Lee
07-14-2002, 05:26 PM
2.10 Should I install one in my car? If so, how big should it be, and where do I get one? [JSC][note: This is a followup on the question: What is a "stiffening capacitor?" (http://www.caraudioforum.com/vbb2/showthread.php?threadid=97278)
If you have a problem with dimming headlights when you have your music turned up and the bass starts to hit and the engine is running and you don't want to upgrade your alternator, or if the transient response of your amplifier is unacceptable to you, a stiffening capacitor could help you out. The commonly accepted "formula" for determining the proper size capacitor to use is 1F/kW (one farad per kilowatt). For example, a system running at 300W would need a 0.3F (or 300,000uF) capacitor.
To install the capacitor, you should not simply attach it to your power and ground wires near your amplifier, as it will draw very large amounts of current from your battery and could blow fuses (or over charge). Instead, you should insert a small-value power resistor (25 ohm, 1/2 watt) or a 12VDC test lamp in between the power lead and the capacitor, and then charge it. If you use a lamp in series with the cap, when the lamp goes out, the capacitor is done charging. When it is done charging, carefully remove the capacitor's leads from the charging circuit, being certain not to touch the two leads together. You may then permanently install the capacitor by wiring it in parallel with your amplifier (be careful not to short the leads!). Large caps are currently available from some audio dealers, such as Phoenix Gold. You could also try electronics shops or mail-order houses.
CAF comment: We at CarAudioForum.com do not agree with the general idea that stiffening caps are all that beneficial for issues regarding current demand on large systems. We suggest auxiliary (2nd) batteries and/or upgraded alternators -- but this has more to do with large power systems.
If you have a problem with dimming headlights when you have your music turned up and the bass starts to hit and the engine is running and you don't want to upgrade your alternator, or if the transient response of your amplifier is unacceptable to you, a stiffening capacitor could help you out. The commonly accepted "formula" for determining the proper size capacitor to use is 1F/kW (one farad per kilowatt). For example, a system running at 300W would need a 0.3F (or 300,000uF) capacitor.
To install the capacitor, you should not simply attach it to your power and ground wires near your amplifier, as it will draw very large amounts of current from your battery and could blow fuses (or over charge). Instead, you should insert a small-value power resistor (25 ohm, 1/2 watt) or a 12VDC test lamp in between the power lead and the capacitor, and then charge it. If you use a lamp in series with the cap, when the lamp goes out, the capacitor is done charging. When it is done charging, carefully remove the capacitor's leads from the charging circuit, being certain not to touch the two leads together. You may then permanently install the capacitor by wiring it in parallel with your amplifier (be careful not to short the leads!). Large caps are currently available from some audio dealers, such as Phoenix Gold. You could also try electronics shops or mail-order houses.
CAF comment: We at CarAudioForum.com do not agree with the general idea that stiffening caps are all that beneficial for issues regarding current demand on large systems. We suggest auxiliary (2nd) batteries and/or upgraded alternators -- but this has more to do with large power systems.