 
 store retrieved data on a removable floppy disk, removable or fixed hard 
 disk or other removable media. In the preferred embodiment, the data is 
 stored on a fixed hard disk. At the successful completion of data 
 transfer, the computer 40 of the patient base station 30 issues a clear 
 memory command via the monitor-defibrillator interface 32 to the 
 monitor-defibrillator 12. This command erases the temporary memory in the 
 data storage/processor 22 in the monitor-defibrillator 12. In the 
 embodiment utilizing rotating media, the patient base station notifies the
 patient when the removable media requires replacement due to inadequate 
 storage area remaining. 
 The computer 40 utilized by the patient base station 30 incorporates an 
 imbedded, PC-AT-compatible computer architecture. The computer 40 
 preferably utilizes an Intel.TM. 80.times.86 type central processing unit,
 with a performance no less than that of a 25 MHz 80386SX Intel.TM. 
 processor. The computer 40 preferably includes two standard PC-AT type 
 serial ports. A modem interface port 44 should also be available for 
 connecting the computer 40 to a telephone modem (not shown). The modem 
 interface 44 is designed to interface to a telephone modem with no less 
 than 14.4 kpbs data rate capability. The modem preferably interfaces to 
 the single board computer 40 via one of its serial ports. 
 A physician's programming console ("PPC") interface 48 provides a 
 communication link from the patient base station ("PBS") 30 to a 
 physician's programming console 70. The physician's programming console 
 interface 48 contains an ethernet communications module 52 for providing a
 standard 10 Mbps data link to the physician's programming console 70. This
 module 52 preferably interfaces to the single board computer 40 via an 
 expansion bus 54. Data transfers between the patient base station 30 and 
 the physician's programming console 70 are handled via the ethernet port 
 52. This allows the significant amount of data generated by the 
 monitor-defibrillator 12 to be offloaded in a reasonable time at the 
 physician's office during the patient's periodic visits. The external 
 panel connection for the high speed physician's programming console 70 
 data link can use a standard BNC type female connector. A serial 
 communications port 50 is also part of the physician programming console 
 interface 48 and is provided for connection of the computer 40 to the 
 physician's programming console 70. Data transfer from the patient base 
 station 30 to the physician's programming console 70 can also occur via 
 high speed modem interface 44 from the patient's home. 
 The computer 40 is operatively connected to an ISA type expansion bus 54. 
 The expansion bus 54 is designed to be capable of supporting up to four 16
 bit expansion modules or cards. The computer 40 utilizes the expansion bus
 54 to facilitate communications, control and status transfers to and from 
 the charger interface module 34 and ethernet communication module 52 of 
 the physicians programming console interface 48. The expansion bus 54 also
 provides power to the computer 40 and the ethernet communication module 52
 from the charger interface module 34. 
 The operating system and applications software for the patient base station
 30 may be stored on rotating media in the mass data storage area 42. 
 However, the preferred embodiment embeds this software in non-volatile 
 read only memory, such as EEPROM or FLASH memory. These embodiments allow 
 the device to operate without need of rotating media. Additional 
 non-volatile memory is provided to store certain manufacturing information
 and device-specific data. These memory locations are written to only 
 during the initial manufacturing processes and are then write inhibited by
 hardware means. As shown in FIG. 2, a real time clock may be implemented 
 in conjunction with the computer 40 to maintain date and time of day 
 information. The clock has backup power 62 provided to maintain operation 
 if power is removed from the patient base station. A counter-timer 72 is 
 provided to coordinate time critical operations. An analog to digital 
 converter 64 is also provided. 
 The patient base station computer 40 controls battery charging, both rapid 
 charging and float charging once the fill charge point is reached. The 
 computer 40 also controls discharging of the battery 18, as required. A 
 battery capacity test is periodically performed to verify the stored 
 energy capacity of the monitor-defibrillator battery pack 18. The system 
 processor 40 controls all battery capacity measurement operations by 
 discharging the battery 18 to a defined starting level, rapid-charging the
 battery 18 to full potential, implementing a timed discharge cycle to 
 deplete the battery 18 and calculating the actual energy capacity. This 
 process can determine if a bad cell is present in the battery pack, or the
 measured battery capacity is less than a defined acceptable limit. 
 The patient interface module 46, as shown in FIG. 5, can have a visual 
 display 47, battery status LED indicators 51, acknowledge push button 57 
 and ambient light sensor 49. The patient interface module 46 can be 
 operatively associated with the charger interface module 34 and the analog
 to digital converter 64. The analog to digital converter 64 with an analog
 multiplexer is preferably provided within the patient base station 30. 
 This analog to digital converter 64 allows the single board computer 40 
 (FIG. 1) to monitor the charging current of the charger/discharger 34, 
 discharging current of the charger/discharger 34, the battery voltage 
 present at the monitor-defibrillator interface 32, the ambient light 
 sensor 49 of the patient interface module 46 and the ambient temperature 
 within the patient base station 30 enclosure via a temperature sensor 55 
 (shown in FIG. 2). 
 Referring again to FIG. 1, the patient interface 46 in the patient base 
 station 30 indicates the status of the monitor-defibrillator battery 18 
 during the battery capacity test cycle. The patient interface 46 
 preferably incorporates a front panel mounted vacuum fluorescent (VF) type
 display 47 (shown in FIG. 4). This display 47 may be a character type with
 standard 5 mm, 5.times.7 dot characters. The PBS display 47 is preferably 
 arranged in one of the following configurations: a 2 line by 40 character 
 or a 4 line by 20 character. The PBS display 47 is controlled by the 
 single board computer 40 via the charger interface module 34 through a 
 parallel data interface. As an alternative, a graphics type LCD may be 
 used for the PBS display 47. If an LCD display is used, the patient base 
 station may include an ambient light sensor 49 to control the LCD 
 backlight for improved readability. 
 In addition, the patient base station 30 tracks battery 18 usage and 
 notifies the patient when replacement of the battery 18 is required. If 
 the battery 18 expiration parameters have been exceeded (the expiration 
 date or the number of charge cycles), the battery 18 can still be used by 
 the monitor-defibrillator 12, but the patient will be notified to replace 
 the monitor-defibrillator 12 as soon as possible. The number of charging 
 cycles performed on the battery 18 is recorded in the 
 monitor-defibrillator memory of the data storage/processor 22. Also, the 
 date the battery 18 was installed in the monitor-defibrillator 12, the 
 type of cell used in the battery 18, and the expiration date of the 
 battery 18 as well as any other pertinent information is stored in 
 monitor-defibrillator data storage/processor 22. 
 The communications interface created when the patient base station 30 and 
 attached monitor-defibrillator 12 is connected to the physician's 
 programming console 70 is utilized during the initial configuration 
 programming of the monitor-defibrillator 12. Preferably, the following 
 information is configured: name, address, telephone number, hospital, 
 attending physician, medications; monitor-defibrillator detection and 
 treatment parameters such as heart rate threshold or rate cutoff, 
 defibrillation energy to be delivered in therapy pulses; and 
 monitor-defibrillator manufacturing data such as device serial numbers, 
 monitor-defibrillator battery pack. and expiration date, electrode 
 harness(s) and expiration date(s). 
 A data communications protocol facilitates the transfer of digital 
 information between the patient base station 30 and the physician's 
 programming console 70. This protocol consists of transferring data in 
 blocks or frames. To ensure the integrity of transmitted and received 
 data, the protocol implements error checking techniques. 
 The patient base station 30 to physician's programming console 70 
 communications protocol consists of transferring data in frames. 
 Communication frames are transferred via the serial communication port 50.
 Serial communication port 50 hardware control lines are utilized to 
 provide handshaking between the patient base station 30 and the 
 physician's programming console 70 that will delimit the frame boundaries.
 Each communication cycle consists of a command frame sent from the 
 physician's programming console 70 to the patient base station 30, 
 followed by a response frame sent from the patient base station 30 to the 
 physician's programming console 70. Each command frame will contain a 
 command code followed by any relevant data, followed by an error checking 
 code such as a CRC code. 
 If the command is successfully processed by the patient base station 30, 
 the patient base station 30 will return a response frame that contains an 
 ACK code, followed by the original received command code, followed by any 
 relevant data, followed by an error checking code such as a CRC code. 
 If the command is not successfully processed by the patient base station 
 30, the patient base station 30 will return a response frame that contains
 a NAK code, followed by the original received command code, followed by 
 any relevant data, followed by an error checking code such as a CRC code. 
 If a command frame is received by the patient base station 30 that contains
 an invalid error checking code, the patient base station 30 will ignore 
 the communication frame. The physician's programming console 70 will be 
 responsible for monitoring the patient base station 30 response. If the 
 patient base station 30 does not respond to a command frame the 
 physician's programming console 70 can elect to resend the frame. 
 If a response frame is received by the physician's programming console 70 
 that contains an invalid error checking code, the physician's programming 
 console 70 can elect to resend the frame. 
 Another data communications protocol facilitates the transfer of digital 
 information between the monitor-defibrillator 12 and the patient base 
 station 30. The protocol consists of transferring data in blocks or 
 frames. 
 The patient base station ("PBS") 30 to monitor- defibrillator ("M-D") 12 
 communications protocol consists of transferring data in frames. 
 Communication frames are transferred via the PBS/M-D interface 32. PBS/M-D
 interface 32 hardware control lines are utilized to provide handshaking 
 between the patient base station 30 and the monitor-defibrillator 12 that 
 will delimit communication frame boundaries. Each communication cycle 
 consists of a command frame sent from the patient base station 30 to the 
 monitor-defibrillator 12, followed by a response frame sent from the 
 monitor-defibrillator 12 to the patient base station 30. Each command 
 frame will contain a command code followed by any relevant data, followed 
 by an error checking code such as a CRC code. 
 If the command is successfully processed by the monitor-defibrillator 12, 
 the monitor-defibrillator 12 will return a response frame that contains an
 ACK code, followed by the original received command code, followed by any 
 relevant data, followed by an error checking code such as a CRC code. 
 If the command is not successfully processed by the monitor-defibrillator 
 12, the monitor-defibrillator 12 will return a response frame that 
 contains a NAK code, followed by the original received command code, 
 followed by any relevant data, followed by an error checking code such as 
 a CRC code. The patient base station 30 will determine and execute a 
 response appropriate for the failed monitor-defibrillator 12 command 
 process. 
 If a command frame is received by the monitor-defibrillator 12 that 
 contains an invalid error checking code, the monitor-defibrillator 12 will
 return a response frame that contains a code indicating that the command 
 was not properly received and should be resent. The patient base station 
 30 can elect to resend the command frame. 
 If a response frame is received by the patient base station 30 that 
 contains an invalid error checking code, the patient base station 30 can 
 elect to resend the frame or initiate monitor-defibrillator 12 fault 
 condition processing. 
 The patient base station 30 offers a collection of commands that the 
 physician's programming console 70 can utilize during communications with 
 the patient base station 30. The command set provides a means to initiate 
 various patient base station 30 and monitor-defibrillator 12 diagnostic, 
 configuration, and data retrieval procedures. 
 The physician's programming console 70 can gain access to various 
 monitor-defibrillator 12 information and operational features by issuing 
 commands to the patient base station 30 via the serial communications port
 50. Upon receipt of these commands, the patient base station 30 will issue
 the appropriate commands to the monitor-defibrillator 12 via the PBS/ M-D 
 interface 32, that will carry out the desired operation. The patient base 
 station 30 will return to the physician's programming console 70 the 
 monitor-defibrillator 12 response to the operation. 
 A digital output from the monitor-defibrillator data storage/processor is 
 provided to control the activation of the battery test load. Activation of
 the load places a high current demand on the monitor-defibrillator battery
 18. This determines if the monitor-defibrillator battery pack contains any
 defective cells. The monitor-defibrillator 12 can determine the available 
 device operation time (prior to recharging the battery) utilizing 
 adjustments for abnormally high current draw, normal current draw, device 
 fault conditions, and depletion of battery capacity during periods when 
 the device is not in use. 
 Upon command from the patient base station or the monitor-defibrillator 
 display, the monitor-defibrillator 12 performs a battery load test. The 
 monitor-defibrillator 12 returns a pass-fail indication to the patient 
 base station or the display. Load tests are most often performed with the 
 display as the host. If the battery 18 fails the load test, the battery 
 voltage measurement prior to the load test and at the point of failure are
 stored in the monitor-defibrillator non-volatile memory. 
 Referring to FIG. 3, the patient base station 30 provides circuitry in the 
 charger interface module 34, that can charge or discharge the 
 monitor-defibrillator 12 battery pack 18. The charger interface module 34 
 connects to the monitor-defibrillator 12 battery pack 18 via the PBS/M-D 
 interface 32. Prior to battery pack 18 maintenance operations, the patient
 base station 30 will retrieve battery pack 18 identification information 
 from the monitor-defibrillator 12 via the PBS/M-D interface 32. 
 Two charging modes are provided; rapid charging and float charging. During 
 the rapid charge cycle the charger interface module 34 supplies charging 
 current at the one hour charge rate of the battery pack 18. During float 
 charge operations, the charger interface module 34 supplies charging 
 current at the continuous maintenance rate of the battery pack 18. 
 The rapid and float charge current rates supplied by the charger interface 
 module 34 are adjustable by the patient base station computer 40. The 
 patient base station computer 40 will configure the charger interface 
 module 34 to supply a charge current rate that is appropriate for the 
 connected battery pack 18. 
 During the discharge cycle, the charger interface module 34 provides a 
 resistive load to the battery pack 18 that discharges the battery pack 18 
 at the one hour discharge rate of the battery pack 18. The discharge 
 resistive load applied by the charger interface module 34 is adjustable by
 the patient base station computer 40. The patient base station computer 40
 will configure the charger interface module 34 to apply a resistive load 
 that causes a one hour current drain rate that is appropriate for the 
 connected battery pack 18. 
 The battery charger interface module 34 can be controlled by the patient 
 base station computer 40 or by the monitor-defibrillator 12 via the 
 PBS/M-D interface 32. Monitor-defibrillator 12 control of the charger 
 interface module 34 is accomplished by activating I/O control lines 
 located in the PBS/M-D interface 32. These I/O lines will configure the 
 charger interface module 34 for the desired charge/discharge operation. 
 Alternately, the patient base station computer 40 can control the I/O 
 lines and configure the charger interface module 34 for the desired 
 charge/discharge operation. Under normal operation the 
 monitor-defibrillator 12 controls the configuration of the charger 
 interface module 34. The patient base station 30 configuration of the 
 charger interface module 34 is a redundant feature that can be utilized if
 certain monitor-defibrillator 12 fault conditions exist such as a totally 
 discharged monitor-defibrillator 12 battery pack 18. 
 Battery pack 18 charge and discharge cycles are initiated by the patient 
 base station computer 40. When a monitor-defibrillator 12 is connected to 
 the patient base station 30, the patient base station 30 retrieves 
 monitor-defibrillator 12 battery operational status data from the data 
 storage/processor 22 via PBS/M-D interface 32. The retrieved battery 
 operational status data includes information such as the remaining battery
 capacity, fault condition flags, expiration parameters, battery 
 maintenance parameters, and battery identification information. The 
 patient base station 30 analyzes the retrieved battery data to determine 
 the appropriate battery pack 18 maintenance procedure. 
 If the patient base station 30 determines that a rapid charge cycle is 
 required, a command to initiate a rapid charge cycle will be sent to the 
 monitor-defibrillator 12 via the PBS/M-D interface 32. Upon receipt of 
 this command, the monitor-defibrillator 12 will configure the charger 
 interface module 34 for rapid charge operation by activating I/O control 
 lines located in the PBS/M-D interface 32. The monitor-defibrillator 12 
 will monitor the rapid charge sequence for completion and fault 
 conditions. Successful rapid charge completion is determined by the 
 monitor-defibrillator 12 monitoring the voltage level at the battery pack 
 18 positive terminal via the A/D converter located in the data 
 storage/processor module 22. Successful rapid charge completion can also 
 be declared if the monitor-defibrillator 12 detects a defined change in 
 battery pack 18 temperature. The monitor-defibrillator 12 monitors the 
 battery temperature via a temperature sensor located in the battery pack 
 18 and the A/D converter located in the data storage/processor module 22. 
 When the monitor-defibrillator 12 detects a successful rapid charge 
 completion, the monitor-defibrillator 12 will configure the charger 
 interface module 34 for float charge operation by activating I/O control 
 lines located in the PBS/M-D interface 32, reset the monitor-defibrillator
 12 runtime parameter to the maximum value, and issue a rapid charge 
 complete communications frame to the patient base station 30 via the 
 PBS/M-D interface 32. 
 The rapid charge cycle will be aborted if the monitor-defibrillator 12 
 detects one of the following conditions: a battery pack 18 over voltage 
 condition; a battery pack 18 over temperature condition; or a defined time
 interval elapsed without a rapid charge completion detected. The limit 
 values are manufacturing parameters that are stored in the 
 monitor-defibrillator 12 data storage/processor module 22. 
 If the monitor-defibrillator 18 aborts the rapid charge cycle the following
 operations will be performed: the monitor-defibrillator 12 will configure 
 the charger interface module 34 for float charge operation by activating 
 I/O control lines located in the PBS/M-D interface 32; the 
 monitor-defibrillator 12 will set it's runtime parameter to zero, which 
 will cause patient warning messages on the display 24; and the 
 monitor-defibrillator 12 will issue a rapid charge fault communications 
 frame to the patient base station 30 via the PBS/M-D interface 32. If the 
 patient base station 30 receives a rapid charge fault communications frame
 from the monitor-defibrillator 12, the following operations will be 
 performed: the event will be logged in the patient base station 30 
 operations log file located in the data storage module 42; and the patient
 base station 30 will activate a patient warning message that indicates the
 monitor-defibrillator 12 should be serviced. 
 During the rapid charge cycle, the patient base station 30 will insure 
 proper charge operation by monitoring various system parameters. The 
 system parameter limit values are stored in the data storage module 42 
 during the patient base station 30 manufacturing process. 
 The charging current supplied to the battery pack 18 is monitored for 
 proper levels via an A/D converter 64 (FIG. 5) channel connected to the 
 charger interface module 34. If the measured current is outside the 
 defined limits, the patient base station 30 will abort the rapid charge 
 cycle. 
 The charging voltage on the battery pack 18 is monitored for proper levels 
 via an A/D converter 64 channel connected to the charger interface module 
 34. If the measured voltage is outside the defined limits, the patient 
 base station 30 will abort the rapid charge cycle. 
 The patient base station 30 will abort the rapid charge cycle if the 
 counter timer 72 (FIG. 2) indicates the charge cycle exceeded the maximum 
 charge completion interval. 
 If the patient base station 30 determines that a rapid charge cycle abort 
 is required, the following operations will be performed: an abort rapid 
 charge cycle command will be issued to the monitor-defibrillator 12 via 
 the PBS/M-D interface 32; the patient base station 30 will configure the 
 charger interface module 34 for float charge operation; the patient base 
 station 30 will issue a command to the monitor-defibrillator 12 to set the
 runtime parameter to zero, which will cause patient warning messages on 
 the display 24; the event will be logged in the patient base station 30 
 operations log file located in the data storage module 42; and the patient
 base station 30 will activate a patient warning message that indicates the
 monitor-defibrillator 12 should be serviced. 
 The patient base station 30 may initiate a discharge cycle of the 
 monitor-defibrillator 12 battery pack 18. The discharge cycle is utilized 
 both during the battery capacity test as well as during the process of 
 reconditioning the battery energy storage capabilities. 
 If the patient base station 30 determines that a discharge cycle is 
 required, a command to initiate a discharge cycle will be sent to the 
 monitor-defibrillator 12 via the PBS/M-D interface 32. Upon receipt of 
 this command the monitor-defibrillator 12 will set the 
 monitor-defibrillator 12 runtime parameter to zero and configure the 
 charger interface module 34 for discharge operation by activating I/O 
 control lines located in the PBS/M-D interface 32. The 
 monitor-defibrillator 12 will monitor the discharge sequence for 
 completion and fault conditions. Successful discharge completion is 
 determined by the monitor-defibrillator 12 detecting the defined final 
 discharge voltage threshold on the battery pack 18 positive terminal via 
 the A/D converter located in the data storage/processor module 22. When 
 the monitor-defibrillator 12 detects a successful discharge completion, 
 the monitor-defibrillator 12 will configure the charger interface module 
 34 for float charge operation, by activating I/O control lines located in 
 the PBS/M-D interface 32, and issue a discharge complete communications 
 frame to the patient base station 30 via the PBS/M-D interface 32. 
 The discharge cycle will be aborted if the monitor-defibrillator 12 detects
 one of the following conditions: a battery pack 18 over temperature 
 condition; or a defined time interval has elapsed without the detection of
 the discharge complete condition. The limit values are manufacturing 
 parameters that are stored in the monitor-defibrillator 12 data 
 storage/processor module 22. 
 If the monitor-defibrillator 12 aborts the discharge cycle the following 
 operations will be performed: the monitor-defibrillator 12 will configure 
 the charger interface module 34 for float charge operation by activating 
 I/O control lines located in the PBS/M-D interface 32; and the 
 monitor-defibrillator 12 will issue a discharge fault communications frame
 to the patient base station 30 via the PBS/M-D interface 32. If the 
 patient base station 30 receives a discharge fault communications frame 
 from the monitor-defibrillator 12, the event will be logged in the patient
 base station 30 operations log file located in the data storage module 42 
 and a patient warning message will be activated on the PBS display 47 that
 indicates the monitor-defibrillator 12 should be serviced. 
 During the discharge cycle, the patient base station 30 will insure proper 
 discharge operation by monitoring various system parameters. The system 
 parameter values are stored in the data storage module 42 during the 
 patient base station 30 manufacturing process. 
 The discharge current drawn from the battery pack 18 is monitored for 
 proper levels via an A/D converter 64 channel connected to the charger 
 interface module 34. If the measured current is outside the defined 
 limits, the patient base station 30 will abort the discharge cycle. 
 The discharge voltage on the battery pack 18 is monitored for proper levels
 via an A/D converter 64 channel connected to the charger interface module 
 34. If the measured voltage is outside the defined limits, the patient 
 base station 30 will abort the discharge cycle. 
 The patient base station 30 will abort the discharge cycle if the counter 
 timer 72 indicates the discharge cycle exceeded the maximum discharge 
 completion interval. 
 If the patient base station 30 determines that a discharge cycle must be 
 terminated, the following operations will be performed: an abort discharge
 cycle command will be issued to the monitor-defibrillator 12 via the 
 PBS/M-D interface 32; the patient base station 30 will configure the 
 charger interface module 34 for float charge operation; the patient base 
 station 30 will issue a command to the monitor-defibrillator 12 to set the
 runtime parameter to zero, which will cause patient warning messages on 
 the display 24; the event will be logged in the patient base station 30 
 operations log file located in the data storage module 42; and the patient
 base station 30 will activate a patient warning message that indicates the
 monitor-defibrillator 12 should be serviced. 
 The rapid charge cycle or discharge cycle will not be initiated if the 
 monitor-defibrillator 12 determines that the battery pack 18 temperature 
 is outside a set of defined limits. The limit values are manufacturing 
 parameters that are stored i n the monitor-defibrillator 12 data 
 storage/processor module 22. 
 If the monitor-defibrillator 12 is removed from the patient base station 30
 prior to completion of all battery pack maintenance operations, a message 
 and alarm will be activated on the patient interface module 46. The 
 message will indicate the monitor-defibrillator maintenance is not 
 complete and to return the monitor-defibrillator to the patient base 
 station. The interrupted maintenance procedure will be continued if the 
 removed monitor-defibrillator 12 is reconnected to the patient base 
 station 30. 
 The energy delivery capabilities of the battery pack 18 are periodically 
 verified by testing the battery 18 energy capacity and high current 
 delivery capabilities. The patient base station 30 will perform an energy 
 capacity test on the battery pack 18 if the elapsed time from the last 
 capacity test, as indicated by data retrieved from monitor-defibrillator 
 data storage/processor module 22 via the PBS/M-D interface 32, exceeds the
 maximum time interval parameter stored in the data storage module 42, or 
 status data retrieved from monitor-defibrillator data storage/processor 
 module 22 via the PBS/M-D interface 32, indicates that the battery 18 
 operational performance was deficient during the previous patient 
 monitoring cycle. 
 The battery 18 energy capacity test procedure consists of the following 
 operations: the patient base station 30 will activate a message on the 
 patient interface 46 visual display 47 that indicates the 
 monitor-defibrillator 12 is being tested and to wait for the test to 
 complete; the patient base station 30 initiates a battery discharge cycle 
 to condition the battery for a full charge cycle; initiate a rapid charge 
 cycle when the discharge cycle is complete to charge the battery 18 to 
 full capacity; the patient base station 30 initiates a second discharge 
 cycle when the rapid charge cycle is complete; and the patient base 
 station 30 initiates a final rapid charge cycle at the completion of the 
 second discharge cycle to ready the battery 18 for service. The duration 
 of the second discharge cycle is timed by a counter timer located in the 
 monitor-defibrillator 12 data storage/processor module 22. At the 
 completion of the second discharge cycle the monitor-defibrillator 12 will
 compare the measured battery 18 discharge time with an acceptance 
 parameter stored in storage/processor module 22. If the capacity discharge
 time is within the acceptable limit, monitor-defibrillator 12 will issue a
 capacity discharge pass communications frame to the patient base station 
 30 via the PBS/M-D interface 32. 
 If the capacity discharge time is not within the acceptable limit, the 
 monitor-defibrillator 12 will set a battery capacity fault status flag 
 located in the data storage/processor module 22, and issue a capacity 
 discharge fault communications frame to the patient base station 30 via 
 the PBS/M-D interface 32. The patient base station 30 will log the event 
 in a log file located in the data storage module 42. Whenever the patient 
 base station 30 receives a capacity discharge fault indication from the 
 monitor-defibrillator 12, a patient warning message will be activated 
 which indicates that the monitor-defibrillator 12 should be serviced as 
 soon as possible. Each time a monitor-defibrillator 12 is connected to the
 patient base station 30, the patient base station 30 will retrieve the 
 monitor-defibrillator 12 battery capacity fault status flag located in the
 data storage/processor module 22. If the battery capacity fault status 
 flag is active, the patient base station 30 will initiate normal battery 
 maintenance operations, with the exception of the battery capacity test 
 which will no longer be performed. The patient base station 30 will also 
 issue a command to the monitor-defibrillator 12 to set the runtime 
 parameter to zero. This will cause repeated patient warning messages on 
 the patient display 24. 
 If the battery status information indicates that the expiration date of the
 battery 18 has been exceeded (status information is entered during the 
 initial configuration programming) or if the maximum number of charge 
 cycles has been exceeded, the patient will be notified by the patient base
 station 30 that the monitor-defibrillator 12 should be serviced. The 
 notification sequence will be activated until the patient acknowledges 
 receipt by pressing a button 57 (FIG. 4) on the patient interface 46, or 
 the monitor-defibrillator 12 is removed from the patient base station 30. 
 Normal battery maintenance will continue so that the patient may use the 
 monitor-defibrillator 12. 
 When a rapid charge cycle or battery discharge cycle is initiated, the 
 patient base station 30 will deactivate the particular one of the battery 
 status LED indicators 51 which is the "READY" LED indicator on the patient
 interface module 46 and activate the particular one of the battery status 
 LED indicators 51 which is the "CHARGING" LED indicator. During the rapid 
 charge cycle, the patient base station 30 displays a message on the 
 patient interface visual display 47 that the monitor-defibrillator battery
 18 is being charged and the monitor-defibrillator 12 is not ready for use.
 If monitor-defibrillator maintenance operations are complete at the 
 conclusion of a successful rapid charge cycle, the patient base station 
 performs the following: 
 A message is displayed on the PBS display 47 indicating that the 
 monitor-defibrillator 12 is ready for use; the PBS 30 "READY" LED 51 is 
 activated; the "CHARGING" LED 51 is deactivated; and the 
 monitor-defibrillator 12 is powered down. 
 The patient base station 30 logs the following battery maintenance 
 information into a maintenance log: the start and completion times of 
 battery operations; the length of the charge/discharge cycles; any 
 abnormal conditions; and the charge cycle count, and if enabled, the 
 battery voltage measurements taken during charge and discharge cycles. The
 maintenance log is stored in the data storage module 42. 
 The patient base station 30 issues various diagnostic test commands to the 
 monitor-defibrillator 12. These tests are performed on a regular basis. 
 Some tests are performed each time the monitor-defibrillator 12 is 
 connected to the patient base station 30. Others are performed only as 
 required. The monitor-defibrillator 12 executes the received commands and 
 reports the test results to the patient base station 30. The patient base 
 station 30 maintains a log of the test results on the mass storage media 
 42. If a fault is detected during any diagnostic procedure, the patient is
 notified of the condition along with the appropriate corrective action. 
 Other variations are also possible. For example, the preferred patient base
 station 30 utilizes a charger interface module board. Stacked on top of 
 that board are purchased assemblies of PC104 boards which form the CPU 
 module 40 and Ethernet module 52. These boards are ISA compatible because 
 the expansion bus 54 is an ISA type bus. The stacks of PC104 boards 
 require a great deal of cabling which is very costly. Thus, all of the 
 major system functions could be implemented on a single PC board. This 
 would eliminate much of the cabling. 
 Moreover, alternative embodiments of the battery management system are 
 contemplated. Particularly, referring to FIG. 6, a basic perspective view 
 of an alternative embodiment of a battery management system 110 is shown 
 having a monitor defibrillator 112, rechargeable battery pack 118 and 
 battery pack recharger 190. A battery pack receptacle 182 is provided in 
 the monitor-defibrillator 112 wherein the battery pack 118 is adapted to 
 be received for use as a power supply. Also, the recharger 190 includes a 
 battery pack receptacle 184 to receive the battery pack 118 for recharging
 and, if desired, testing to determine the operational condition of the 
 battery pack 118. The battery pack 118 memory/processor is configured to 
 exchange information with both a processor in the recharger 190 and the 
 data storage/processor 22 in the monitor-defibrillator 112. 
 As can be seen in the simplified diagram shown in FIG. 7, all of the 
 heretofore described functions carried out by the patient base station 30,
 except for the battery recharging and related functions, can be carried 
 out by an upgraded monitor-defibrillator 112 having increased functional 
 capabilities. Basically, the monitor-defibrillator 112 package has been 
 upgraded/expanded to include the circuitry necessary to perform the 
 functions of not only the previously described monitor-defibrillator 12, 
 but additionally, the functions formerly performed by the patient base 
 station 30. Of course, some of the components in the previous embodiments 
 of the monitor-defibrillator 12 and patient base station 30, are 
 eliminated, for example the respective interface modules 26 and 32, 
 external power supply 60, power entry module 36, power supply 38, computer
 40 and battery charger interface module 34 that are not required for the 
 expanded function monitor-defibrillator 112. Some of the components are 
 obsoleted by the fact that the monitor-defibrillator 112 no longer 
 interfaces with a base station. Other components, such as those related to
 battery recharging will be part of the battery charger 190 to be used with
 the smart battery pack 118. Thus, the monitor-defibrillator 112 can 
 include maintenance circuitry for providing an indication of the operation
 condition of the monitor-defibrillator 112 whereas the battery recharger 
 190 can include battery maintenance circuitry for providing an indication 
 of the operating condition of the rechargeable battery pack 118. 
 Other elements of the prior embodiment of the battery management system 10,
 such as the computer 40, are redundant with components in the 
 monitor-defibrillator 112. For example, the data storage/processor 22 is 
 also a "computer." However, the functioning of the data storage/processor 
 22 may also be upgraded with regard to memory and processing capabilities 
 in order to handle the added functionality taken over by the 
 monitor-defibrillator 112. Additionally, another input/output 170 option 
 is an infrared communication module 53, which can be used in addition to 
 the serial port 50 or ethernet module 52. 
 The battery management system 110 also contemplates the use of what is 
 known as a "smart battery" pack 118. A smart battery is a relatively new 
 type of battery which has an internal memory/processor that monitors the 
 condition of the battery and can also communicate with a battery recharger
 190 designed to recharge such smart battery packs. The pack recharger 190 
 also has a processor to read and update the memory/processor in the smart 
 battery pack 118. Moreover, the recharger 190 can include the battery pack
 recharging, maintenance and testing functionality previously performed by 
 the patient base station 30. Additionally, the smart battery pack 118 
 memory/processor can communicate with data storage/processor 22 in the 
 monitor-defibrillator 112. A preferred smart battery pack 118 and 
 recharger 190 are described in more detail below, in connection with FIGS.
 8 and 9. 
 As explained above, the monitor-defibrillator 112 performs, in addition to 
 the functions previously described for the monitor-defibrillator 12, all 
 the functions previously associated with the patient base station 30, 
 except battery recharging. The monitor-defibrillator 112 has a receptacle 
 182 adapted to receive the smart battery pack 118 for use as a power 
 supply, communicates therewith to ascertain the battery condition stored 
 in the memory of the smart battery 118, performs test operations thereon, 
 and can update the internal memory regarding the battery condition when 
 appropriate. Both the battery pack 118 and the battery pack receptacle 182
 in the monitor-defibrillator 112 are provided with the requisite contacts 
 and interfaces necessary for the monitor-defibrillator to be powered by 
 the battery pack 118 and also for the data storage/processor 22 in the 
 monitor-defibrillator 112 to exchange information with the 
 memory/processor in the smart battery pack 118. 
 As will be described below in more detail, the smart battery pack 118 is 
 equipped to monitor the battery drain only for the computer circuitry of 
 the monitor-defibrillator 112, it is not designed to monitor the current 
 drain caused by the high voltage converter. Thus, the upgraded 
 monitor-defibrillator 112 can independently monitor the charge status of 
 the battery. This separate energy monitoring function can be, for example,
 provided by an "energy monitoring circuit" 180 which very precisely 
 measures the energy output of the converter-defibrillator circuit 19, 
 which energy is, of course, provided by the smart battery pack 118. The 
 monitor-defibrillator 112 can then update the memory of the smart battery 
 pack 118 with this information to determine the final condition of the 
 battery regarding the available energy. 
 The smart battery and recharger hardware will supply various diagnostic 
 capabilities to the battery management system. The capabilities will 
 include providing accurate run-time information to the 
 monitor-defibrillator 112, storage of fault flag information for both the 
 monitor-defibrillator 112, and storage of information which allows both 
 the battery charger and monitor-defibrillator 112 to adapt operation to 
 different types of smart batteries. 
 Described below are certain software interface and data structures which 
 can preferably be used in the smart battery interface. FIGS. 8 and 9 
 illustrate certain preferred flow diagrams which can be used as a guide 
 during the design and implementation of both the battery charger 190 and 
 monitor-defibrillator 112 software. 
 Determination and Adjustment of Monitor-Defibrillator Available Run Time 
 The determination of available monitor-defibrillator 112 run time is based 
 upon multiple factors. The design of the monitor-defibrillator smart 
 battery pack 118 preferably includes a BenchMarq.TM. Model BQ2092 "gas 
 gauge" integrated circuit. The BQ2092 continuously monitors the current 
 being consumed by the monitor-defibrillator 112 and adjusts an internal 
 capacity register. The monitor-defibrillator 112 reads the capacity 
 register to determine available operating time which is displayed to the 
 patient in hours and minutes. The smart battery pack 118 internal 
 circuitry has been designed to particularly monitor the current being 
 drawn by the data storage/processor circuitry of the monitor-defibrillator
 112. However, the current drain caused by operation of the high voltage 
 converter (approximately 8 amps) is not monitored by the BenchMarq gas 
 gauge. Even if it were, the conventional internal circuitry could not 
 measure the current drain with the desired precision. Due to this, the 
 monitor-defibrillator 112 can have, for example, the aforementioned energy
 monitoring circuit 180 for precisely measuring this current drain and 
 using this information to make an appropriate adjustment to the smart 
 battery pack 118 gas gauge, based on measuring the operation time of the 
 converter. The remaining capacity register of the smart battery pack 118 
 will be adjusted based on a calculation performed by the 
 monitor-defibrillator 112 after operation of the converter. 
 Additionally, due to the design of the monitor-defibrillator 112, the 
 remaining capacity register contained in the BenchMarq BQ2092 IC does not 
 provide enough information to accurately determine the remaining run time 
 of the monitor-defibrillator 112. The monitor defibrillator 112 design 
 specifications indicate that the monitor-defibrillator 112 must be able to
 operate for a period of 24 hours, and at the end of the 24 hour period, be
 able to deliver five full energy defibrillation pulses without entering 
 converter foldback mode. Converter foldback mode is a mode of converter 
 operation that is enabled if the battery pack terminal voltage falls below
 a predefined threshold during operation of the converter interface. As a 
 result of this specification, the smart battery pack 118 must have 
 sufficient reserve capacity to operate the converter interface while 
 maintaining a battery pack voltage which is above this threshold. Due to 
 the five pulse requirement, the smart battery pack 118 must have 
 additional calibration information stored in the battery pack memory which
 allows the monitor-defibrillator 112 to verify that sufficient reserve 
 capacity exists in the battery to operate the converter at the 24 hour 
 operating point. 
 A reserve battery capacity calibration constant, "ReserveCapacityCutoff," 
 will be stored in each monitor-defibrillator 112 during manufacturing. The
 value of ReserveCapacityCutoff must be determined by a battery 
 qualification test which exercises the smart battery pack 118 under 
 simulated current drawings. The monitor-defibrillator 112 software will 
 read this constant during initialization and use it to determine run time 
 based on the following formula: 
EQU (RemainingCapacity-ReserveCapacityCutoff).div.SystemCurrent=CurrentRuntime.
 In the above formula, the constants ReserveCapacityCutoff and SystemCurrent
 must be maintained in the monitor-defibrillator 112 data storage/processor
 22. The battery pack 118 will also maintain a RemainingCapacity (command 
 code 0x0F) register which will be used to determine available operating 
 time and which is adjusted by circuitry internal to the battery pack 118 
 based on actual sensed battery current drain. The monitor-defibrillator 
 112 software generally decrements its run time counter in a linear 
 fashion. In one method, adjustments to the run time, outside of a straight
 decrement in time, will only be made if the above calculation indicates a 
 run time less than the decremented time amount or operation of the high 
 voltage converter occurs time amount or operation of the high voltage 
 converter occurs. However, in a presently preferred method, the 
 monitor-defibrillator 112 predicts the amount of operating time remaining 
 based on actual usage. The current drain of the system is measured by 
 hardware/software in the monitor-defibrillator 112, this is in addition to
 the smart battery pack 118, and averaged over a defined interval. When the
 run time value is needed, e.g. the patient pressing the display button or 
 a periodic system low battery check, the monitor-defibrillator 112 will 
 calculate the estimated run time amount based on the RemainingCapacity 
 value that is maintained in the smart battery pack 118 and the average 
 current consumption measured by the RemainingCapacity (0x0F) register. 
 This run time value is a more realistic prediction of how long the system 
 will operate based on actual usage. The only time the smart battery pack 
 118 RemainingCapacity register value is adjusted by the 
 monitor-defibrillator 112, is during converter operation. If an adjustment
 becomes necessary, the monitor-defibrillator 112 will modify the battery 
 pack 118 RemainingCapacity (0x0F) register with a new capacity value based
 on the duration of converter operation. 
 When a battery pack 118 is initially inserted into the 
 monitor-defibrillator 112, the above formula will be used to initialize 
 the initial run time variable CurrentRuntime. The Current/Runtime variable
 is decremented based on elapsed time after the initial calculation is 
 performed. 
 Periodically, the monitor-defibrillator 112 will recalculate the formula 
 and compare the calculated run time to the run time which is being 
 decremented based upon elapsed time. If the new calculated run time 
 indicates less time available than the CurrentRuntime variable, the 
 variable will be set equal to the calculated time. This situation may 
 occur if the patient display is activated for significant periods of time,
 causing greater than average current drain from the battery. 
 Monitor Defibrillator Battery Initialization Sequence 
 The flow diagram shown in FIG. 8 illustrates one presently preferred 
 embodiment of software flow during initialization of the 
 monitor-defibrillator 112 when a battery pack 118 is installed. The 
 initial calculation of CurrentRuntime is performed along with a test for 
 charger detected error conditions. A status variable, 
 "BatteryErrorStatus," maintained in the battery pack is shared by the 
 monitor-defibrillator 112 and charger. Variable BatteryErrorStatus, 
 located in the battery pack 118 ManufacturerAccess (Command code 0x00) 
 register low byte, is used by the monitor-defibrillator 112 to flag the 
 battery charger 190 to perform a capacity test cycle after certain 
 operating conditions are detected such as converter foldback or a low 
 battery voltage state. Detected error conditions and resulting battery 
 charger 190 operations are described later in this document. 
 Battery Capacity Testing and General Charger Functionality 
 In addition to basic battery charging sequences, the battery charger 190 
 can conduct periodic battery capacity measurements and monitor the 
 integrity of the battery pack 118. The battery pack 118 capacity test will
 be initiated based on checking an internal battery pack register value, 
 "TestCycleNumber," that will be stored in the ManufacturerAccess (Command 
 code 0x00) register high byte of the BQ2092. Variable TestCycleNumber is 
 reset to zero by the charger 190 whenever a battery capacity test cycle 
 has been completed. This value is maintained and updated by the charger 
 190 whenever the battery pack 118 completes a charge cycle. Manufacturing 
 constant "CyclesPerTestSequence" will be stored in the manufacturing data 
 (command code 0x23) area of the BenchMarq BQ2092 IC. Constant 
 CyclesPerTestSequence will be programmed at the time of manufacturing and 
 will indicate the number of charge cycles between capacity test sequences.
 When a smart battery pack 118 is inserted into the charger 190, the charger
 190 will read variables TestCycleNumber and CyclesPerTestSequence and 
 determine if a capacity test cycle is required. Prior to commencement of 
 the capacity test it will be necessary for the charger 190 to determine if
 the patient's current battery pack 118 is capable of sustaining 
 monitor-defibrillator 112 operations for the duration of the test. The 
 battery charger 190 will not initiate a battery capacity test sequence if 
 the previously charged battery pack 118 has Bit 1 of the 
 BatteryErrorStatus set or does not have sufficient reserve capacity to 
 operate the monitor-defibrillator 112 for the duration of the test. 
 As mentioned in the previous section, it is also possible that the 
 monitor-defibrillator 112 may periodically request a battery capacity test
 via variable BatteryErrorStatus Bit 0 contained in the BenchMarq BQ2092 
 ManufacturerAccess (Command code 0x00) register low byte. The following 
 details the bit positions in BatteryErrorStatus and their meaning. 
 BatteryErrorStatus (Low Byte of ManufacturerAccess (0x00) 
 Bit 0: Set by the monitor-defibrillator 112 if converter foldback or low 
 battery voltage condition exists during operation. 
 Bit 1: Set by battery charger if the smart battery pack 118 fails battery 
 capacity test or the battery pack 118 is otherwise defective. 
 If the battery charger 190 detects that Bit 0 of BatteryErrorStatus is set,
 the charger 190 should proceed to perform a battery capacity test. The 
 charger 190 must keep track of the time when a fully charged battery pack 
 118 was removed from the charger 190 and assume that it will power the 
 monitor-defibrillator 112 system for a period of twelve hours. The 
 decision to perform the battery capacity test must take into consideration
 the actual worst case duration of the test and the remaining run time of 
 the last fully charged battery pack 118. The test should not be initiated 
 if the battery pack 118 which is currently being used by the patient does 
 not have sufficient reserve capacity to power the monitor-defibrillator 
 112 for the worse case capacity test time or if the battery pack 118 is 
 faulty (Bit 1 is set). 
 Upon completion of the capacity test, the charger 190 should compare the 
 measured battery capacity to battery pack 118 parameter LowLimitCapacity 
 which is stored in the manufacturing data area. If the battery pack 118 
 capacity is less than this value, the charger 190 should clear Bit 0 & set
 Bit 1 of variable BatteryErrorStatus. If the test passes, then both error 
 Bits should be cleared. 
 The flow diagram shown in FIG. 9 illustrates one general, presently 
 preferred, method of operation of the battery charger 190. When a smart 
 battery pack 118 is removed from the system or not installed, all status 
 illuminators should be turned off. 
 Mapping of Defined Variables to BQ2092 Memory 
 The previously defined battery maintenance constants will be mapped into 
 the manufacturing data area and the variables mapped to the registers of 
 the BQ2092. This section defines the storage locations of the variables 
 and constants in the BQ2092. The variables and constants must be 
 initialized to default values during the battery pack manufacturing 
 process. 
 
 Constant Name Size in Bytes Manufacturing String Index 
 Low Limit Capacity 2 BASE ADDRESS+0&1 
 CyclesPerTestSequence 
 Variable Name Size in Bytes Register Location in BenchMarq BQ2092 
 BatteryErrorStatus 1 ManufacturerAccess(0x00) Low Byte 
 TestCycleNumber 1 ManufacturerAccess(0x00) High Byte 
 Regarding the manufacturing string address, the base address indicates the 
 first byte of the manufacturing data string provided by BQ2092 function 
 ManufacturingData (command code 0x23). 
 In accordance with the patent statutes we have described principles of 
 operation and preferred embodiments of our invention. It should be 
 understood, however, that within the scope of the appended claims, the 
 invention may be practiced in a manner other than as illustrated and 
 described.