SYSTEM AND METHOD FOR EXTENDING THE STORAGE DURATION OF A RECHARGEABLE BATTERY OF AN INFUSION PUMP

Abstract

A method for extending the storage lifetime of a rechargeable battery located in a device is disclosed. The battery lifetime extension method includes providing a device that derives its power from a rechargeable battery. When the device is powered off by a user, a computer implemented program utilized by the device automatically powers up the device into a lower power mode upon expiration of a variable duration timer monitored by the computing unit that continuously repeats according to a programed duration cycle. The computer implemented program then evaluates a state of charge of the rechargeable battery, determines whether the state of charge of the rechargeable battery is above or below a variable programed threshold, and causes the rechargeable battery to remain in a low power state until a charge is applied to the rechargeable battery.

Claims

1. An apparatus with battery control for extending a storage lifetime of a rechargeable battery, the apparatus comprising: a user interface; and a computing unit communicatively coupled to the user interface, the computing unit configured to execute a computer implemented program that causes the computing unit to: evaluate a state of charge of a rechargeable battery when the computing unit is powered in a low power mode from a lower power state after expiration of a variable duration timer, determine whether a remaining capacity of the rechargeable battery is above or below a variable programed threshold using the state of charge, cause the rechargeable battery to remain in an off or low power state until a charge is applied to the rechargeable battery after determining the remaining capacity of the rechargeable battery is below the variable programed threshold, and cause the rechargeable battery to wake after detection of an alternate power source.

2. The apparatus of claim 1, wherein the rechargeable battery, the user interface, and the computing unit are part of a peristaltic pump, a syringe pump, or an ambulatory pump.

3. The apparatus of claim 1, wherein the computing unit is configured to continuously evaluate the state of charge of the rechargeable battery according to a programed duration cycle.

4. The apparatus of claim 1, wherein the computing unit is configured to command the rechargeable battery to enter the lower power state after receiving a command via the user interface to manually power down.

5. The apparatus of claim 1, wherein the variable duration timer has a predetermined length that is between thirty minutes and 48 hours.

6. The apparatus of claim 1, wherein the variable programed threshold is between 0.5 Wh and 6.0 Wh.

7. The apparatus of claim 1, wherein the computer implemented program is further configured to cause the computing unit to: detect that at least one cell of the rechargeable battery is below a minimum cell voltage; and cause the rechargeable battery to disable.

8. The apparatus of claim 7, wherein the minimum cell voltage corresponds to 1.9 Wh of remaining capacity of the rechargeable battery.

9. The apparatus of claim 1, wherein the computing unit manages a device active state that is configured to consume 4 W, and wherein the low power mode consumes 30 mW and the off or low power state consumes 250 uW.

10. The apparatus of claim 9, wherein the off or low power state is a battery shutdown state.

11. The apparatus of claim 1, wherein the computer implemented program is configured to at least double a storage life of the rechargeable battery using the variable duration timer and by placing the rechargeable battery into the off or low power state after determining the remaining capacity of the rechargeable battery is below the variable programed threshold.

12. The apparatus of claim 1, wherein the alternate power source is a wall power source.

13. The apparatus of claim 1, wherein the computer implemented program is configured to cause the rechargeable battery to remain in the off or low power state by communicating a command to the rechargeable battery to remain in the off or low power state.

14. A battery control method for extending a storage lifetime of a rechargeable battery in a device that derives its power from the rechargeable battery, the device including a computing unit capable of executing a computer implemented program the method comprising: evaluating, using the computing unit, a state of charge of a rechargeable battery when the computing unit is powered in a low power mode from a lower power state after expiration of a variable duration timer; determining, using the computing unit, whether a remaining capacity of the rechargeable battery is above or below a variable programed threshold using the state of charge; causing, using the computing unit, the rechargeable battery to remain in an off or low power state until a charge is applied to the rechargeable battery after determining the remaining capacity of the rechargeable battery is below the variable programed threshold; and causing, using the computing unit, the rechargeable battery to wake after detection of an alternate power source.

15. The battery control method of claim 14, wherein causing the rechargeable battery to remain in the off or low power state including communicating, using the computing unit, a command to the rechargeable battery to remain in the off or low power state.

16. The battery control method of claim 14, wherein evaluating the state of charge of the rechargeable battery is performed continuously according to a programed duration cycle.

17. The battery control method of claim 14, further comprising causing, using the computing unit, the rechargeable battery to enter the lower power state after receiving a command from a user interface to manually power down.

18. The battery control method of claim 14, wherein the variable duration timer has a predetermined length that is between thirty minutes and 48 hours.

19. The battery control method of claim 14, wherein the variable programed threshold is between 0.5 Wh and 6.0 Wh.

20. The battery control method of claim 14, further comprising detecting, using the computing unit, that at least one cell of the rechargeable battery is below a minimum cell voltage; and causing, using the computing unit, the rechargeable battery to disable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 is a flow chart illustrating a currently known method for extending battery storage life.

[0035] FIG. 2 is a flow chart illustrating a method for extending the storage life of a rechargeable battery according to an embodiment of the present disclosure.

[0036] FIG. 3 is a diagram showing an example device configured to perform the method of FIG. 2, according to an example embodiment of the present disclosure.

DETAILED DESCRIPTION

[0037] The present disclosure provides a method for extending the lifetime of a rechargeable battery stored in a device. The provided method combines the benefits of passive battery management and the flexibility of computer implemented programs to arrive at a novel method for extending the longevity of a rechargeable battery stored in a device.

[0038] The disclosed method provides an extended duration of storage in a device without requiring the end user to perform any manual actions or separating the battery from the device while still allowing the device to turn on remotely, based on timers, or other electronic methods before the battery has too little energy to provide significant time of use. Since the device is disabled only when not in use and the battery is nearly depleted at the time this event is triggered, the device's battery run time is not affected.

[0039] FIG. 1 is a flow chart illustrating a currently known method 100 for extending battery lifetime. While the device storing the rechargeable battery is in use, at any time, the user may manually power down the device by pressing the power button. Even though the device is in a low power state, there is still drain on the cells. The battery drain comes from the device and battery manager electronics in the battery pack in addition to minimal drain due to battery cell self-discharge. A battery manager integrated circuit monitors battery pack parameters including current, cell, and pack voltages.

[0040] The battery manager integrated circuit continually monitors the cell and pack voltages as well as currents and determines the instantaneous and capacity remaining in the cells in addition to other parameters. These parameters can be queried from the battery monitor by the device at any time while the battery monitor is on. In this typical application, the method 100 begins when the device is in use (block 102). Typically, a user will operate the device when there is a sufficiently high state of charge. For example, the user operates the device when the state of charge is greater than 20%. Next, the user powers off the device or the device drains the battery to a fixed limit that causes the device to power off (block 104). At this point, the device transitions to a low power state (block 106). At this state, the device can be powered on by the user still using battery power.

[0041] In the low power state, the battery cells of the device drain at a nominal rate (block 108). The drain may be due to current draw from some components of the device, the battery manager integrated circuit (which is still on), and cell self-discharge. The battery manager integrated circuit determines if a change is applied, such as recharging from a wall power source (block 110). If a charge is applied, the method 100 returns to block 102 where the device is in use. If a charge is not applied, the compares a level of the cell voltages to a threshold (block 114). If the voltage level of the cells is above the threshold, the method 100 returns to block 108 where the battery continues to experience nominal drain. When the voltage level of the batter cells falls below the threshold (e.g., a low voltage threshold), the battery manager integrated circuit disables power to avoid damaging the cells (block 114). Further, the battery output and the battery manager integrated circuit is turned off (block 116). At this point, the battery cells experience minimal drain (block 118). However, power is still drained from the battery in the form of self-discharge, with a significantly reduced drain from the battery manager integrated circuit and no drain from the device. At this time, the safe storage duration is shorter than is needed by a user. To exit this mode, a voltage must be applied to the battery manager from the device via an alternate power source. If a charge is not applied and the cell voltage of the battery drops below a minimum cell voltage (e.g., a minimum drain threshold) at which the battery is not capable of being charged, the battery manager disables charging, which effectively disables the pack permanently for safety.

[0042] If a charge is applied (block 120), the method 100 returns to block 102. If a charge is not applied, it is determined if any of the battery cells have a voltage level that is less than a minimum voltage threshold (block 122). If the battery cells have voltage levels that are greater than the minimum voltage threshold, the method 100 returns to block 120 to check if a charge has been applied. If at least one of the battery cells has a voltage that is less than the minimum voltage threshold, the battery back is permanently disabled since at this point the at least one battery cell is damaged and will not charge effectively (block 124). The method 100 then ends.

[0043] FIG. 2 is a flow chart illustrating a method 200 for extending the storage life of a rechargeable battery, according to an embodiment of the present disclosure. While a device is in use (block 202), the device derives its power from the battery and is in communication with the battery. The communication method can include any serial, parallel or signal. At any time during the operation of the device, the user may manually power down the device by pressing the power button (block 204). Alternatively, the device powers off after the battery is drained to a fixed limit. Upon the device being manually powered down by the user, the battery output remains on and a computer implemented program run by the device transitions itself to a lower power state and initiates a timer set to expire after a predetermined length of time (block 206). In an embodiment, the predetermined length of the timer is approximately 12 hours. In another embodiment, the predetermined length of the timer is less than 12 hours. In another embodiment, the predetermined length of the timer is greater than 12 hours. For example, the predetermined length of the timer may be as short as 30 minutes and as long as 48 hours.

[0044] At this point, the battery cells experience nominal drain (block 208). The drain may be due to current draw from some components of the device, the battery manager integrated circuit (which is still on), and cell self-discharge. When the predetermined length of time expires and the timer terminates, the device commands itself to at least partially power on, out of its resting state (block 210). While in this state, the battery is drained by the device, the battery manager integrated circuit and self-discharge of the battery cell. In the timer triggered powered on state (e.g., a lower power mode), the device runs a query of the remaining capacity of the battery to determine if the remaining capacity of the battery is either greater than or less than a predetermined threshold (block 212). In an embodiment, the predetermined remaining capacity threshold is approximately less than 3.0 watt-hours (Wh). In another embodiment, the predetermined remaining capacity threshold is approximately 3.0 Wh. In yet another embodiment, the predetermined remaining capacity threshold is approximately greater than 3.0 Wh. For example, the predetermined remaining capacity threshold may be as low as 0.5 watt-hours and as great as 6.0 Wh.

[0045] If the query of the battery determines that the remaining capacity is less than or equal to the predetermined threshold, the battery is commanded to turn off all output and to turn off battery monitoring integrated circuits (block 214). In this state, the battery is being drained primarily through battery cell self-discharge with the battery manager integrated circuit load secondary and no pump load (block 216). To exit this mode, a voltage must be applied to the battery manager from the device via an alternate power source. If a charge is not applied and the cell voltage of the battery drops below a minimum cell voltage at which the battery is not capable of being charged, the battery manager disables charging, which effectively disables the pack permanently for safety.

[0046] If a charge is applied (block 218), the method 200 returns to block 202. If a charge is not applied, it is determined if any of the battery cells have a voltage level that is less than a minimum voltage threshold (block 220). If the battery cells have voltage levels that are greater than the minimum voltage threshold, the method 200 returns to block 218 to check if a charge has been applied. If at least one of the battery cells has a voltage that is less than the minimum voltage threshold, the battery back is permanently disabled since at this point the at least one battery cell is damaged and will not charge effectively (block 222). The method 200 then ends.

[0047] Returning to block 212, if the remaining capacity query determines that the remaining capacity of the battery is greater than or equal to the predetermined threshold, the device returns to the low power state until the timer expires again. The battery manager integrated circuit continues to monitor battery parameters. In this state the device can be powered on as normal by the user. If an alternate power source is applied to the device, it will turn on and charge the battery.

[0048] In some embodiments, the battery manager integrated circuit may have a cell under-voltage (CUV) feature. However, in all cases the device will have turned off the battery manager and battery output before it reaches this threshold. Compared to the method 100, in the method 200 this lowest power consumption state begins earlier with more remaining capacity in the cells which prolongs the storage duration. This benefit is reduced if the user of the device drains the battery to the user limit. However there is still improvement in storage duration even in this extreme case.

[0049] FIG. 3 is a diagram showing an example device 300 configured to perform the method 200 of FIG. 2, according to an example embodiment of the present disclosure. The device 300 may be an infusion pump, a dialysis machine, or other medical device. The infusion pump in various embodiments is a peristaltic pump, a syringe pump, or an ambulatory pump configured to deliver a medication to a patient. It should be appreciated that the device 300 is in various embodiments, may include any type of medical device, or any other suitable device having a rechargeable battery.

[0050] The device 300 of FIG. 3 includes a rechargeable battery 302 having one or more battery cells. The rechargeable battery 302 may include battery manager electronics 304 for monitoring current and/or voltage levels of the battery cells. The battery manager electronics 304 may also disable the rechargeable battery 302 when at least a voltage level of one of the cells falls below a minimum voltage threshold. In some embodiments, the battery manager electronics 304 may include the battery manager integrated circuit discussed in conjunction with FIG. 2.

[0051] The device 300 also includes a computing unit 306 and a memory device 308. The computing unit 306 may include a processor, application specific integrated circuit, microcontroller, logic controller, etc. The memory device 308 includes any solid state or flash drive. The memory device 308 includes a computer implemented program 310 (e.g., computer-readable instructions) that is executable by the computing unit 306 to perform at least the method 200 of FIG. 2. In some embodiments, the battery manager electronics 304 may be included within the computing unit 306.

[0052] The computing unit 306 may also control operation of the device 300. For example, the computing unit 306 controls one or more pumps or valves in an actuation area 312 that operate on an intravenous tube to pump a fluid or a drug from a container to a patient. The device 300 also includes an interface 314, such as buttons including a power on/off button. The interface 314 is configured to receive user-specified commands for the device 300. The device 300 may also include a display screen 316 for showing information related to an operation of the device 300 or a treatment provided by the device 300. The display screen 316 may include a touchscreen.

[0053] In one embodiment, the infusion pump device 300 has the following states: a device active state that consumes 4 W, a device shutdown state that consumes 30 mW, and a battery shutdown state that consumes 250 uW. In one embodiment, the device battery 302 has the following states: a device usable state having a capacity above 0 Wh, a reserved capacity state having a capacity between 0 Wh to 1.0 Wh, and cell protection state (permanently disabled) that is below 1.9 Wh of remaining capacity.

[0054] Under the current known method 100 shown in FIG. 1, if a user is allowed to deplete the battery at 4 W per hour to a remaining capacity of 0 Wh, the device will then transition to the device shutdown state for approximately 1.4 days, this is followed by the battery transitioning to the battery shutdown state for approximately 150 days. Under the new disclosed method 200 shown in FIG. 2, in the worst case the user is allowed to deplete the battery at 4 W per hour to a remaining capacity of 0 Wh. The device will then transition directly to battery shutdown state for approximately 317 days based on self-discharge. Under the new disclosed method 200 shown in FIG. 2, in the best case the user will manually turn the device off with greater than 3 Wh remaining. The device 300 will then transition directly to the battery shutdown state for approximately 817 days based on self-discharge. It should be appreciated that other limiting factors unrelated to over-discharge may limit actual storage time to approximately 2 years.

CONCLUSION

[0055] It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.