Adaptive effective C-rate charging of batteries
The disclosed embodiments provide a system that manages use of a battery in a portable electronic device. During operation, the system obtains a voltage of the battery and a state-of-charge of the battery. Next, the system calculates an effective C-rate of the battery using the voltage and the state-of-charge. Finally, the system uses the effective C-rate to manage a charging process for the battery.
1. A method for managing use of a battery in a portable electronic device, comprising:
measuring a voltage of a battery using a voltage sensor;
obtaining a state-of-charge of the battery;
interpolating, using a computer, pre-characterized constant-current curves of the battery to determine a constant-current curve which contains the measured voltage and the obtained state of charge;
determining a present effective C-rate corresponding to the determined constant-current curve; and
varying a charging current applied to the battery to control the effective C-rate toward a target C-rate of the battery until a target voltage of the battery is reached.
2. The method of claim 1 , wherein each of the pre-characterized constant-current curves of the battery is based on a characterized behavior of the battery.
3. The method of claim 2 , wherein one or more of the pre-characterized constant-current curves comprises at least one of:
one or more charge curves; or
one or more discharge curves.
4. The method of claim 2 , wherein the characterized behavior of the battery is associated with at least one of:
a temperature of the battery; or
an age of the battery.
5. The method of claim 1 , further comprising:
after the voltage of the battery reaches the target voltage, charging the battery using a constant charging voltage until the effective C-rate reaches a C-rate limit.
6. The method of claim 5 , further comprising:
in response to the effective C-rate being equal to the C-rate limit, further charging the battery with the constant charging voltage to drive the effective C-rate to the target C-rate.
7. The method of claim 5 , further comprising:
terminating the charging of the battery after the effective C-rate has dropped below a charge-termination limit for a pre-specified period, the charge-termination limit being lower than the C-rate limit.
8. The method of claim 1 , wherein at least one of the pre-characterized constant-current curves is implemented in polar format.
9. A system for managing use of a battery in a portable electronic device, comprising:
a monitoring apparatus configured to:
measure a voltage of the battery;
obtain a state-of-charge of the battery;
interpolate, using a computer, pre-characterized constant-current curves of the battery to determine a constant-current curve which contains the measured voltage and the obtained state of charge;
determine a present effective C-rate corresponding to the determined constant-current curve; and
a management apparatus configured to:
vary a charging current applied to the battery to control the effective C-rate toward a target C-rate of the battery until a target voltage of the battery is reached.
10. The system of claim 9 , wherein each of the pre-characterized constant-current curves of the battery is based on a characterized behavior of the battery.
11. The system of claim 10 , wherein the characterized behavior of the battery is associated with at least one of:
a temperature of the battery; or
an age of the battery.
12. The system of claim 9 , wherein the management apparatus is further configured to:
after the voltage of the battery reaches the target voltage, charge the battery using a constant charging voltage until the effective C-rate reaches a C-rate limit.
13. The system of claim 12 , wherein the management apparatus is further configured to:
in response to the effective C-rate being equal to the C-rate limit, further charge the battery with the constant charging voltage to drive the effective C-rate to the target C-rate.
14. The system of claim 12 , wherein the management apparatus is further configured to:
terminate charging of the battery after the effective C-rate has dropped below a charge-termination limit for a pre-specified period, the charge-termination limit being lower than the C-rate limit.
15. A non-transitory computer-readable medium storing instructions that, when executed by a computer, cause the computer to:
measure a voltage of the battery;
obtain a state-of-charge of the battery;
interpolate pre-characterized constant-current curves of the battery to determine a constant-current curve which contains the measured voltage and the obtained state of charge;
determine a present effective C-rate corresponding to the determined constant-current curve; and
vary a charging current applied to the battery to control the effective C-rate toward a target C-rate of the battery until a target voltage of the battery is reached.
16. The non-transitory computer-readable medium of claim 15 , wherein each of the pre-characterized constant-current curves of the battery is based on a characterized behavior of the battery.
17. The non-transitory computer-readable medium of claim 16 , wherein one or more of the pre-characterized constant-current curves comprises at least one of:
one or more charge curves; or
one or more discharge curves.
18. The non-transitory computer-readable medium of claim 15 , wherein the instructions further comprise instructions to cause the computer to:
after the voltage of the battery reaches the target voltage, charge the battery using a constant charging voltage until the effective C-rate reaches a C-rate limit.
19. The non-transitory computer-readable medium of claim 18 , wherein the instructions further comprise instructions to cause the computer to:
in response to the effective C-rate being equal to the C-rate limit, further charge the battery with the constant charging voltage to drive the effective C-rate to the target C-rate.
20. The non-transitory computer-readable medium of claim 18 , the instructions further comprise instructions to cause the computer to:
terminate the charging of the battery after the effective C-rate has dropped below a charge-termination limit for a pre-specified period, the charge-termination limit being lower than the C-rate limit.
21. A method for managing use of a battery in a portable electronic device, comprising:
measuring a first voltage of a battery using a voltage sensor;
obtaining a state-of-charge of the battery;
interpolating, using a computer, a plurality of pre-characterized constant-current curves of the battery to determine a constant-current curve associated with the first voltage and the obtained state-of-charge;
determining a present effective C-rate of the battery corresponding to the determined constant-current curve, the effective C-rate of the battery indicative of a rate at which the battery being charged and corresponding to the first voltage;
varying a charging current applied to the battery to control the effective C-rate of the battery toward a first target C-rate of the battery, the first target C-rate of the battery corresponding to a second voltage; and
in response to the effective C-rate being equal to the first target C-rate, charging the battery using a constant charging voltage until the effective C-rate is equal to a second target C-rate, wherein the second target C-rate corresponds to a third voltage and wherein the second target C-rate is smaller than the first target C-rate.
22. The method of claim 21 , further comprising:
terminating the charging of the battery in response to the effective C-rate falling below a fourth target C-rate for a predetermined amount of time, wherein the fourth target C-rate is smaller than the second target C-rate.