# Can I apply a voltage higher than a capacitor's rated voltage

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#### stephenkohnle53

I have a 5.5v .22F capacitor and I plan on using a 6v led on it for a project. Since I am not going to need to use it much and I am willing to do minor damage to the capacitor could I do that. By the way its for a school project so I will likely use it once or twice then keep it but never use it again.

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#### JRMichler

When an electrical component is run at exactly its rated voltage, it will have a certain MTBF (Mean Time Between Failures). The MTBF decreases quickly as the voltage increases. At some voltage, it arcs over / fails / explodes / melts immediately. You will probably have no problems putting 6 volts on a 5.5 volt capacitor if you only do it once or twice. Any damage, however, will not be minor. The capacitor will either still be good, or it will be destroyed.

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#### stephenkohnle53

Alright that is what I thought would happen, I think I will see how bright the led is, at say 5v and if it is bright enough then I will use that, otherwise I will use 6v. I got the capacitor from salvaged electronics so I can always get a new one if it gets damaged.

#### Borek

Mentor
Typically connecting a LED to 5.5 V (or 6 V) is an almost sure way of killing it.

You need to protect the LED from too high current.

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#### stephenkohnle53

I was planning on adding a 220 ohm resistor. I did not calculate the ohms needed, I read that, that is a good resistor for it. I made a thread about the project here https://www.physicsforums.com/threads/how-to-wire-an-emergency-flashlight.934421/#post-5902730

I put this as a separate thread so others can see this for other projects instead of getting the information from a thread devoted to a flashlight rather than whatever someone else might be searching for. If you want to discuss the resistance needed please go to the other thread as for other protections needed feel free to put that here or the other thread

#### Borek

Mentor
Yes, with 220 Ω it should be OK, you have just not mentioned the other info earlier.

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#### stephenkohnle53

Yeah, I have been up far later than I should disassembling things, so I am a little forgetful. Any way after school I will gather some switches then post the supplies I have scavenged in the other thread.

#### the_emi_guy

What is the function of this capacitor?

If it is a ceramic capacitor, the likely effect will be that it will have only a fraction of its nominal 0.22uf of capacitance.

#### Borek

Mentor
My bet is that OP means not 0.22μF but 0.22F supercapacitor.

#### the_emi_guy

My bet is that OP means not 0.22μF but 0.22F supercapacitor.
Thanks,
Didn't notice that...

#### sophiecentaur

Gold Member
Why not just run the LED on 5.5V? It will stay alight at a much lower voltage than that.
Remember that, if you plan to use a Capacitor as a power source, its voltage will start to drop as soon as you connect the LED. (Unlike a 6V battery)
What is the current drain of the LED?

"Can I apply a voltage higher than a capacitor's rated voltage"

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