A study on effective thermal-shock test improvement of battery packs for PHEVs

While there are many test items to secure a vehicle's reliability, this study reviews the test method for Thermal-shock Test, one of climatic tests to evaluate the damage caused by thermal expansion coefficient differences of parts by rapid temperature change, and proposes more appropriate test method for test performance evaluation. The testing for automobile electronic parts is divided into two categories for reliability and for stability, and is varied in wide range. In this study, Thermal-shock Test, which performed to acquire durability life, one of the important factors of the automobile electronic part tests, is analyzed. The current Thermal-shock Test is conducted with higher than 500 cycles in case of automobile interior electronic parts, or higher than 1,000 cycles in case of the parts in the engine room or of the exterior or special area of automobile. And, according to installation area, the tests are performed in high temperature (75-115°C) and in low temperature (-40°C). And, test profile time is to evaluate battery's performance reduction by changing temperature for total one hour (high temperature, 30 min and low temperature 30 min). During and after the evaluation, any abnormality, such as venting, battery enclosure rupture, fire, or explosion, shouldn't be occurred to the tested battery. Also, the internal resistance should satisfy the preset range. Therefore, with Thermal-shock Standard Test, the Battery Pack for PHEV in development process is to be evaluated. And, the evaluation result is analyzed to verify if the evaluation can be performed with trust as the evaluation to other automobile electronic parts followed by a proposal of detailed test measure. Firstly the internal structure of the developed battery pack for PHEV is analyzed. Then, through the test method recently applied, the test procedure to measure the temperature distribution of battery pack is to be established. And, by analyzing the international thermal-shock test standard and conducting the test on the proposed profile, the detailed test method is drawn. After the verification process for the proposed test method, the reliability is to be secured.