An adaptive battery monitoring system for an electric vehicle.
Thesis DisciplineElectrical Engineering
Degree GrantorUniversity of Canterbury
Degree NameMaster of Engineering
In electric vehicles it is important to know the state of charge of the batteries in order to prevent vehicle strandings and to ensure that the full range of the vehicle is exploited. It is 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 also identify batteries that are not performing optimally within the battery bank. This thesis describes a battery monitoring system that is able to calculate the state of charge and state of health of niultiple batteries in a battery bank, It has been designed specifically to monitor lead-acid batteries in an electric car environment using noninvasive measurement techniques. The monitor incorporates an adaptive monitoring method, which is based on coulometric measurements when the batteries are under load and predicted open circuit voltage measurements under no-load conditions. The battery monitor is micro controller based and uses remote battery monitoring modules to make the necessary battery measurements. Information is presented to the user of the car in the form of a state of charge meter on the instrument panel, similar to a fuel gauge in a conventionally power vehicle, and an alphanumeric LCn panel on the car's dashboard. . Aspects of both the monitor hardware and software are considered in this thesis. Results obtained from bench tests of the monitor are presented which are followed by an evaluation of the monitor's performance. Consideration is also given to possible future improvements to the monitoring system.