A Life Prediction Of Ni-MH Batteries For Hybird Electric Vehicle

Since energy and environment problems become increasingly serious, energy conserving and environment friendly cars with low emissions have drawn a great deal of attention all over zhe world. High erergy battery pack , as the power source, is one of the key components of the electric vehicles. Some characteristics of battery , such as specific energy, specific power, cycle life, have fatal affects on the performance of HEV.At the moment, there are many kinds of batteries in the market. But Ni-MH battery power depend on high specific energy, high specific power, long cycle life, small environmental pollution, high safety and other advantages to be widely applied for HEV. So that is very important to test the battery performances. Through testing the characters of battery in the different environment, we can obtain that differernt variables produce different affect on battery, On this basis, the battery life can be predicted. The main content of this article can be divided into the following several aspects:â‘ The battery chemistry principle,develotpment situation and battery capacity factors have been introduced. Some parameters which can reflect the barrery capacity are proposed., and combining battery charging and discharging of cycling tests, it indicates that all parameters with the increasing of cycle showed different conditions, which provides a new method for the judgment of battery capacity attenuation.â‘¡Temperature and currents are the main factor which affect the capacity attenuation of the battery charging and discharging. Through the charging and discharging test in different environment temperature,charging mafnification and dischargr ratio, the result that the different trends of battery capacity and voltage and the different degree of damage has been showed. Based on the battery charging and discharging efficiency and battery minimum damage degree, optimum temperature and battery charge and discharge current range are put forward to improve the battery circle life.â‘¢Based on the theory of reflection model principle and Revised Arrhenius formula, a formula was established to forecast Ni-MH battery capacity arrenuation under a different temperature and currents based on the test data. According to the best work area of the current and temperature of the battery, the battery capacity attenuation curve will be showed through testing the battery characteristics in different conditions. Using the power function to fit capacity attenuation curve and fitting parameters by the experimental data, the ultimate expression is obtained at last. Then it is proved to be reasonable and correct by the experimental data.â‘£According to the simplify current that car manufacturer supplied, the battery capacity attenuation situation can be forecasted with the formula and damage accumulative principle. This formula has certain applicability by the contrast test resules and forecasting rusults. Though there are some errors, the results are consistent with the test value general trend.