To charge a capacitor in a car audio setup with an amplifier, you need to install the capacitor between the battery and the amplifier.
Capacitors are devices that store energy to release in quick bursts. While batteries take a relatively long time to charge and can discharge over a long period of time, charging a capacitor can sometimes take as little as a second, and discharging can occur in a fraction of a second. Accessory capacitors are often used as storage cells in car audio to help power amplifiers that need to drive subwoofers with high bass signals.
An electronic capacitor is usually a simple electrical component built into many circuit board designs that is capable of storing an electrical charge for a period of time.
To charge a capacitor, you must connect it to a power source via a resistor or lamp, usually included with the capacitor, to control the flow of power. Connect one end of the resistor or bulb to the positive terminal of the capacitor, then connect a ground wire to the negative terminal of the capacitor. To actually charge a capacitor, connect a wire from the positive terminal of the battery or power supply to the resistor or bulb and keep it there until the capacitor is charged, usually indicated by the bulb going completely off. A very safe way to do this is to have a fuse between the battery and the capacitor, which you can remove while working with the wiring.
If you want to charge a capacitor in a car audio setup with an amplifier, the wiring will be roughly similar. Instead of connecting the wiring directly to the battery and ground, you will install the capacitor between the battery and the amplifier. The positive wire must go from the battery to the capacitor, and an additional wire must go from the positive terminal on the capacitor to the positive power terminal on the amplifier. On the negative side, connect the negative terminal of the amplifier to the capacitors, then run an additional wire from the capacitor to ground.
When charging a capacitor, keep in mind the danger inherent in the process. A fully discharged capacitor is harmless. Once charged, however, it can release a large amount of energy in a very short time. It’s very easy to get shocked, which makes it crucial that you never connect to both terminals. While car audio capacitors typically don’t carry enough voltage to be dangerous in dry conditions, they can be dangerous if your terminals or your hands are wet. Other high-power capacitors, including those in computer power supplies and older television sets, can be lethal if touched when charged.