The analysis of Li-ion battery pack 48V 15Ah performance for electric bike

Abstract

The main problems related to the E-Bike battery mostly appeared from the limited output power, due to the battery chemistry, the dimension, or the capacities. The output voltages from 12V until 48V of batteries are commonly used as the main supply. Aim of this paper was to design and built lithium-ion battery pack with the lightest and higher performance by applying 21700 NMC Cells. were designed and constructed. This battery pack will be placed in E-bike to power the 500W BLDC Motor. The output voltages of 48V, and the capacities of 15Ah were built from 39 cells of 21700 NMC, with configurations of 13 series and 3 parallels. In addition, the BMS was connected for protection and cell balancing features. The performance of the battery pack was analyzed using a Battery Testing Analyzer. The parameter of this study were the cell and pack charge-discharge capacity, C-rate dependence, and High C-rate capability. The output power from the battery is also measured in the dynamic condition while the motor running at a different speed. The results showed that the 21700 NMC 5000 mAh cell has a capacity of 4615.74 mAh (after 50 cycles) with 0.5C current. The 48V 15Ah battery pack delivered charge capacities of 13.28 Ah (1C), 13.70 Ah (0.3C), 13.61 Ah (0.5C), and a discharge capacity of 13.21 Ah (1C). It was capable of delivering the higher current up to 15 Amps (1C) during charge and discharge. At higher C-rates the amount of capacity inside the battery decreased, cell temperature increased, and the driving time of the E-Bike also could decrease. The NMC cells are capable of delivering higher C-rate performance to achieve high power and torque.