Will I Be OK Using 50V Nichicons in my 9V Stompbox?

[turunturun]

So the lowest voltage radial caps I could find in the 1uF value were 50V. I bought them before researching that you shouldn't go to far over-spec on electrolytic cap voltage. It seems the rule of thumb is something like 50% or less actual voltage versus spec compromises the life-span of within value operation.
So for a 9V pedal 50V caps will be running pretty seriously under spec (18%), but others have said that 25V are fine and that would only be about 36% spec'd voltage in a 9V pedal. (BTW the pedal in question is the Christine Fuzz from musicpcb.com)

Whats up?

(thanks)

[Kearns892]

The 50v Cap should be fine. Electrolytic caps will always go bad over time. Using the 50v cap significantly under spec may speed up this process, but it should still work fine.

[Fender3D]

...Using the 50v cap significantly under spec may speed up this process...

Why would it ever occour?
50V should be the max allowed voltage, if you supply a lower voltage why would it hurt them?

Use those caps and don't worry unless you'll hook more than 5 batteries... 

[Kearns892]

...Using the 50v cap significantly under spec may speed up this process...

Why would it ever occour?
50V should be the max allowed voltage, if you supply a lower voltage why would it hurt them?

Use those caps and don't worry unless you'll hook more than 5 batteries... 

I has never heard that either. I was referring to what turunturun has mentioned. I also saw something around here earlier about electros possibly going dead quicker if they are not used. I honestly don't know how they break down - that is a question for someone else - I do know though, that they should be fine for stompbox purposes.

[defaced]

Use the caps, they'll be fine.

This is from United Chemi-Con.  I do not see "under voltage" as a cause of failure.  I do see "normal wear" as one though.  Electros will die.  You can not avoid it.  It's just one of those things where you accept it for what it is and replace them when they need it.  Probably in 10 to 30 years.  http://www.chemi-con.com/u7002/table2.pdf

And another from Panasonic.  http://industrial.panasonic.com/www-data/pdf/ABA0000/ABA0000TE4.pdf

And more fun from Cornell Dubilier on application, which also discusses manufacturing of these things.  http://electrochem.cwru.edu/encycl/misc/c04-appguide.pdf

There's more on Google if you search "electrolytic capacitor failure modes". 

[thetragichero]

The 50v Cap should be fine. Electrolytic caps will always go bad over time. Using the 50v cap significantly under spec may speed up this process, but it should still work fine.

actually shouldn't it slow down the process?

[amptramp]

Turn to page 10-24 of this document:

http://www.goes-r.gov/procurement/flight_documents/MIL-HDBK-217F.pdf

and you will see that failure rate goes up with one term being the cube of the ratio of applied voltage to operating voltage.  Thus, operating a 50 volt capacitor at nine volts is better than operating it at any higher voltage.  MIL-HDBK-217F should be required reading for anyone designing or modifying electronics.  You can download thousands of man-hours of research at this link and get definitive answers.

The idea that electrolytic capacitors have a problem when operated substantially below their ratings came from old (1930's) capacitors at the beginning of the electrolytic era when a 10 µf 300 volt cap would become a 20 µF 150 volt cap if operated at 150 volts.  This was due to the poor anodizing processes that existed then.  Modern capacitors don't do this.