How to connect a capacitor?

CAR AUDIO Basics – How to Connect a Capacitor?

Capacitors are common in advanced car audio systems. In automotive systems, we commonly use 12V DC. Most car manufacturers place the battery in the engine compartment. This is dictated by the need to provide power to power-hungry components such as the starter motor and lights. Furthermore, a short cable route from the alternator improves the charging system's efficiency.

Installing a capacitor in a car.

When installing an amplifier for a sound system in the trunk, we must consider the need to build a new, high-current power supply circuit for our audio system. A good car audio system can consume enormous amounts of current, so the diameter and quality of the wire used are crucial. Unfortunately, every wire offers resistance to current flow.

With a typical 5-meter cable, the potential difference between the battery terminals and the amplifier terminals adversely affects the operation of the internal converters powering the amplifier's electronics. And that brings us to the capacitor. The capacitor is installed at the end of the cable added for audio purposes.

Wires to the capacitor.

But the method is not unimportant. For proper operation, we must ensure its electrical installation. In short, the capacitor must be connected in parallel to the battery, but at the opposite end, farther from it. The same applies to the crucial ground connection. The capacitor's ground must be connected to the same point as the amplifier's ground, not to the amplifier's GND terminal! This allows the node to maintain potential and bypasses the harmful resistance of the ground wire. A perfect zero ohms at this node is crucial. Some amplifiers also feature additional capacitor terminals, but these are few and far between.

Parallel operation of capacitors.

When operating in parallel with a battery, a charged capacitor releases its stored charge when the audio system's power demand increases. This is particularly useful for reproducing the lower bass frequencies. This improves amplifier performance and ensures stable parameters. The larger the capacitor's capacitance (measured in Farads), the better. Of course, don't overdo it, as the cross-sections of the power cables are more important, and they, not the capacitor, limit the overall system's power. A functioning capacitor will also eliminate unwanted interference in the car's electrical system. A good capacitor is not only a reservoir of energy but also a voltmeter and electronics.

Voltmeter installation.

The voltmeter located inside the capacitor housing is activated by an internal current sensor and displays the voltage level at the amplifier's power supply during operation. With a well-designed installation, the display remains off for most of the operation. Increased current demand activates the voltmeter. Because the current sensor in the capacitor is ineffective at constant low power consumption, we may feel it is not working. In fact, the capacitor is constantly active, and turning on the display indicates high current consumption, for example, to power a subwoofer. A constant voltmeter display would drain the battery of an inactive car.

Checking after installation in the car.

A properly installed capacitor is an important element of the power supply circuit, and in the case of an installation with two or more amplifiers, it's absolutely essential. Adding a capacitor to a poorly designed and calculated system will not help much, and in extreme cases, it will damage the amplifier. Therefore, be careful during installation. A multimeter with an ohmmeter is essential. Before connecting the capacitor to the system, charge it using the included resistor or a 10W/12V light bulb. The charging procedure is described in the installation instructions and on the manufacturer's website. Compliance with the laws of physics will prevent problems and ensure long-term, trouble-free operation of your car audio system.