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I am connecting a 3V power supply (CR2032/CR2450 coin cell) to a 1.5F 5.5V rated supercap. Given that the supply voltage is lesser than rated voltage of supercap, chances of any damage become minimal. But my doubt is: whether this setup would increase the quiescent current drawn by supercap and hence decrease the battery capacity.

Theoretically, i suspect it shouldn't make any difference but in a test circuit I observed quiescent current was higher than what was provided in supercap datasheet (when battery and supercap had reached the same voltage).

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  • \$\begingroup\$ What are your actual numbers? \$\endgroup\$
    – pipe
    May 22, 2020 at 13:56
  • \$\begingroup\$ 6uA is what datasheet specifies as quiescent current, i am observing around 200uA, although there's a possibility which i am considering is that my current measurement instrument might be faulty. But speaking purely theoretically, should this happen? \$\endgroup\$
    – mosdkr
    May 22, 2020 at 13:59
  • \$\begingroup\$ Link to data sheet please. \$\endgroup\$
    – Andy aka
    May 22, 2020 at 14:00
  • \$\begingroup\$ Datasheet : mouser.in/datasheet/2/212/1/KEM_S6019_FE-1103433.pdf \$\endgroup\$
    – mosdkr
    May 22, 2020 at 14:10
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    \$\begingroup\$ @mosdkr in that replacement data sheet it is a 6 volt part and not the 5.5 volt part originally in your question. So, what page does it say 6 uA? Please don't point me to other questions, when this is still active - where is the 6 uA stated? What page? \$\endgroup\$
    – Andy aka
    May 24, 2020 at 10:55

1 Answer 1

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Make sure you've let the capacitor soak for the time mentioned on the datasheet or application data. For example, AVX specifies the leakage as 10uA after 72 hours.

enter image description here

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  • \$\begingroup\$ thanks a lot, this can be the issue, the values I quoted in the question are taken at around 1 hour. In that case can you confirm that afters 72 hours I should observe similar values as per the datasheet and "supply voltage<rated voltage" should not be an issue \$\endgroup\$
    – mosdkr
    May 22, 2020 at 14:13
  • \$\begingroup\$ Yes, that is correct. \$\endgroup\$ May 22, 2020 at 14:14
  • \$\begingroup\$ thank you very much \$\endgroup\$
    – mosdkr
    May 22, 2020 at 14:14
  • \$\begingroup\$ However, given the datasheet you linked, the datasheet specification seems to be <2.3mA after 30 minutes. Where is the 6uA stated? \$\endgroup\$ May 22, 2020 at 14:24
  • \$\begingroup\$ Hi Spehro can you please see if you can help me with this : electronics.stackexchange.com/q/501616/253198 \$\endgroup\$
    – mosdkr
    May 24, 2020 at 9:46

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