An adaptive battery monitoring system for an electric vehicle

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 to predict when the batteries need replacing. This paper describes a battery monitoring system that is able to calculate the state of charge and state of health of multiple 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 noload conditions.