Method for determining the performance of a storage battery

• US 6,534,992 B2
• Filed: 02/07/2002
• Issued: 03/18/2003
• Est. Priority Date: 02/17/2001
• Status: Expired due to Term

• Current Assignee: Clarios Germany GmbH & Co. KG (Michael Tojner, PhD, LLD)
• Original Assignee: VB Autobatterie GmbH
• Inventors: Meissner, Eberhard, Koch, Ingo
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US10/071,637
• Publication Number:
  US 20020113593A1
• Time in Patent Office: 404 Days
• Field of Search: 320/134, 320/136, 324/426, 324/427, 324/430, 324/431, 324/433
• US Class Current: 324/426
• CPC Class Codes: G01R 31/3647 for determining the ability of a battery to perform a critical function, e.g. cranking
• CPC Class Codes: G01R 31/386 using test-loads
• CPC Class Codes: G01R 31/388 involving voltage measurements
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health

Abstract

A method for determining performance of a storage battery including evaluating a time profile of voltage drop in the storage battery by application of a heavy current load, determining a voltage A from voltage response U(t) of the storage battery after switching on the heavy current load, determining a state value A1 from the voltage value A, battery temperature T_BAT and state of charge SOC, comparing state value A1 with a preset value A1_x which depends at least on associated battery temperature (T_BAT) and associated state of charge (SOC) of the storage battery, wherein the present value A1_x is calculated from comparison values A1_T which are determined from the state values A1 for previous heavy current loads applied to the storage battery, and determining performance of the storage battery from the difference between the present value A1_x and the state value A1.

Claims

1. A method for determining performance of a storage battery comprising:

evaluating a time profile of voltage drop in the storage battery by application of a heavy current load;

determining a voltage A from voltage response U(t) of the storage battery after switching on the heavy current load;

determining a state value A1 from the voltage value A, battery temperature T_BAT and state of charge SOC;

comparing state value A1 with a preset value A1_x which depends at least on associated battery temperature T_BAT and associated state of charge SOC of the storage battery, wherein the present value A1_a is calculated from comparison values A1_T which are determined from the state values A1 for previous heavy current loads applied to the storage battery; and

determining performance of the storage battery from the difference between the present value A1_x and the state value A1.

2. The method as claimed in claim 1, wherein a minimum of the voltage response is selected as the voltage value A.

3. The method as claimed in claim 1, wherein the state value A1 is selected to be substantially equal to the voltage value A.

4. The method as claimed in claim 1, wherein in the state value A1 is determined from the voltage response of the storage battery with a heavy current load and from at least one variable selected from the group consisting of inductance, capacitance and resistance of an associated circuit.

5. The method as claimed in claim 1, wherein the comparison values A1_T are determined from storage battery voltage responses U(t) obtained from previous heavy current loads in a selected time period.

6. The method as claimed in claim 1, wherein the preset value A1_x is determined by interpolation or extrapolation from the comparison values A1_T.

7. The method as claimed in claim 1, wherein the voltage response U(t) is used to determine a number of state values A11, A12, . . . , wherein these state values A11, A12, . . . are compared with preset values A1_x1, A1_x2, . . . which depend at least on the associated battery temperature T_BAT and the associated state of charge SOC of the storage battery, with the preset values A1_x1, A1_x2, . . . having been calculated from the comparison values A1_T1, A1_T2, . . . which were determined from state values A11, A12, . . . from previous heavy current loads, and wherein weighted differences (A1_x1−

A11), (A1_x2−

A12), . . . between the preset values A1_x1, A1_x2 and the measured state values A11, A12, . . . are used to determine the performance of the storage battery.

8. The method as claimed in claim 1, further comprising:

linking the performance of the storage battery to a result from another method for determining the state of charge, performance, availability or age of the storage battery; and

displaying the result of the linking, or a variable derived from it.

9. The method as claimed in claim 1, wherein a conversion to value A1* for a selected given SOC* and a selected temperature T_BAT* is carried out from comparison values A1_T by using information about a functional relationship between the values A1_T and as a function of SOC and T_BAT, for all state values A1 obtained, whose state of charge SOC and battery temperature T_BAT do not correspond to SOC* and T_BAT*, and wherein the present performance for SOC* and T_BAT* is determined from the magnitude of this state value A1*, for SOC* and T_BAT*.

10. The method as claimed in claim 1, wherein a limit value A1_L of the state value is predetermined for the performance of the storage battery for a defined state of charge SOC_L and a defined battery temperature T_BATL, wherein a conversion to a value A1* for SOC_L and T_BATL is carried out for all those state values A1 obtained whose state of charge SOC and battery temperature T_BAT do not correspond to those for the limit value A1_L, wherein present performance for SOC_L and T_BATL is determined from the magnitude of this state value A1* for SOC_L and T_BATL as the ratio to the limit value A1_L for SOC_L and T_BATL, and wherein the ratio is used as a measure for instantaneous performance of the storage battery.

11. The method as claimed in claim 1, wherein the performance of the storage battery determined is used to control auxiliary functions.