Some ESC questions for the Nerds!

[jsr]

I have a question regarding the input capacitor voltage ratings. Why is the voltage of the input caps typically ~10V above the highest supported input voltage rating?

Ex:
4s 14.8V rated ESC = Caps rated to 25V
6s 22.2V rated ESC = Caps rated to 35V

Typically in other circuits, the input filter cap voltage chosen isn't much higher than the supply voltage as the source shouldn't be able to supply more than the maximum rating. Even at full charge of 4.2V/cell, a 4s pack will only be able to supply 16.8V, no where near the 25V rating of the caps.

Thanks.