  Battery pack used in electrical vehicles (EVs) have developed fastly nowadays
and are important due to its capability to stores electric charge. However, it
is still found that there is an electrical voltage fluctuations due to sudden
load changes or faults in the power system. To overcome this problem, the
conventional strategy focuses on using voltage stabilizer with
inductor-capacitor resonant circuits, leaving the problem of using capacitors
at cryogenic temperatures. Herewith, we design a vehicle automatic voltage
stabilizer (VAVS) operating at room temperature. The VAVS consists of nine main
components, including resistors, capacitors, transistors, and diodes arranged
with a specific composition to stabilize the voltage. By considering Al
electrolytic capacitor, type of diode, resistor, and transistor, the VAVS
device stabilizes the input voltage from 10-15V to obtain an output voltage of
12V. Then, by varying the engine rotation speed of vehicle, VAVS applied in
vehicle battery supplies a constant voltage of about 12.1 V. The lowest line
regulation analysis reveals a regulated voltage fluctuation of 0.17%/V. Our
result shows that VAVS design works at room temperature, overcomes the voltage
fluctuation and complies with the standard regulation of voltage stabilizers.
