State of charge (SoC) estimation on LiFePO<inf>4</inf> battery module using Coulomb counting methods with modified Peukert

Abstract

Batteries have an important role in the development of electrical energy utilization, such as in renewable energy and electric vehicles. Batteries with good performance would support the devices which utilized them. Because the amount of energy stored in a battery is limited, so battery getting charging and discharging cycles. Improper charge and discharge process could decrease the battery's performance. Therefore battery management system (BMS) is very necessary so that could maintain performance of the battery at optimum condition. One of the important aspect in BMS is state of charge (SoC), which indicate the amount of energy left in the battery. In this work, SOC estimation calculated using Coulomb Counting method which is calculate and compare the electric charge that came in and came out the battery. Upon Coulomb counting on discharging and charging process, battery's SoC estimated by different ways, namely calculate the Peukert's effect and calculate charging efficiency, respectively. Modified Peukert relationship includes current rate parameters are affecting discharge capacity of a battery. Higher Peukert constant would lead to decreasing of operational battery module voltages. Moreover, it could be studied that Peukert only has an effect in the changes of discharge capacity at zero point of SoC. Furthermore, from experimental result it has been known that energy stored in the battery might be has different deep of discharge depends on Peukert constant.