Capacitor Replacement

If you found an e-cap bad and could not locate the same exact value, usually you will look up for a replacement that have higher voltage-am i right? For example, you replace a 470uf 25 volt with a 470uf 35 volt capacitor. The question now is could you replace the e-cap say with 470uf 150 volt? The answer is for electrolytics, the operating voltage should not exceed by about 50 % the working voltage of the original cap, or the circuit voltage. An e-cap with a much higher voltage rating may, over time, decrease its amount of capacitance when operated on a considerably lower voltage. Technically, the capacitor cannot properly form itself at the lower voltage , and loses capacity and this cap will give you problem down the road.

13 Comments

1. 

   Waleed

   August 18, 2010 at 4:39 pm

   is that a proven fact? let me know please

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2. 

   beh

   August 19, 2010 at 4:07 am

   HI JESTINE

   i experinced this i put e -cap with higher voltage value in the circuite.
   yes . not work ed . i t was on the b+ voltage circuite of a monitor
   thanks for good answer
   beh

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3. 

   admin

   August 19, 2010 at 6:38 am

   Hi Waleed,

   Yes it was proven and again proven by Mr Beh in his comment.

   Jestine

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4. 

   Sam C

   August 19, 2010 at 10:28 am

   Thanks for the tip. I didn't know the 50% working voltage rule. Does that apply to solid state polymer capacitors ?
   High end motherboard maker Abit boasts that they use solid state capacitors that last up to 6.25 times than aluminum caps.
   http://www.abit.com.tw/page/au/motherboard/motherboard_detail.php?pMODEL_NAME=IP35+Pro&fMTYPE=LGA775

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5. 

   Waleed

   August 19, 2010 at 2:49 pm

   thanks for a new lesson today. God bless

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6. 

   admin

   August 19, 2010 at 7:44 pm

   HI Sam,

   Thanks for the link and the information. I have not tested on the solid state polymer caps thus i can't provide any answer on this matter.

   Jestine

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7. 

   hartono

   August 19, 2010 at 10:22 pm

   That is not the case, because the higher the operating voltage, the esr will increase too. If the esr is not the limiting value, I think changing e-cap with higher voltage will prolong the life of it. It will be less stress to the e-cap itself.

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8. 

   beh

   August 21, 2010 at 4:03 am

   HI WALEED

   yes this is true i really do not have any electronical explanation for this.
   john you have any answer to this?
   thnx
   beh

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9. 

   admin

   August 23, 2010 at 4:44 am

   Hi Hartono,

   Thanks for your comment. I guess finding e-caps for replacement is not a problem because it is so easily available from the market. Getting a bigger volt cap means we have to pay more and the physical size also does not really permit us to put it back to the original location unless we do some modification which can take up our time.

   Jestine

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10. 

    Dave

    December 7, 2010 at 11:10 am

    Can I replace a 10v 3300uf with a 6.3v 3300uf? This is the only capacitor I can find locally with the same uf rating. If not, can you explain the reason?

    Thanks,

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11. 

    admin

    December 7, 2010 at 8:59 pm

    Hi Dave,

    For a 10 volt cap, usually the voltage across the cap is bigger than the 6.3 volt thus it will blow the 6.3 volt cap.

    Jestine

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12. 

    nuh adamu

    January 1, 2014 at 10:26 pm

    Thank u jestine & co for your unrelenting contributions all year round.

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    • 

      Jestine Yong

      January 2, 2014 at 10:48 am

      HI Nuh,

      You are welcome!

      Jestine

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