SIRT posted:Super caps last a life time and don't fail like just like LED's vs. lamps. They are not like the old conventional caps which swell and fail due to cycle, age and heat.
That would be a false statement. Don't fool yourself into thinking that wet electrolytic capacitors of any type can even come close to the MTBF of LED components!
Here's one convenient calculator: Capacitor Life Calculators
From that page, here's a basic description of the life factors.
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.
Using their SuperCap model, I calculated some MTBF numbers. The Load Life rating, max temp, and rated voltage is for an actual supercap. Notice how a 10 degree rise in the ambient cut the MTBF in half. Also, MTBF is an average, not a minimum. You'll experience failures well below that number as well as well above, remember the statistical bell curve.
Values underlined are my entries. 40C is a pretty close estimation of the temperature in normal operation, the 50C is for illustrating the effects of temperature.
