Effect of continously charging on supercapacitor

Discussion in 'General Electronics Chat' started by ttf, Jun 9, 2015.

  1. ttf

    Thread Starter New Member

    Mar 11, 2015
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    Hi, I am charging a supercapacitor continuously using a power source while connecting to a load. Will this affect the life time of the supercapacitor? If yes, why and what's the impact? I did some searching on the forum and internet resources but could not find a satisfactory answer. Hence, kindly advise if you know the answer, and point me to the relevant materials. Thank you.
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    as long as the charge source does not increase the voltage above the upper limit(2.5 V for example) then it should cause no harm to the cap. Consult the data sheet for max. voltage limit information.
    otherwise it will behave like a battery in similar use.
     
  3. ian field

    Distinguished Member

    Oct 27, 2012
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    Ditto: they're fairly strict about their low voltage capability, but the little tiny ones for memory backup in VCRs etc are fed from the supply the whole time the appliance has supply.
     
  4. ttf

    Thread Starter New Member

    Mar 11, 2015
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    Noted. Thank you!
     
  5. wayneh

    Expert

    Sep 9, 2010
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    I agree if we are talking about a mostly DC system. But if there is significant AC involved, then you need to consider the current and power ratings. A high frequency AC could roast it, if it's not rated for that.
     
  6. ttf

    Thread Starter New Member

    Mar 11, 2015
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    To protect from over-voltage, I can use a zener diode as a shunt regulator. Is there a better solution? If yes, please advise. Thank you.
     
  7. ian field

    Distinguished Member

    Oct 27, 2012
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    Zeners have a small amount of dynamic resistance, but at the low current you'd soak a supercap it shouldn't be that big a problem. You could feed the zener without the cap with the current limiting resistor you intend to use and check the voltage doesn't go over.

    The TL431 programmable zener has a pretty sharp knee curve - but you'd have to put the programming resistors across the cap, which would sort of defeat the object.

    Another option is a string of forward biased junctions, individually the knee is a little sharper than a zener, but they add together - so its win some, lose some.
     
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