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I have an energy harvesting application and I want to use a capacitor to store energy. Due to the application being very low power, a capacitor of around 50uF might be enough. What is really important though, is to have the lowest discharge possible, since the charging of the capacitor might be happening over a long period. What type of capacitor is best suited for this case?

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    \$\begingroup\$ I suggest that you have a look what is commonly used. Texas Instruments takes energy harvesting seriously so have a look at: ti.com/solution/other-energy-harvesting and see how they do it. \$\endgroup\$ – Bimpelrekkie Jun 9 at 12:24
  • \$\begingroup\$ Why not use a rechargeable battery to harvest the energy? \$\endgroup\$ – Leoman12 Jun 9 at 14:38
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You are looking for a capacitor with a high leakage resistance. A 50uF electrolytic capacitor is inexpensive and easy to find, but has a lower leakage resistance than other types of capacitors. You haven't mentioned the required voltage. That is an important consideration.

Here is a chart of capacitor technologies vs. leakage resistance:

Capasitor Technology vs. Leakage Resistance

The words "Values of" in the caption appear to be an error. The image is from page 8 of KEMET Corporation, Introduction to Capacitor Technologies Copyright 2013

Here is a chart showing the capacitance and voltage availability for several capacitor technologies. enter image description here

Image from: EPCI; ESA SPCD 2018 Symposium via https://epci.eu/capacitors-news-and-trends/

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  • \$\begingroup\$ A chart or additional information about voltages and capacitance values of each capacitor technology would complete the picture nicely. \$\endgroup\$ – NickG Jun 9 at 17:34
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    \$\begingroup\$ The document linked above has a similar chart showing "values of capacitors by dielectric." I will see what I can find about voltage ratings vs. capacitor type. \$\endgroup\$ – Charles Cowie Jun 9 at 21:05
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    \$\begingroup\$ Here is a site that has a lot of information about capacitors iequalscdvdt.com \$\endgroup\$ – Charles Cowie Jun 9 at 21:26

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