Electricity: measuring and testing – Electrolyte properties – Using a battery testing device
Patent
1993-11-10
1995-02-28
Wieder, Kenneth A.
Electricity: measuring and testing
Electrolyte properties
Using a battery testing device
324431, 320 48, 340636, G01R 3136
Patent
active
053940890
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a battery monitoring system.
In the use of battery operated equipment, such as battery powered electric vehicles and standby power systems, it is desirable to monitor the battery in order to provide from time to time a prediction informing the user of the remaining capacity in the battery.
It is an object of the present invention to provide a battery monitoring system.
According to the present invention a battery monitoring system comprises,
first means for evaluating the level of instantaneous current drawn from a battery when supplying a load;
second means for evaluating the level of instantaneous battery voltage;
third means for computing from the output of the first and second means the level of instantaneous power delivered by the battery;
fourth means for determining a final battery voltage level at which the capacity of the battery is exhausted;
fifth means for evaluating from the output of the third and fourth means the estimated final battery current;
sixth means for calculating according to a first predetermined algorithm the total discharge duration of the battery according to the outputs of the fourth and fifth means;
seventh means for calculating according to a second predetermined algorithm the accumulated discharge duration according to the output of the first and second means;
eighth means for assessing the remaining discharge duration available from the battery from the outputs of the sixth and seventh means;
wherein said first predetermined algorithm comprises a hyperbolic equation having first co-efficients selected from a stored table of such first co-efficients by the output of the fourth means, and said second predetermined algorithm comprises a cubic equation having second co-efficients selected from a stored table of such second co-efficients by the output of said first means.
An embodiment of the present invention will now be described with reference to the accompany drawings in which:
FIG. 1 schematically illustrates a battery monitoring system according to the present invention; and
FIG. 2 illustrates two typical discharge curves, the upper set of curves illustrating a discharge rate of 15.5% of a 10 hour battery capacity, and the lower set of curves illustrating an 18% discharge rate, the solid lines reflecting data issued by the battery manufacturer and the broken lines reflecting evaluations using the cubic equation of box 17 of FIG. 1.
A battery monitoring system 10 in accordance with the present invention is illustrated in FIG. 1 and monitors the condition of battery 9 which is connected to supply a load 8. System 10 comprises a first evaluating arrangement 11 for evaluating the level of instantaneous current drawn from the battery 9, and a second evaluating arrangement 12 for evaluating the level of instantaneous battery voltage. The outputs of arrangements 11 and 12 are fed to a third arrangement 13 which computes the level of instantaneous power delivered by the battery. A fourth arrangement 14, in this embodiment containing a preset value, determines a final voltage level for the battery 9 when the capacity of the battery is exhausted and the outputs of arrangements 13 and 14 are delivered to a fifth arrangement 15 which evaluates the estimated final battery current. The output of arrangement 15, together with the output of arrangement 14, is delivered to a sixth arrangement 16 for calculating according to a first predetermined algorithm (as will be explained) the total discharge duration of the battery 9.
The outputs of the first and second arrangements 11, 12, in addition to being fed to the third arrangement 13 are fed to a seventh arrangement 17 which is arranged to evaluate according to a second predetermined algorithm (as will be explained) the accumulated discharge duration and the outputs of the sixth and seventh arrangements 16, 17, are fed to an eighth arrangement 18 which evaluates the remaining discharge duration available from the battery 9.
The algorithms which are used in the system 10 are formulated on the basis of the output fro
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IBM Technical Disclosure Bulletin, vol. 29, No. 1, Jun. 1986, pp. 352-356.
Opalport Electronics Limited
Tobin Chistopher M.
Wieder Kenneth A.
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