FTUI Doctor Examines Battery State of Charge Calculations

The use of batteries as storage for energy supply is now increasingly important, considering the increasingly widespread use of devices driven by battery power. The use of batteries in these devices is not only limited to simple or complex applications and uses large loads such as UPS in the industrial world, telecommunications systems, mobile systems ; but it is also used in applications as a renewable energy storage, ranging from cell phones, laptop computers to lighting.

Battery State of Charge (SoC) is a parameter used to determine the state of battery charge and is used as a guideline for monitoring the current capacity of the battery. Estimating the SoC value becomes difficult because of the nonlinearity in the chemical reaction of the battery plus SoC cannot be measured directly. SoC can be obtained through the value of the internal resistance of the battery which is correlated with the magnitude of the terminal voltage and the open circuit voltage that occurs due to current both during the charging and discharging process.

This problem caught the attention of Mohammad Iwan Wahyuddin and outlined in his dissertation entitled, “Estimation of the State of Charge of Lead Acid Batteries Based on the Modified Coulomb Counting Method Using Internal Resistance Parameters and Recovery Effects.” This dissertation was presented at the Doctoral Promotion Session of the Department of Electrical Engineering, Faculty of Engineering, Universitas Indonesia which was held on Tuesday (27/12).

“Modification of the coulomb counting method in obtaining internal resistance values ​​is easily carried out through the equation approach obtained through interpolation of experimental data. This method succeeded in obtaining a correlation between the SoC value and the internal resistance for two conditions, namely charging and discharging. The process of estimating the SoC value is done by estimating the initial SoC value when the recovery effect occurs to obtain the maximum/minimum value for a certain period. The method developed succeeded in estimating the SoC value of the battery by indirectly measuring the resistance in the battery during the charging or discharging process,” explained Iwan in his presentation.

Dean of FTUI, Prof. Dr. Heri Hermansyah, ST., M.Eng. revealed, “The problem of determining battery capacity in applications requires accurate monitoring and estimates. Accuracy is an important issue to maintain the reliability and safety of battery use. It is hoped that the results of Dr. M. Iwan Wahyuddin can provide an appropriate algorithm solution to overcome the problem of non-linear differences in battery parameters.”

Mohammad Iwan Wahyuddin won his Doctoral degree with the title of Very Satisfactory at the Doctoral Promotion Session. He is the 150th Doctor who graduated from the Department of Electrical Engineering and the 484th Doctorate at FTUI. The doctoral promotion session was chaired by the Chairman of the Session, Prof. Dr. Eng. Drs. Benyamin Kusumo Putro, M.Eng. with the Promoter, Prof. Dr. Ir. Harry Sudibyo S., DEA and Co-Promoter, Dr. Ir. Purnomo Sidi Priambodo, M.Sc. The Examiner Team consisted of Burhanuddin Halimi, S.T., M.T., Ph.D., Dr. Ir. Bambang Priyono, M.T., Dr. Ir. Feri Yusivar, M.Eng., Dr. Abdul Halim, M.Eng., and Tomu Abuzairi, S.T., M.Sc., Ph.D.


Bureau of Public Communications
Faculty of Engineering, Universitas Indonesia