Methods and system for a battery

1. An apparatus for monitoring a battery, comprising:

a timer configured to measure an elapsed time from a starting time;

a measurement circuit configured to compute a remaining capacity of the battery;

a temperature sensor configured to measure a temperature of the battery;

a memory configured to store:

an initial full charge capacity value of the battery; and

known data of faded capacity values of the battery as a function of time, temperature, and remaining capacity; and

a logic circuit configured to:

compute an updated full charge capacity value based on:

the initial full charge capacity value;

the measured elapsed time;

the computed remaining capacity;

the measured temperature; and

the known capacity values;

compute the state of health of the battery, wherein the state of health of the battery is defined by a ratio of the updated full charge capacity value and the initial full charge capacity value; and

transmit the computed state of health to the memory.

2. The apparatus according to claim 1 , wherein the initial full charge capacity value is a capacity of the battery at the starting time.

3. The apparatus according to claim 1 , wherein the known data comprises a first profile table comprising faded capacity values as a function of time.

4. The apparatus according to claim 3 , wherein the logic circuit is further configured to determine a first fade ratio based on the first profile table.

5. The apparatus according to claim 1 , wherein the known data comprises a second profile table comprising faded capacity values as a function of temperature.

6. The apparatus according to claim 5 , wherein the logic circuit is further configured to determine a second fade ratio based on the second profile table.

7. The apparatus according to claim 1 , wherein the known data comprises a third profile table comprising faded capacity values as a function of remaining capacity.

8. The apparatus according to claim 7 , wherein the logic circuit is further configured to determine a third fade ratio based on the first profile table.

9. The apparatus according to claim 1 , further comprising a cycle counter, wherein the cycle counter counts a number of charge/discharge cycles of the battery.

10. The apparatus according to claim 1 , wherein the memory further comprises faded capacity values as a function of charge/discharge cycles.

11. A method for monitoring a battery, comprising:

measuring an elapsed time from a starting time;

computing a remaining capacity of the battery;

measuring a temperature of the battery; and

computing an updated full charge capacity value based on:

an initial full charge capacity value, wherein the initial full charge capacity value is a capacity of the battery at the starting time;

a first fade ratio, wherein the first fade ratio is a function of the measured elapsed time;

a second fade ratio, wherein the second fade ratio is a function of the measured temperature; and

a third fade ratio, wherein the third fade ratio is a function of the computed remaining capacity; and

estimating a state of health of the battery based on the updated full charge capacity value.

12. The method according to claim 11 , further comprising counting a number of charge/discharge cycles of the battery.

13. The method according to claim 12 , wherein computing the updated full charge capacity value is also based on the number of counted charge/discharge cycles of the battery.

14. A system, comprising:

a battery;

a temperature sensor to detect a temperature of the battery; and

a fuel gauge circuit connected to the battery and the temperature sensor, and configured to:

measure an elapsed time from a starting time;

compute a remaining capacity of the battery at the elapsed time;

measure a temperature of the battery at the elapsed time;

compute an updated full charge capacity (UFCC) value at the elapsed time based on:

known data of faded capacity values of the battery as a function of time, temperature, and remaining capacity;

an initial full charge capacity (IFCC) value, wherein the IFCC value is a capacity of the battery at the starting time;

the measured elapsed time;

the computed remaining capacity; and

the measured temperature of the battery at the elapsed time; and

estimate a state of health of the battery based on the computed UFCC value.

15. The system according to claim 14 , wherein the known data comprises:

a first profile table comprising the faded capacity values as a function of time;

a second profile table comprising the faded capacity values as a function of temperature; and

a third profile table comprising the faded capacity values as a function of remaining capacity.

16. The system according to claim 15 , wherein the fuel gauge is further configured to determine:

a first fade ratio based on the first profile table;

a second fade ratio based on the second profile table; and

a third fade ratio based on the third profile table.

17. The system according to claim 14 , wherein the fuel gauge is further configured to count a number of charge/discharge cycles of the battery.

18. The system according to claim 17 , wherein the UFCC value is also based on known data of faded capacity values as a function of the number of counted charge/discharge cycles.