 Shunt resistance device for monitoring battery state of charge |
| What is needed therefore, is a device that minimizes the length of the conductors that connect the ... |
|
| Battery state monitoring circuit |
| In order to solve the foregoing problem, according to the present invention, a circuit is added to ... |
|
| Current leakage detection in high voltage battery pack |
| The invention claimed is: 1. A method of detecting a current leakage path in a high voltage battery ... |
|
| Bandgap reference circuit |
| In accordance with the present invention, a self-starting bandgap reference circuit is provided. "S... |
|
| Battery charger where the charge current rate is set by a switch modulated with a variable duty cycle |
| To address the above-discussed deficiencies of the prior art, the present invention provides, for ... |
|
| Plural comparator indicator of battery voltage |
| What I claim is: 1. A battery charge capacity indicator for providing an indication of charge ... |
|
| Charge status indicator |
| This object is accomplished by a circuit arrangement for indicating the charge status of a battery ... |
|
| Method of determining and displaying battery charge status |
| OF EMBODIMENTS Referring first to FIG. 1 of the drawings, a load 2 is concerned to a battery (... |
|
|
Method for determining the state of charge of rechargeable batteries by integration of the amounts of current flowing during charging and discharging
| Details |
Inventors: Ullrich, Matthias; Folge, Hans-Walter; Schmitz, Claus;
Assignee: Varta Automotive Systems GmbH (DE)
Primary Examiner: Tibbits; Pia
Assistant Examiner:
Attorney, Agent or Firm: Foley & Lardner LLP
In a method for determining the state of charge of rechargeable batteries by integration of the amounts of current flowing during charging and discharging, a first state of charge value LZ.sub.A is determined by continuous integration of the rechargeable battery current. A second state of charge value LZ.sub.B is determined by measurement of the no-load voltage U.sub.0 after receiving or supplying a defined amount of charge Q which is sufficient in order to leave the region of the mixed potential of the electrodes and to reach a no-load voltage of the rechargeable battery, and by comparison of this measured no-load voltage U.sub.0 with empirically determined no-load voltage characteristics for the rechargeable battery. From the state of charge values obtained in this way, that state of charge value is chosen which is more reliable in the preceding operating conditions, with the assessment of LZ.sub.A taking into account in particular the charge throughput in the assessment of LZ.sub.B, in particular the amount of charge Q which has flowed. The amount of charge Q should be at least 1 to 40%, preferably 5 to 50%, of the rated capacity of the rechargeable battery. |
|
DETAILED DESCRIPTION Voltage U.
sub.
0L is the measured voltage when no current is flowing through the rechargeable battery, and which is produced after completion of a charging process.
Voltage U.
sub.
0E is the measured voltage when no current is flowing through the rechargeable battery and which occurs after completion of a discharge process.
The expression "no current flowing" means that the current is in a range between 0 and I.
sub.
10, where I.
sub.
10 corresponds to the current which is sufficient to charge a rechargeable battery to its rated capacity in 10 hours.
In the region between these two characteristics, the electrodes have a so-called "mixed potential", which is characterized by being a no-load potential rather than an equilibrium potential, with undefined interchange current densities between the individual reactions.
According to the invention, a number of state of charge values LZ are calculated continuously during operation of the battery.
A first state of charge LZ.
sub.
A, which is also referred to as a "bookkeeping" state of charge, is determined by integrating the current flowing through the rechargeable battery over time.
The value determined by this current integration can be improved by corrections.
For example, the measured rechargeable battery current can be weighted by a factor .
eta.
, which describes a charging efficiency which is itself in turn dependent on the state of charge, temperature and current.
As a further correction, the self-discharge of the rechargeable battery, which is dependent on the state of charge and the temperature, is permanently subtracted from the state of charge determined by integration.
According to an exemplary embodiment, the reliability of the first state of charge value LZ.
sub.
A is also assessed based on the time since a most recent calibration.
In addition, a further state of charge LZ.
sub.
B is determined from a correlation of no-load voltage characteristics.
The no-load voltage, which occurs either after charging the rechargeable battery with a defined amount of charge Q or after discharging a defined amount of charge Q from the rechargeable battery, is used to determine the second state of charge value
|
|
Electrical and Wave 
