In-situ battery health detector and end-of-life indicator

• US 8,415,926 B2
• Filed: 10/19/2009
• Issued: 04/09/2013
• Est. Priority Date: 10/19/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Bhardwaj, Ramesh C., Hwang, Taisup, Mank, Richard M.
• Primary Examiner(s): Tso, Edward
• Assistant Examiner(s): BOATENG, ALEXIS ASIEDUA
• Application Number:
  US12/581,721
• Publication Number:
  US 20110089907A1
• Time in Patent Office: 1,268 Days
• Field of Search: 320/134, 320/135, 320/136, 320/132, 320/127, 320/128, 320/129, 320/137, 320/139, 320/148, 320/149, 320/156, 320/157, 320/161, 320/162, 320/164, 324/425, 324/426, 324/427, 324/428, 324/429, 324/430, 324/431, 324/432, 324/434, 324/435, 324/436
• US Class Current: 320/134
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• 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: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Some embodiments provide a system that monitors a battery in a portable electronic device. During operation, the system applies a pulse load to the battery and determines an impedance of the battery by measuring a voltage of the battery during the pulse load. Next, the system assesses a health of the battery based on the impedance. Finally, the system uses the assessed health to manage use of the battery in the portable electronic device.

Claims

1. A computer-implemented method for monitoring a battery in a portable electronic device, comprising:

applying a pulse load to the battery;

determining an impedance of the battery by measuring a voltage of the battery during the pulse load;

assessing a health of the battery based on the impedance by analyzing a linearity of the impedance of the battery for at least two separate charge-discharge cycles performed on the battery; and

using the assessed health to manage use of the battery in the portable electronic device.

2. The computer-implemented method of claim 1, wherein determining the impedance of the battery involves:

measuring the voltage of the battery in a fully charged state;

calculating a drop in the voltage after the pulse load is applied; and

dividing the drop in the voltage by a current of the pulse load.

3. The computer-implemented method of claim 1, wherein a lack of linearity corresponds to degradation in the battery.

4. The computer-implemented method of claim 1, wherein using the assessed health to manage use of the battery in the portable electronic device involves at least one of:

adjusting a charge voltage for the battery;

notifying a user of the portable electronic device of an end-of-life for the battery; and

isolating a cell in the battery.

5. The computer-implemented method of claim 4, wherein adjusting the charge voltage for the battery involves:

decreasing the charge voltage to extend a cycle life of the battery and to control cell swelling within the battery.

6. The computer-implemented method of claim 4, wherein adjusting the charge voltage for the battery involves:

stopping charging of the battery at the end-of-life for the battery.