100V rated caps @ 35V

a.wayne · 16th September 2011, 09:20 PM

Any thoughts on running 100v rated caps @ 35 volts in a PSU, any negatives attached to doing so ...?

nigelwright7557 · 16th September 2011, 09:31 PM

Quote:

Originally Posted by a.wayne

Any thoughts on running 100v rated caps @ 35 volts in a PSU, any negatives attached to doing so ...?

As long as ESR and value are the same shouldnt make a difference.

marce · 17th September 2011, 11:36 AM

Yes, caps are better if de-rated by 50%, when MTBF figures are calculated you have to de-rate them by at least 50% to get a decent result.

RJM1 · 17th September 2011, 01:17 PM

As long as they fit, also see the previous two posts.

a.wayne · 18th September 2011, 04:46 AM

Thanks for the response guys ...

Quote:

Originally Posted by marce

Yes, caps are better if de-rated by 50%, when MTBF figures are calculated you have to de-rate them by at least 50% to get a decent result.

De-rate

are you saying view the 100 v cap as a 50 V ...?

Quote:

Originally Posted by nigelwright7557

As long as ESR and value are the same shouldnt make a difference.

Well, I have some 50v caps that i just might end up using instead of the 100v units, they have lower esr's ..

marce · 20th September 2011, 11:47 AM

Yes, if you can afford the higher voltage rating, dont forget also the occasional spike etc can hit equipement. The 50V cap will also work. When any high reliabilty products are designed, electroyiticas are always de-rated 50%, otherwise you dont get the required MTBF figures.

DF96 · 20th September 2011, 01:09 PM

If you run 100V electrolytics at 35V for many years they can become, in effect, 35V caps. Fine while in situ. Problems can come if you re-use them for another project where they have much higher voltage across them. You would first have to re-form them back up to a higher voltage.

Ron AKA · 20th September 2011, 11:53 PM

Check out the new Panasonic FR series caps. They only go up to 50 V but have some pretty impressive ESR values, life (10,000 hrs), and capacitance for a given size. But, to your question no harm in using over voltage rated caps. Often you can get more ripple current capacity and ESR for a given capacitance (but at a price in capacitor physical size).

16th September 2011, 09:20 PM	#1
a.wayne diyAudio Member Join Date: May 2008 Location: Front Row Center	100V rated caps @ 35V Any thoughts on running 100v rated caps @ 35 volts in a PSU, any negatives attached to doing so ...?

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17th September 2011, 11:36 AM	#3
marce diyAudio Member Join Date: Jun 2007 Location: Blackburn, Lancs	Yes, caps are better if de-rated by 50%, when MTBF figures are calculated you have to de-rate them by at least 50% to get a decent result.

17th September 2011, 01:17 PM	#4
RJM1 diyAudio Member Join Date: Jan 2010 Location: Titusville, Fl.	As long as they fit, also see the previous two posts.

20th September 2011, 11:47 AM	#6
marce diyAudio Member Join Date: Jun 2007 Location: Blackburn, Lancs	Yes, if you can afford the higher voltage rating, dont forget also the occasional spike etc can hit equipement. The 50V cap will also work. When any high reliabilty products are designed, electroyiticas are always de-rated 50%, otherwise you dont get the required MTBF figures.

20th September 2011, 01:09 PM	#7
DF96 diyAudio Member Join Date: May 2007	If you run 100V electrolytics at 35V for many years they can become, in effect, 35V caps. Fine while in situ. Problems can come if you re-use them for another project where they have much higher voltage across them. You would first have to re-form them back up to a higher voltage.

20th September 2011, 11:53 PM	#8
Ron AKA diyAudio Member Join Date: Aug 2011	Check out the new Panasonic FR series caps. They only go up to 50 V but have some pretty impressive ESR values, life (10,000 hrs), and capacitance for a given size. But, to your question no harm in using over voltage rated caps. Often you can get more ripple current capacity and ESR for a given capacitance (but at a price in capacitor physical size).

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