英文摘要 |
This is the second part of the work for the ISO 12405-1 tests for LiFePO_4 battery packs for Electric Vehicles (EV). Based on the test results from two individual battery packs in the first part, this paper reports on the effect of the surrounding temperature on the performances of two LiFePO_4 battery packs connected in series and in parallel during the charge / discharge process. In the ISO 12405-1 test, two constant charge rates 0.5C (10A) and 1C (20A) are used during the charge/discharge process to investigate LiFePO_4 battery performance. Performance measures include the voltage, current, capacity, energy and the battery pack surface ending temperature measurement. Since battery pack test data from batteries connected in series and in parallel during the charge / discharge processes using standard ISO 12405-1 tests are very rare in literature, one of the main contributions of this work is publishing the test data. The present results show that the high surrounding temperature increases the charge and discharge time, and the battery capacity and energy, which are attributed to the higher surrounding temperature, resulting in more favored internal battery chemical reaction. The internal resistance is consequently decreased, improving battery pack performance in the charge and discharge process. The durability and the portability of the EV battery pack, which depends on the energy dissipation per unit volume or weight, are important for EV battery manufacturing. To attain high performance, the top priority is battery pack design considering connection in series for accelerating and climbing, and connection in parallel for endurance by supplying the high battery energy and capacity. The test data can act as a reference to benefit EV battery manufacturing. |