Method and device for determining characteristics of an unknown battery

• US 7,692,410 B2
• Filed: 03/14/2007
• Issued: 04/06/2010
• Est. Priority Date: 03/14/2006
• Status: Active Grant

• Current Assignee: National University of Ireland Galway
• Original Assignee: National University of Ireland Galway
• Inventors: Zhu, Chunbo, Hurley, William Gerard, Lee, Chi Kwan, Coleman, Martin
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): Fantu; Yalkew
• Application Number:
  US11/717,702
• Publication Number:
  US 20070216367A1
• Time in Patent Office: 1,119 Days
• Field of Search: 320/139, 320/141, 320/145, 320/160
• US Class Current: 320/160
• CPC Class Codes: G01R 31/388 involving voltage measurements

Abstract

An apparatus for determining a rate of charge/discharge, C rate, or state of charge, SOC, of a battery having unknown characteristics comprises a circuit for applying at least a two-pulse current load to said battery. A change in voltage, ΔV, resulting from the application of the second or a subsequent pulse is used to determine the C rate of the battery as a function of ΔV. An Open Circuit Voltage, OCV, of the battery a time interval after the completion of the application of the second or subsequent pulse is used to determine the SOC of the battery as a function of OCV.

Claims

1. A method of determining a rate of charge/discharge, C rate, of a battery having unknown characteristics comprising:

applying at least a two-pulse current load to said battery;

measuring a change in voltage, Δ

V, only resulting from the application of one of the second or a subsequent pulse,

wherein said change in voltage is substantially equal to the difference between an open circuit voltage of the battery prior to the application of the second or subsequent pulse and a loaded circuit voltage resulting from the application of the second or subsequent pulse; and

determining the C rate of the battery as a function of Δ

V.

2. The method of claim 1 wherein said determining step comprises determining the C rate from a look-up table of values of Δ

V.

3. The method of claim 1 wherein said determining step comprises determining the C rate as a mathematical function of Δ

V.

4. The method of claim 1 further comprising determining a maximum capacity of the battery by dividing the applied current load by the determined C rate.

5. The method of claim 4 wherein the applied current load is a change in current from a first load current to a second load current and wherein said determining comprises determining a change in C rate as a function of said change in voltage.

6. The method of claim 1 further comprising:

comparing Δ

V with a benchmark; and

changing the value of the applied current load if Δ

V does not comply with the benchmark.

7. The method of claim 6 wherein said benchmark comprises an upper limit and a lower limit.

8. The method of claim 7, comprising:

responsive to Δ

V being greater than the upper limit, decreasing the current load, and

responsive to Δ

V being lower than the lower limit, increasing the current load.

9. The method of claim 1 comprising applying said current load pulse for an on-time of 10 secs and an off-time of 10 secs.

10. An apparatus for determining a rate of charge/discharge, C rate, of a battery having unknown characteristics comprising:

a circuit for applying at least a two-pulse current load to said battery;

a sensor for measuring a change in voltage, Δ

V, only resulting from the application of one of the second or a subsequent pulse,

wherein said change in voltage is substantially equal to the difference between an open circuit voltage of the battery prior to the application of the second or subsequent pulse and a loaded circuit voltage resulting from the application of the second or subsequent pulse; and

means for determining the C rate of the battery as a function of Δ

V.