Automotive Power Capacitors
Popular upgrades for many car audio enthusiasts are power capacitors. These are devices that get mounted near the car’s 12 Volt battery, or on the cable by the audio power amplifier(s). Their advertised purpose is to add “additional power,” meaning that they can add electricity to your car’s electrical system when needed. This is especially important, the advertisers say, when you have a powerful audio system in your car.
Car power capacitors are typically round tubes, about 3 inches in diameter and about a foot long. They usually have la terminals that get mounted to the positive terminal of your car’s battery and to a good ground point. They are sold at many auto parts stores and on the internet.
The technicians at Efird of Florence, a Chrysler, Dodge, Jeep, Ram dealer in Florence, SC, say it is important to know that capacitors aren’t “another battery.” They do not store electrical power like a battery does. What capacitors do is make the existing power supply stronger. In other words, when a high demand is put on your car’s electrical system, say when your audio system pumps out loud bass notes, the normal voltage (12.6 Volts) coming out of your battery will sag just a little bit. It may drop to let’s say 12.4 volts. With a good-sized power capacitor added to your electrical system, the 12.6 volt wont sag when your audio system needs power.
With audio power amplifiers getting bigger and bigger, some people are noticing that their headlights dim a little when playing deep bass music loudly. By adding the right size power capacitor, the car’s battery power supply is made stronger so headlights don’t dim. Some also believe that a power capacitor will make their sound system sound better. If you are using huge power amplifiers, adding power capacitors may help prevent the amplifiers from getting voltage starved and affecting the sound quality. It is important note that they don’t actually make your system sound better, it just prevents your power amplifiers from getting starved for power.
The general rule of thumb is to put in 1 Farad of capacitance for every 1,000 watts RMS of total audio system power. There are some installers who advise larger capacitors, and there is nothing wrong with that. In fact, many see benefits with 2 or 3 Farads per 1,000 watts RMS. The larger the cap, the stiffer the power supply from the battery is.
Conclusion: Do you need a power capacitor in your car? It depends, if you have a powerful audio system and you notice your lights dimming as the audio pounds out deep bass, then you probably do. If you have a standard audio system in your car, say one from the factory, don’t waste your money. A power capacitor won’t make your audio system sound any better.