Method for determination of the charge drawn by an energy storage battery

• US 20040160215A1
• Filed: 11/12/2003
• Published: 08/19/2004
• Est. Priority Date: 11/14/2002
• Status: Active Grant

• Current Assignee: VB Autobatterie GmbH
• Original Assignee: VB Autobatterie GmbH
• Inventors: Richter, Gerolf, Koch, Ingo
• Granted Patent: US 7,375,495 B2
• Time in Patent Office: Days
• US Class Current: 320/132
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables

Abstract

A method for determining the charge drawn by an energy storage battery starting from an initial state of charge at the start of the drawing of the charge includes determining the charge drawn as a function of an exponential function with a time constant. The time constant is defined at least as a function of the energy storage battery type and of the temperature of at least one of the battery temperature and the electrolyte temperature. The method may be carried out utilizing a monitoring device or a computer program.

Claims

1. A method for determining the charge drawn by an energy storage battery starting from an initial state of charge at the start of the drawing of the charge, the method comprising:

determining the charge drawn as a function of an exponential function with a time constant, wherein the time constant is defined at least as a function of the energy storage battery type and of the temperature of at least one of the battery temperature and the electrolyte temperature.

2. The method of claim 1 wherein the time constant is also defined as a function of the state of charge at the start of the drawing of the charge.

3. The method of claim 2 wherein the time constant is also defined as a function of at least one of a charging voltage, a mean charging voltage and a rated charging voltage.

4. The method of claim 1 further comprising determining the absolute amount of charge drawn according to the function

Δ

Q≈

(1−

e<sup>−

t/τ</sup>

) (Q₀−

Q_s),

 

where Δ

Q is the absolute amount of charge drawn, Q₀ is the defined rated capacity of the energy storage battery, and Q_s is the initial charge of the energy storage battery at the start of the drawing of the charge.

5. The method of claim 1 further comprising determining the relative state of charge of the energy storage battery with respect to the rated capacity of the energy storage battery according to the function:

Q(t)/Q₀≈

1−

(1−

Q_s/Q₀)<sup>−

t/τ</sup>

where Q (t)/Q₀ is the relative state of charge of the energy storage battery, Q₀ is the rated capacity of the energy storage battery, and Q_s is the initial charge of the energy storage battery at the start of the drawing of the charge.

6. The method of claim 1 further comprising determining a first correction factor for the time constant, the first correction factor being determined using the formula:

τ

_T=a<sup>−

(T_e−

Te,0)/b</sup>

where τ

_T is the first correction factor, T_e is the electrolyte temperature of the energy storage battery, T_e,0 is a defined electrolyte nominal temperature, and a and b are constants.

7. The method of claim 6 wherein the constant a has a value between 1.5 and 2.5 and the constant b has a value between 9 and 11.

8. The method of claim 6 further comprising determining a second correction factor for the time constant, the second correction factor having a value between 1 and 1−

Q_s/Q₀.

9. A monitoring device for energy storage batteries comprising:

a device for measuring battery temperature; and

a computation device for determining the charge drawn by an energy storage battery starting from an initial state of charge at the start of the drawing of the charge;

wherein the computation device is designed to carry out a method comprising;

determining the charge drawn as a function of an exponential function with a time constant, wherein the time constant is defined at least as a function of the energy storage battery type and of the temperature of at least one of the battery temperature and the electrolyte temperature.

10. A computer program comprising:

computer program code designed to carry out a method when the computer program is run using a processor device, the method comprising;

determining the charge drawn by an energy storage battery as a function of an exponential function with a time constant, wherein the time constant is defined at least as a function of the energy storage battery type and of the temperature of at least one of the battery temperature and the electrolyte temperature.

11. The computer program of claim 10 wherein the computer program is a program file stored on a data storage medium.