Hybrid Method for State of Charge Estimation: An Experimental Study

New carbon emission laws are being implemented, countries support the use of renewable energy with decreasing the taxes for electric cars and energy production using solar. When we look toward the future this trend will grow everyday. For electric cars and renewable energy our best friend is batteries. On the otherhand if the batteries are not used properly they can cause significant damage. In order to use the battery efficiently and safely it is necessary to obtain the correct state of charge values, which varies depending on voltage, current and temperature. In this article, a system that can be adapted to electric vehicles using a modular battery management system and a charging unit, which allows user monitoring of cell information and uses a hybrid method to calculate the state of charge will be described. For this study, 2 different battery management boards and 1 charging board were designed, controlled experiments were carried out in a climate chamber and different charge-discharge profiles to establish the relationship between parameters such as temperature, open circuit voltage and charge-discharge current and state of charge. The results show that the method applied for SoC has a mean RMSE of 0.339 for charging and 0.255 for discharging, and is suitable for larger scale studies.