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Published on January 2, 2008

Simply put, it is a battery for feeding electrical energy for the car-audio system. Rather than explaining it fully at the fair, I decided to give an in-depth answer here.

Generally, a car-audio system requires direct-current (DC) power, while home audio uses alternating current (AC).

A battery is a device that converts chemical energy directly into electrical energy as a source for all of a vehicle's electrical devices, including the audio system. The battery gives out electrical energy when the engine is running. In order to have good sound quality from the audio device, the battery should provide sufficient power.

Where does a battery get its electrical energy? The answer is the dynamo charger, often known as the alternator. Alternators are used in cars to charge the battery and power the electrical system when the engine is running. When the engine spins the alternator around, the alternator induces an AC voltage that is converted to DC via a set of rectifiers and used to charge the electrical system.

Alternators are normally linked to the car's on-board computer system, air- conditioning, front lights, tail lights and so on. While the alternator provides electricity to other parts of a vehicle, it also simultaneously charges the battery. In general, alternators used in passenger cars produce 35-45 amps of electricity, although higher ratings are becoming more common.

If more electricity is required for large audio systems - for example, 65 amps - adding a second battery would certainly help. However, too many batteries can overload the alternator and eventually stall it.

The capacitor's purpose is to provide a sort of reserve power source from which the amplifier can rapidly draw when it needs it - such as during a peak signal - as well as to stabilise the voltage level for the amplifier.

Installers therefore recommend that audio-grade and high-powered capacitors be used in top-end audio systems for high-quality sound.

Most audio-grade, high-powered capacitors will be the electrolytic type, which can be quite costly. Also, to cope with noise some installers put in a capacitor connected to the dynamo charger, so as to ground the electrical current.

All three elements - capacitor, battery and dynamo charger/alternator - are inseparable for a car-audio system and great music on the road.

By Wijit Boonchoo

The Nation

Ultimate in Luxury

The Luxury LS 460 is a wonderfully comfaortable car fitted with all mod cons, althoough not necessarily the most fun vehicle to drive.