Method for displaying a "low battery" state in electrical equipment with electrical energy stores and electrical equipment with electrical energy stores with means for displaying a "low battery" state

• US 6,121,754 A
• Filed: 06/05/1998
• Issued: 09/19/2000
• Est. Priority Date: 12/15/1995
• Status: Expired due to Term

• Current Assignee: Gigaset Communications GmbH (Gigaset AG)
• Original Assignee: Siemens AG
• Inventors: Kamperschroer, Erich
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US09/077,708
• Time in Patent Office: 837 Days
• Field of Search: 320/132, 320/134, 320/128, 320/130
• US Class Current: 320/132
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• 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: H04M 1/73 Battery saving arrangements
• CPC Class Codes: H04M 19/08 with current supply sources at the substations generating ringing current H04M19/04
• CPC Class Codes: H04W 52/0261 managing power supply demand, e.g. depending on battery level
• CPC Class Codes: Y02D 30/70 in wireless communication networks
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

In an electrical device, for example a cordless mobile part (MT_me), having an electrical energy store (AKK), for example a rechargeable battery or a battery, in order to indicate neither too early nor too late the "low energy store" state in the interest of utilizing the stored energy optimally and in a standard manner for various energy store types and/or different operating conditions of the energy store, use is made of the characteristic that the gradient at the "voltage knee" of a discharge voltage curve (ESK) of the energy store (AKK) is always the same, irrespective of the respective voltage level on the discharge voltage profile. In this case, at least one characteristic variable (STG, KRU)--for example the gradient, the curvature--is continually calculated in the form of an actual value (ISW, IKW) which indicates the characteristic variable in the discharge phase of the energy store. The calculation is in this case carried out, for example, by linear regression. If the actual value (ISW, IKW) is greater than a nominal value (SSW, SKW), then the "low energy store" state is signalled. This ensures that, irrespective of the nature of the energy store and the ambient temperature, the rechargeable battery and the mobile part (MT_me) always have approximately the same residual operating time.

Claims

1. A method for indicating a "low energy store" state in electrical devices having electrical energy stores, comprising the steps of:

determining by linear regression, during a discharge phase of the electrical energy store, a characteristic variable of the energy store;

calculating a curvature-related nominal value from the characteristic variable;

comparing the actual value with the nominal value;

indicating the "low energy store" state if the actual value differs from the nominal value.

2. The method as claimed in claim 1, wherein the characteristic variable is determined at regular time intervals.

3. The method as claimed in claim 1, wherein the characteristic variable is determined when a specified discharge curve value is undershot, the discharge curve value being specified such that a time at which the discharge curve value is undershot is approximately a time at which a "voltage knee" occurs in the discharge curve.

4. The method as claimed in claim 1, wherein the method is utilized in an electrical device having a rechargeable battery as the electrical energy store.

5. The method as claimed in claim 1, wherein the method is utilized in an electrical device having a battery as the electrical energy store.

6. The method as claimed in claim 1, wherein the method is utilized in a cordless mobile part.

14. The electrical device as claimed in claim 1, wherein the actual value is less than the nominal value.

15. The electrical device as claimed in claim 1, wherein the actual value is greater than the nominal value.

7. An electrical device having an electrical energy store for indicating a "low energy store" state, comprising:

first means for determining data which, during a discharge phase of the electrical energy store, determine a characteristic variable of the energy store as a curvature-related actual value;

the first means determining the characteristic variable by linear regression;

a memory in which a specified, curvature-related nominal value is stored;

second means for comparison of data, which are connected to the first means and to the memory and compare the actual value with the nominal value;

third means for indicating data, which are connected to the second means and to an indicating device and which indicate the "low energy store" state whenever the actual value differs from the nominal value (SKW).

8. The electrical device as claimed in claim 7, wherein, the first means, the second means and the third means and the memory are integrated and implemented in a microcontroller.

9. The electrical device as claimed in claim 7, wherein the first means determines the characteristic variable at regular time intervals.

10. The electrical device as claimed in claim 7, wherein the first means determines the characteristic variable when a predetermined discharge curve value is undershot, the discharge curve value being specified such that a time at which the discharge curve value is undershot is in a vicinity of a time at which a "voltage knee" occurs in the discharge curve.

11. The electrical device as claimed in claim 7, wherein the electrical energy store is a rechargeable battery.

12. The electrical device as claimed in claim 7, wherein the electrical energy store is a battery.

13. The electrical device as claimed in claim 7, wherein the electrical device is a cordless mobile part.

16. The electrical device as claimed in claim 7, wherein the actual value is less than the nominal value.

17. The electrical device as claimed in claim 7, wherein the actual value is greater than the nominal value.