Hello guys, I have a DIY project with an ESP32 and a SIM800-module.
The SIM800-module requires a 470uF, 10V cap to be placed across GND and VCC to provide enough current.
However, I've estimated that this little cap draws around 100mAh energy each day, which makes it not ideal for low-power projects.
Can you recommend different caps with high discharge times please?
Buy a new cap! Have you actually measured the leakage?
How did you work this out? Good quality, working, not faulty capacitors do no leak that much.
Surprisingly very few people cares about capacitor leakage. What I have found datasheets specifications are overestimated by many orders of magnitude in typical situation. The sources I have found claim the leakage increases with increasing temperature and supply voltage. I guess it is also worse with a ripple current. But it is very very low at reasonable voltage and room temperature. Also in some (short) time the aluminium caps self-heal by the leakage current: it is quite large at first but drops quickly (in minutes) no near zero value.
Example: for the test of the leakage I have a 6300 uF 6V3 cap powered from two new AA alkaline batteries (about 3V) after a day the leakage dropped to ~2nA (measured by a DMM in voltage mode: it has internal resistance of 10 MOhm and measures about 20mV voltage drop) and stays on this value for about a week.
Surprisingly very few people cares about capacitor leakage.
Probably because we know that for a good capacitor it's low enough not to matter, and for a bad capacitor it also doesn't matter because a bad capacitor will be replaced with a good one.
++Karma; // For a very informative post.