In this thesis, the use of voltage, current and electrical power in Isuzu Panther 25 New Royale Year 2000 car was not stable, so a tool called capacitor bank was needed. Capacitor bank is a tool used to fix the quality of electrical energy supply that includes fixing the quality of the voltage on the load side, fixing power factor, and reducing loss of transmission. The data analysis of the research in the capacitor bank was divided into two. The first measurement was calculating total power of the vehicle without capacitor bank. The second was measuring total power of the vehicle using capacitor bank. Before the installment of capacitor bank, the amount of average electric voltage with the engine off was 9,3 V and when the engine was on, the amount of average electric voltage was 10,9 V. After the installment, there was an increase in the average voltage when the engine off was 11,3 V and when the engine was on, the amount of the average voltage was 12 V. It is concluded from the measurement result of charging system before installing the bank capacitor that the unstable electrical voltage and electric current from 13,1-14,5 V were caused by difference of engine speed and load usage. After the installment, capacitor bank became stable into 14,3-14,4 V.