Adaptive effective C-rate charging of batteries

Patent metadata

Field	Value
Publication number	US-9559543-B2
Application number	US-201313946577-A
Country	US
Kind code	B2
Filing date	Jul 19, 2013
Priority date	Jul 19, 2013
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

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.

First claim

What is claimed is:

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.

Assignees

• Apple Inc

Inventors

• Greening Thomas C
• Koller Jeffrey G
• Ungar P Jeffrey

Classifications

• H02J7/977

  of the battery · CPC title

• H02J7/933

  the cycle being controlled or terminated in response to electric parameters · CPC title

• H01M10/48

  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 title

• H02J7/0091 Primary

  Electricity · mapped topic

• H01M10/425 Primary

  Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing (printed circuits H05K1/00) · CPC title