Originally posted by: nboy22
Originally posted by: PurdueRy
this thread is going places.
OP, I still have no idea what you are trying to accomplish. Which is quite impressive considering I am an EE.
With car audio capacitors for amplifiers/subwoofers they come with a small resistor for the initial charge. I can't remember what it is for because high school electronics class was a few years ago. I believe it has to do something with how capacitors can be ruined and/or other safety precautions.
EDIT:
" Charging large capacitors:
When connecting a large capacitor (1/2 farad or larger) to the 12 volt source, you may want to charge it slowly before making the final connection to the power wire. Most capacitors come with a resistor to charge the cap slowly. If you're working on your system, and disconnect the capacitor, the cap may get discharged (something might accidentally touch across the terminals or it may partially self discharge over time). If you can't find the original resistor to recharge the cap, you can recharge it with a standard test light (you know, the one with a light bulb, not one of those fancy pants test lights with LED indicators). There's a somewhat helpful demo near the bottom of the page.
If you don't have a test light and want to use a resistor to charge or discharge your capacitor, use a ceramic encapsulated high power resistor like the one below (I'd recommend using a resistor rated for 10 watts or more and about 20 ohms). If you use a small resistor (i.e. a 1/4 or 1/2 watt) of too low value (less than 100 ohms), it may get hot enough to seriously burn your fingers.
REASON:
The reason you may want to charge a cap slowly is to reduce the arcing involved with fast charging. This arcing won't hurt the cap but it might damage the chrome or gold finish on the connectors."
- Taken from
Here