Installing Capacitors - How To

This month I took a break from my Civic Si build project to look at a subject that I'm frequently asked about-capacitors and how to wire them correctly. Here is a hands-on approach to install capacitors and trunk-mounted batteries.

To start, I'll explain what a car audio capacitor really is. It's a storage device for electrons (electricity) and is very similar to a battery. But the main difference between the two is that a battery uses chemical reactions to produce the electrons while a capacitor simply stores energy. A capacitor consists of two conducting plates separated by an insulating piece or dielectric. Car audio capacitors store energy for dynamic peaks, which can greatly improve your stereo system. Extra batteries produce and store energy for extended play on your stereo system. Capacitors discharge very rapidly, while batteries tend to discharge very slowly.

Capacitance, or the amount of energy stored, is measured in farads. Most car audio capacitors are one-half, or 1 farad. Capacitors should be pre-charged before installation. This enables them to reach their maximum storage limit without damaging the electrolytic. It also allows the unit to be installed without arc-welding your connection to the teminal. Use care when charging a capacitor and always do it with a resistor. I typically use a 100-watt, 8-ohm resistor, available at most electronic surplus stores. Most caps come with a 1K resistor, which will work but will take a while and the leads will get extremely hot. If you must use this resistor, hold it in place with pliers. First, ground your capacitor. Then, before connecting 12-volt power to your cap, take out the fuse under your hood and put the resistor in its place. Basically, just touch the leads where the fuse would normally go. Next, connect power to the capacitor. It's also a good idea to have your voltmeter monitoring the cap's terminals so that you can watch the charging process. Once the cap gets up to 12 volts you can take out the resistor and reinstall your fuse.

Capacitors should be placed within inches of your amp in order to maximize the performance of your system. It's also important to remember that, while a fuse should be used to protect your system, it must be placed on the charging line feeding the capacitor, NOT after. A fuse inserted between the capacitor and amplifier becomes a resistor, essentially rendering the capacitor useless.Next month we will continue on with the Civic build and take a look at the creation of some custom parts of the car. Until then, e-mail me your thoughts and questions: info@jasonsyner.com.