Method and device for determining characteristics of an unknown battery

• US 20070216367A1
• Filed: 03/14/2007
• Published: 09/20/2007
• 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
• Granted Patent: US 7,692,410 B2
• Time in Patent Office: Days
• US Class Current: 320/132
• 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; 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; and

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

V.