Determining the Current Capabilities of Your Vehicle
Before installing a power amplifier in your system, you should take into consideration the vehicle’s ability to provide adequate current to the amplifier. In most vehicles, the alternator is only capable of supplying a little over the requirements for the standard electrical system (i.e. headlights, air conditioning, etc.).
Depending on how you play your system will determine the amount of current you will need. For example, when you listen to your system at low listening levels, then you’ll probably use less than one-third the rated current draw. If you play your system at loud levels, then you will use most of the rated current of the amplifier.
Most alternators have about a 40 percent reserve capability. In order to determine how much ampere of current you will have for your system, you will need to find out what your alternator is rated at. If you’re not sure of the total amperage of your alternator, a good place to look is on the alternator itself. Most alternators have a metal tag stating the total average available. If you can’t find the tag, check with the manufacturer to find out the rated amperage. Once the rated current of the alternator is determined, you need to multiply this number by .40 in order to determine the reserve current available for use with your power amplifier.
Example:
Alternator = 80 Amps 80 x .40 = 32 Amps
Please keep in mind this is an estimate only, not exact science. It is best to get your electrical system tested by a professional to determine electrical system's true capabilities.
Calculating Amplifier Current Demands
By using the fuse value of the amplifier you can get a rough idea of the amount of current draw that will be used under full output power. Although the full output rating is good to determine the total amperage draw in the system, it does not represent the true continuous or average amperage draw in the system. Listed below is a simple way in order to determine the approximate continuous current draw of your amplifier.
- 1.) Determine fuse value of the amplifier.
- 2.) Divide the RMS power rating by the peak power rating.
Example: 50 Watts RMS divided by 100 watts peak power = .50 (50%)
Once you figure the percentage of RMS vs. peak power, you multiply the fuse value of the amplifier by the RMS percentage.
Example: If the amplifiers fuse value was 30A, then 30A multiplied by 50% would be 15A of continuous current draw.
Upgrading Your Electrical System
Depending on your system's current requirements vs. your electrical system's capabilities, you may need to upgrade your system. For example, if you find that you headlights dim when you have your system cranked up while driving at night, this is a sign you should upgrade your electrical system.
There are several different ways in order to accomplish this; one, upgrade the alternator so that it has a higher amperage output, or two, purchase a capacitor. We recommend to consult your car audio retailer to determine what is best for your system.