[TenTec] Electrolytic Capacitors

[Ken Brown]

This post is quite off topic. It only relates to Ten-Tec radio equipment 
vaguely, since there are electrolytic capacitors in them. I ask the 
question here, because I know there are knowledgeable people here who 
may be able to provide some insight.

Electrolytic capacitors require a voltage across them to maintain the 
oxide layer which is the dielectric between the plates, right? If they 
have no voltage across them for long periods, then they are likely to 
fail when full rated voltage is applied, right? What about an 
electrolytic capacitor which has a much higher voltage rating than that 
which appears across it in the circuit? Would the capacitor ESR increase 
over time until it fails, in an open (or real high ESR) mode? For 
instance what would you expect from a 25 VDC rated electrolytic 
capacitor which never has more than 5 volts applied to it?

Thanks in advance.

DE N6KB