100V rated caps @ 35V

[a.wayne]

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

 

[nigelwright7557]

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]

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]

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

 

[a.wayne]

Thanks for the response guys ...

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 ...?

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]

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]

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]

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).