If you think that all you need is a big amplifier and huge speakers for a true high power audio system, you may have overlooked something. Adding high power car audio components to your vehicle without an adequate power supply system may lead to disappointment, frustration, distortion and damaged equipment.
Let's say you install a 1000 watt RMS amplifier in your car. The vehicle's charging system must produce sufficient current to run the amplifier. How do you determine how much current is needed? Simple: divide the RMS power rating of the amplifier by the amount of voltage your cars electrical system will produce.
Most vehicle electrical systems will produce approximately 13.8vdc with the engine running. Thus, 1000 watts RMS (doubled to allow for the max, in this formula) divided by 13.8 volts, draws around 145 amperes of current. The electrical system of the vehicle will need to produce an extra 145 amperes of electrical current above the basic requirement of the car, to operate your amplifier and it's woofer at a high performance level.
One of the biggest mistakes made by consumers and even a few installers, is failing to ensure enough additional energy resources to handle the extra load of the audio system. But first you must understand how the electrical system operates. Here's a brief summery.
Engaging the starter begins the process of initiating the system. The battery stores enough kinetic power to operate the starter. Once the engine is running, the electrical burden is shifted to the alternator. The alternator uses the engine's mechanical power to produce electrical (AC) current. The AC current is rectified - changed to DC (direct) current, which is what operates, all the electrical devices in the vehicle. The alternator also provides enough residual energy to recharge the battery.
Everything works well so long as the total power requirements of the vehicle do not exceed the capacity of the alternator's output. If the output is overloaded by an excessive draw, then power will be drained from the battery. If the alternator and battery combined cannot meet the demand, then the vehicles electrical devices may begin to fail. As voltage drops, current (amperage) draw increases, and that increases heat in wiring and components. This is the reason that loud bass will sometimes damage components if the power supply system is inadequate.
A first consideration to determine if the charging system is adequate is the alternator itself. If possible, look for the maximum output, or HOT RATING on the alternator. If this information is not available on the car, call a local parts store or car dealership and ask them to look up the stock alternator for your vehicle. The hot rating indicates the amount of power the alternator will produce once the engine reaches it's normal operating temperature. With this information, you can determine if the charging system has sufficient capacity to accommodate your power audio system. If your components will draw more than 20 amps over the hot rating of the alternator, you may want to consider a high output alternator. If only a little extra current (12 to 19 amperes) is needed, the easiest way to enhance the system is to add an extra battery, or replace the existing battery with a larger one. If the difference is less than 5 amps, the existing power system will be able to handle it. For this, a capacitor is the best solution for every system, regardless of the presence of an adequate, but slow acting power supply.
The load imposed by audio signals is usually not constant, but will vary with the greatest draw occurring in peaks of a relatively short interval. It is for this reason that the fuses recomended for most amplifiers are rated at slightly less than the max theoretical current. Keep in mind, that it is desirable for the fuse to blow before the amplifier does.
We strongly recommend that if you anticipate making any changes to your car's electrical system that you engage the services of a professional. Keep in mind that any increase in generating capacity/load will usually diminish to a small degree, the cars available horsepower.
