Operating conditions directly affect the life of an aluminum electrolytic capacitor. The ambient temperature has the largest effect on life. The relationship between life and temperature follows a chemical reaction formula called Arrhenius' Law of Chemical Activity. Simply put, the law says that life of a capacitor doubles for every 10 degree Celsius decrease in temperature (within limits).
Voltage derating also increases the life of a capacitor, but to a far lesser extent, as compared to temperature deratings. Internal heating, caused by the applied ripple current, reduces the projected life of an aluminum electrolytic capacitor.
The relationship between capacitor life and the operating conditions can be calculated by the following equations:
The operating conditions affect the life of a film capacitor in a very similar manner to aluminum electrolytic capacitors. Voltage derating has a greater effect on the life as compared to an aluminum electrolytic capacitor. The life expectancy formula for film capacitors is expressed by the following equation:
The life of a ceramic capacitor at the operating conditions is expressed by the following equation: