Smart battery odometer

• US 5,627,453 A
• Filed: 01/11/1995
• Issued: 05/06/1997
• Est. Priority Date: 01/11/1995
• Status: Expired due to Fees

• Current Assignee: Dell USA LP (Dell Technologies Inc.)
• Original Assignee: Dell USA LP (Dell Technologies Inc.)
• Inventors: Sheehan, Ed, Thompson, Leslie
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US08/372,277
• Time in Patent Office: 846 Days
• Field of Search: 320/5, 320/12, 320/13, 320/30, 320/31, 320/35, 320/39, 320/48, 320/43
• US Class Current: 320/134
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10S 320/18 Indicator or display

Abstract

A rechargeable battery pack including a microcontroller connected to a voltage measuring circuit and a current measuring circuit for measuring, respectively, the voltage across and the current flowing from a battery. Upon each expiration of a predefined time period during each discharge cycle of the battery, the microcontroller computes the product of the voltage, the current, and the length of the time period, thereby computing the energy expended by the battery over each period of time. An energy variable stored in a nonvolatile memory device associated with the microcontroller for representing the total amount of energy output by the battery over the life thereof is incremented by the computed energy. In one embodiment, a temperature sensing circuit measures the temperature of the battery and the instantaneous energy is adjusted by a temperature factor associated by the measured temperature before being used to increment the value of the energy variable.

Claims

1. A battery pack assembly for a rechargeable battery, comprising:

a microcontroller;

a memory device electrically connected to said microcontroller for storing a number representing a total quantity of energy output by said battery throughout its life;

a voltage measuring circuit for measuring a voltage across said battery and, generating to said microcontroller signals indicative of said measured voltage;

a current measuring circuit for measuring a current output by said battery and generating to said microcontroller signals indicative of said measured current;

said microcontroller being operative, upon each elapse of a predetermined time period during each discharge cycle of said battery, for computing a product of said measured voltage, said measured current, and a length of said time period, said computed product being indicative of an mount of energy output by said battery during said time period, and incrementing said stored number by said computed product.

2. The assembly of claim 1 wherein said microcontroller is electrically connected to a computer having a display, said microcontroller being further operative for outputting to said computer said stored number for presentation on said display.

3. The assembly of claim 1 wherein said microcontroller is electrically connected to a computer having a display, said microcontroller being further operative for outputting to said computer said stored number for further processing by said computer.

4. The assembly of claim 1 further comprising:

a temperature sensor for measuring a temperature of said battery and outputting to said microcontroller signals indicative of said measured temperature;

said microcontroller being further operative, upon each elapse of said predetermined time period during each discharge cycle of said battery, for determining a temperature factor associated with said measured temperature and adjusting said computed product by said temperature factor prior to incrementing said stored number by said computed product.

5. The assembly of claim 1 further comprising:

a temperature sensor for measuring a temperature of said battery during said time period and outputting to said microcontroller signals indicative of said measured temperature;

wherein said microcontroller is further operative, upon each elapse of said predetermined time period during each charging cycle of said battery, for determining whether said measured temperature falls outside a predefined optimum range of temperatures and, responsive to a determination that said measured temperature falls outside said predefined optimum range, for computing an absolute value of a product of said measured voltage, said measured current, said time period length and a degradation factor corresponding to said measured temperature and incrementing said stored number by said absolute value.

6. A battery pack assembly for a rechargeable battery, comprising:

a microcontroller;

a memory device electrically connected to said microcontroller for storing a number representing a total quantity of energy output by said battery throughout its life;

a voltage measuring circuit for measuring a voltage across said battery and, generating to said microcontroller a signal indicative of said measured voltage;

a current measuring circuit for measuring a current output by said battery and generating to said microcontroller a signal indicative of said measured current;

a temperature sensor for measuring a temperature of said battery and outputting to said microcontroller signals indicative of said measured temperature;

said microcontroller being operative, upon each elapse of a predetermined time period during each discharge cycle of said battery, for computing a product of said measured voltage, said measured current, a temperature factor corresponding to said measured temperature and a length of said time period, said computed product being indicative of an amount of energy output by said battery during said time period, and incrementing said stored number by said computed product.

7. The assembly of claim 6 wherein said microcontroller is electrically connected to a computer having a display, said microcontroller being operative to output to said computer said stored number for presentation on said display.

8. The assembly of claim 6 wherein said microcontroller is electrically connected to a computer, said microcontroller being operative to output to said computer said stored number for further processing by said computer.

9. The assembly of claim 6 further comprising a periodic timer having an output connected to an input of said microcontroller for generating signals to said microcontroller indicative of each elapse of said predetermined time period.

10. The assembly of claim 6 wherein said microcontroller is further operative, upon each elapse of said predetermined time period during each charging cycle of said battery, for determining whether said measured temperature falls outside a predefined optimum range of temperatures and, responsive to a determination that said measured temperature falls outside said predefined optimum range, for computing an absolute value of a product of said measured voltage, said measured current, said time period length and a degradation factor corresponding to said measured temperature, and incrementing said stored number by said determined absolute value.

11. A battery pack assembly for a rechargeable battery, comprising:

means for storing a number representing a total quantity of energy output by said battery throughout its life;

means for measuring a voltage across said battery and generating signals indicative of said measured voltage;

means for measuring a current output by said battery and generating signals indicative of said measured current;

means operative upon each elapse of a predetermined time period during each discharge cycle of said battery for computing a product of said measured voltage, said measured current, and a length of said time period, said computed product being indicative of an amount of energy output by said battery during said time period, and incrementing said stored number by said computed product.

12. The assembly of claim 11 further comprising means for displaying said stored number.

13. The assembly of claim 11 further comprising:

means for measuring a temperature of said battery; and

means for adjusting said computed product by a temperature factor associated with said measured temperature prior to incrementing said stored number.

14. The assembly of claim 13 further comprising:

means operative upon each elapse of said predetermined time period during each charging cycle of said battery for determining whether said measured temperature falls outside a predefined optimum range of temperatures and, responsive to a determination that said measured temperature falls outside said predefined optimum range, for computing an absolute value of a product of said measured voltage, said measured current, said time period length and a degradation factor corresponding to said measured temperature and incrementing said stored number by said absolute value.

15. A method for tracking an amount of energy output by a battery during its lifetime, the method comprising:

prior to a first use of said battery, initializing a memory location for storing a number representing a total quantity of energy output by said battery during its life; and

upon each elapse of a predetermined time period, measuring a voltage potential across said battery and measuring a current output by said battery;

upon each elapse of said predetermined time period during each discharge cycle of said battery;

computing a product of said measured voltage, said measured current, and a length of said time period; and

incrementing said stored number by said product such that, at all times throughout said battery life, said stored number is equal to a total amount of energy output by said battery; and

periodically displaying said stored number.

16. The method of claim 15 further comprising, upon each elapse of said predetermined time period during each discharge cycle of said battery:

measuring a temperature of said battery; and

adjusting said computed product by a temperature factor associated with said measured temperature prior to said incrementing.

17. The method of claim 15 further comprising, upon each elapse of said predetermined time period during each charging cycle of said battery:

measuring a temperature of said battery;

determining whether said measured temperature falls outside a predefined optimum range of temperatures; and

responsive to a determination that said measured temperature falls outside said predefined optimum range;

computing an absolute value of a product of said measured voltage, said measured current, said time period length and a degradation factor corresponding to said measured temperature; and

incrementing said stored number by said absolute value.

18. A method for tracking an amount of energy output by a battery during its lifetime, the method comprising:

prior to a first use of said battery, initializing a memory location for storing a number representing a total quantity of energy output by said battery during its life; and

upon each elapse of a predetermined time period;

measuring a voltage potential across said battery;

measuring a current output by said battery; and

measuring a temperature of said battery;

upon each elapse of said predetermined time period during each discharge cycle of said battery;

computing a product of said measured voltage, said measured current, a length of said time period, and a temperature factor corresponding to said measured temperature; and

incrementing said stored number by said product such that, at all times throughout said battery life, said stored number is equal to a total amount of energy output by said battery; and

periodically displaying said stored number.

19. The method of claim 18 further comprising, upon each elapse of said predetermined time period during each charging cycle of said battery:

determining whether said measured temperature falls outside a predefined optimum range of temperatures; and

responsive to a determination that said measured temperature falls outside said predefined optimum range;

computing an absolute value of a product of said measured voltage, said measured current, said time period length and a degradation factor corresponding to said measured temperature; and

incrementing said stored number by said absolute value.

20. The method of claim 18 further comprising outputting said stored number to a computer for further processing.