In electric vehicles it is important to know the state of charge of the batteries in order toprevent vehicle strandings and to ensure that the full range of the vehicle is exploited. Itis also useful to know state of health information about the batteries in the battery bank,This information can be used to predict when the batteries need replacing and can alsoidentify batteries that are not performing optimally within the battery bank.This thesis describes a battery monitoring system that is able to calculate the state ofcharge and state of health of niultiple batteries in a battery bank, It has been designedspecifically to monitor lead-acid batteries in an electric car environment usingnoninvasive measurement techniques. The monitor incorporates an adaptive monitoringmethod, which is based on coulometric measurements when the batteries are under loadand predicted open circuit voltage measurements under no-load conditions.The battery monitor is micro controller based and uses remote battery monitoring modulesto make the necessary battery measurements. Information is presented to the user of thecar in the form of a state of charge meter on the instrument panel, similar to a fuel gaugein a conventionally power vehicle, and an alphanumeric LCn panel on the car'sdashboard. . Aspects of both the monitor hardware and software are considered in thisthesis.Results obtained from bench tests of the monitor are presented which are followed by anevaluation of the monitor's performance. Consideration is also given to possible futureimprovements to the monitoring system.
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