Performance evaluation, modeling, and application of Lithium Polymer Batteries in Electric Vehicles

The performance of 100 Ah lithium polymer battery cells was evaluated in the battery evaluation to determine their suitability for use in Electric Vehicles (EVs). The performance includes: battery cell capacity, battery cell efficiency, temperature effects on the performance of the battery cell, self discharge, fast chargeability, realistic load test, and life cycle. These are important factors that determine the battery's suitability for use in EVs. The characteristic tests are conducted at four different temperatures to study the effect of seasonal changes. It was found that the lithium polymer battery cells need a cooling in summer and heating in winter during charging, discharging, and driving the EV. The tests also show that the lithium battery cells performed well during the evaluation at 0°C, +20°C, and +40°C. Furthermore the tests show that the battery cells can be fast charged and the cell's voltage stayed with the limits during the realistic load test. Moreover the lithium battery cells exhibited very high energy efficiency, low self discharge rate, and long life cycle.;A circuit model for a 100Ah Lithium Polymer cell that takes into account the effect of temperature and discharge rate was developed. This was done by studying the behavior of four advanced 100 Ah Lithium Polymer Battery cells under different load conditions and at different temperatures to extract the RC parameters needed to develop the equivalent circuit model. It presents a methodology to identify the several parameters of the model. The parameters of the circuit model depend on both battery cell temperature and discharging current rate. The model is validated by comparing simulation results with experimental data collected during battery cell tests. The simulation results of the battery cell model are obtained using MATLAB program, and the experimental data were collected through the battery test system at the Battery Evaluation Lab at the University of Massachusetts, Lowell (UMass Lowell). This model is useful for optimization of the battery management system which is needed to run a battery bank safely in an electric car.;The lithium polymer battery cells were installed in one of the EVs with the Battery Management System (BMS) that was developed by Dr. Frank Tredeau to prevent the cells from catching fire if they were overcharged. Two Data Acquisition (DAQ) systems designed to record data during the charging, discharging, and test driving. The recorded data include: batteries voltage, charging and discharging current, battery and heatsink temperatures, shunt current, charged and discharged Ah, and State of Charge (SOC). The EV was driven and tested many times by Professor Salameh and the author. The data was analyzed and the performance was compared with other types of the EV batteries. The range for one charge was found at various ambient temperatures. The BMS revealed a weak cell that was replaced. After that, the car achieved more than 100 miles range on one charge and high energy density. The EV is still in service (driven by Professor Salameh) and it is working well.