EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: BrainyCapacitance on April 18, 2024, 01:01:51 am
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err... I need help. I bought these 10F 3V supercaps made by Cornell Dubilier off Mouser. on my first time testing one, my circuit shorted out. I checked the circuit, but nothing was wrong. the circuit is supplying 2.3v, at 1.5a max. and the supercap polarity was correct. so I checked that supercap with my meter on a 2v conductivity test. it gave me the "short circuit" signal. and then, I ran it through resistance mode, and it shows the resistance between the supercap's + and - is 10Ω. yep. 10Ω. so I thought maybe that specific capacitor was faulty. I grabbed another supercap and conductivity then resistance. same thing. but I think, since these are all-new and haven't been used before, maybe it's just a "sleepy dielectric" :=\. what do you think? if it is a "sleepy dielectric", how can I "wake up" the dielectric without frying my MOSFET or voltage reg? plz be gentle :-\
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Your ohmmeter is going to take a very LONG time to charge up a 10F super capacitor... During that time, its going to read as a very low resistance if it started out fully discharged.
Charge it via a resistor to limit the current. Or use a power supply with current limiting that can handle a continuous short.
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You can use a 3V incandescent bulb to limit the current when charging and provide an indication of the charging progress.
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So do you expect it charging in milliseconds? If circuit has no charging current limit, supercapacitor will basically cause a short circuit.
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that "circuit" wasn't my ohmeter
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what do you mean "has no current limit"
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what do you mean "has no current limit"
It means you connect it directly to constant voltage power supply. If it's a switch mode supply, most likely it will just go into protection, try restarting, go into protection again.
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charging a supercap can take a very long time, in some case it will appear as a dead short
i usually use them in clock related stuff or clock backed up mcu etc ... i use an resistor to drop the inrush it create, sure it create a time constant, a simple diode and a resistor on the clock ic ....
for an 1.5 farad at 5v it take at least 15 mins to charge it, and keep 1 week of clock
10 farad is a lot ... i mean a lot loll
for sure you don't use that to filter out an psu ??
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BTW, here is the schematic of "the circuit" that shorted out because of the sleepy Supercap:
I am just a starter at electronics, so please tell me if this circuit is bad gently
[attachimg=1]
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use a power supply with current limiting that can handle a continuous short.
okay, so something like This?
[attachimg=1]
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Both circuits are totally nonsensical. No surprise it doesn't work.
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Just FYI, the OP is a 16 year old.
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BTW, here is the schematic of "the circuit" that shorted out because of the sleepy Supercap:
I am just a starter at electronics, so please tell me if this circuit is bad gently
What do you want the circuit to do? The easiest way to charge your supercap is to use a voltage supply and then a series resistor to limit the current. For a supply putting out 2.3V, a 10-ohm resistor would limit the current to 230mA maximum. Your supercap will take a bit of time to charge.
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You got parts delivered to Antarctica from Mouser?? It's a pain in the ass to get them to Iceland! When first applying a voltage to any capacitor it will appear as a dead short if it is in an energy storage type circuit. You have to current limit the charge with a simple resistor.
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err... I'm not ACTUALLY in Antarctica. I just chose it for "safety reasons". I hope you can understand