Power Capacitor Functionality: Why You Need a Cap
Car audio capacitors are electrical circuit elements used to store charge temporarily. Capacitors are usually either cylindrical or rectangular in shape and generally consist of two metallic plates separated by a dielectric. As a temporary power source, the capacitor is able to provide voltage quickly and on demand to components. Throughout a musical performance, different peak demands are required. These peak loads require large current bursts in short spans.
Capacitors charge and discharge very quickly and can provide power faster to the amplifier than the car battery and alternator. This is because the car battery’s internal resistance is a lot higher than the resistance found in a car audio capacitor. This resistance restricts the flow of current generated by the alternator and battery. This is why you may need an audio capacitor to help supply power to your amplifier. Capacitors stabilize the amplifier, keeping the amplifier cooler, reducing distortion and enabling it to run more efficiently.
You should select a capacitor that can store enough power to feed your amplifiers. The capacity of a capacitor is measured in farad. A farad is the measurement unit used to determine the size of a capacitor. One farad to 500 watts RMS is the ratio used to determine the size of capacitor needed to supply enough power to an amplifier. While using a cap much larger than recommended will not damage an audio system, it is not recommended because of the unnecessary strain it puts on the vehicles electrical system.
How do you determine whether or not you need to add a capacitor? The most noticeable indicator is dimmed headlights. When your headlights dim, it indicates a power shortage. This shortage is likely due to an amplifier demanding excessive current. Adding a capacitor will most likely solve your problem. However, sometimes a audio capacitor alone won’t help fix dimming headlights. If your headlights dim only when the vehicle is in idle, then a cap will probably rectify the problem. If your lights dim as your engine's RPMs climb, then there is a problem with your vehicle's electrical system. This will require upgrades to either the alternator or battery, or both. Always check your battery and alternator before adding a cap.
Another way to figure out whether or not you need to add a cap is to calculate your amplifier’s current draw. Figure out the amount of draw required on the amplifier owner’s manual and keep in mind your personal listening habits. You will have about 30% of your maximum alternator rating available to power your amplifier. So if your alternator rating is 70 amps, then you will have around 21 amps to work with (and marginally more or less depending on what other components are running in the car). Your current draw should be less than this number. In this case, lower than 21 amps. If you decide you need more, you will need to add a capacitor.
The type of capacitor you need depends on your vehicle, amplifier setup, and musical taste. If your vehicle has a smallish alternator and battery setup, you will probably need to add a capacitor. If you install big, high-current amplifiers, then you will probably need a capacitor. Lastly, if you are inclined towards deep bass music, a capacitor could be useful in that it will provide the short bursts of power required to handle this musical style.
If you still have additional questions about when and why you need a capacitor, give us a call at 1-877-289-7664.
About the Author
Written by Gary Brikowski