This paper presents and evaluates the effect of charge/discharge rate on the supercapacitorpsilas temperature. Experiments show that during charging the temperature rises more than during discharging. The paper also investigates the supercapacitorpsilas energy efficiency as a function of the discharge time and the level of the voltage discharge ratio. Where the voltage discharge ratio is defined as the ratio between the minimum allowed voltage at certain discharge time and the maximum voltage at fully charged. It was found out that the lower the discharge time, the lower the efficiency. Moreover a mathematical model for the efficiency as a function of discharge time was developed and verified experimentally.