How the heck do you charge a capacitor??

[95EXP4.0]

I have a capacitor a 5 farad cap 5.........i was told it's probably discharged from not being used. So how do I charge it back up, do I hook it up directly to the battery??

 

[rokke17]

Originally posted by 95EXP4.0
I have a capacitor a 5 farad cap 5.........i was told it's probably discharged from not being used. So how do I charge it back up, do I hook it up directly to the battery??

Connect the negative to the ground wire.
Then take the power wire that is connected to the battery and tap it repeatedly against the positive terminal on the cap to charge it.
You can also use the resisitor, but I am assuming if you are asking then you dont have the resistor.

Chris

 

[95EXP4.0]

I know it varies on the capacitor......but how long do I have to charge it?

 

[davesexplorer]

I charged my friends 1 farad with a resistor, it only took like 35-45 seconds

 

[rokke17]

Originally posted by davesexplorer
I charged my friends 1 farad with a resistor, it only took like 35-45 seconds

Sounds about right time wise.

Chris

 

[RFR2212]

Using a resistor is the correct way to do it. If ya connect the ground, and tap the positive wire to it, i dunno bout charging, but it probly will arc... from all my thinking, this isn't something I'd recommend

 

[95EXP4.0]

Ok, if I use the resistor what do I have to do and what type do I have to get?

 

[rokke17]

Originally posted by RFR2212
Using a resistor is the correct way to do it. If ya connect the ground, and tap the positive wire to it, i dunno bout charging, but it probly will arc... from all my thinking, this isn't something I'd recommend

Using a resistor is the correct way, just to reiterate.

I dont recommend tapping to charge, but it does work if you dont have the resistor.

Chris

 

[rokke17]

Originally posted by 95EXP4.0
Ok, if I use the resistor what do I have to do and what type do I have to get?

When I have used one in the past they have been mounted on a small chip board and you mount it to the cap and charge it that way.
They are usually supplied with the cap in my experiences

If I was at home I would send you one of my spares, but I am not, so sorry

Chris

 

[EliteConcept]

i know hooking these up are... well if you don't like sparks it will be scary as hell! be prepared for sparks

 

[95EXP4.0]

I like sparks!

 

[Scott_2000]

Here' s some capacitor fundamentals:
* A cap can change current instantly but not voltage
* Charge current in a cap is:
I (current) = C(capacitance) * dV/dT (voltage change per microsecond)
I = C*dV/dT

It's desirable to keep current as low as possible to avoid arcing and keeping capacitor damage to a minimum.


The proper way to charge a capacitor is to place a resistor in series with the positive terminal.

If you have 1 farad of capacitance, then using a

If you don't have the resistor, go to Radio Shack and purchase a 1000 ohm resistor..... 1/2 watt.

Then:
* Attach cap. negative post to ground
* Connect one lead of resistor to the cap positive term
* Connect the 12V lead to the other resistor lead.
* Wait for XXXX seconds
* Remove resistor and attach +12V directly to the cap. positive terminal


!!!! Be Careful !!!! A capacitor will remain charged for nearly an indefinite period of time and can deliver a significant amount of current to the body.

To discharge properly:
* Remove +12V lead
* Connect one resistor lead to the cap pos. terminal
* Connect wire from ground to other resistor lead.

HTH,
Scott

 

[98BlackXSport]

You must be in Electronics of some sort, because that is exactly the way to do it.

 

[Nate1]

Have you ever looked at the PCB of a cap charger? It's easy to tell how it works! You are simply preventing the cap from drawing everything it can outta the battery instantly, and forcing it to go through the resistor. You MAY want to attach the resistor to a heatsink with some thermal epoxy, because if its a farad cap... it will get a bit hot.

Dont go licking the posts... but touching them should be OK as long as you dont have the REM lead supplied with power. But then again with the 12v so close on the other terminal, a good pair of gloves aint a bad idea.

---Nate