Now I know when it comes to electrolytic capacitors it's usually good practice to use a voltage rating 1.5x - 2.5x the maximum rating you ever expect the capacitor to be exposed to, as the lifetime can be significantly reduced by running it near its limits.

But does the same protocol apply to ceramic capacitors? For example, assume a 25V ceramic capacitor - will running it at 24V reduce its lifespan significantly?

I'm currently designing a PSU which needs to be reliable, so at the moment I'm using 50V caps for a maximum 20V input (35V caps aren't available), but I'd like to switch to 25V caps if possible.


Question: Does anybody use an external battery for iPhone?
Answer: Yes - and most people I know fit into strongly preferring a rechargeable solution when they use the device regularly to extend power on the go.

Those that use the device occasionally or on long trips seem to gravitate to an inexpensive sled for AA batteries and carry a mix of expensive lithium cells and typical non-rechargeable cells.