© 2020 AIAA.Using air vehicles for many purposes has been gaining great importance for decades. Therefore, reducing the flight gas emissions and providing a safe flight are crucial in our age. These attributes could be ensured by using the batteries in an air vehicle. However, they should be critically evaluated and sized at the design process of the electrical system to satisfy the international flight standards. In this paper, commonly used battery chemistries will be analyzed by using simulations and the temperature effect on the batteries in the flight mission will be assessed with different approaches. In the final part, a methodology will be recommended to analyze the impact of different ambient temperatures on emergency flight time.