Lee
07-14-2002, 05:13 PM
2.8 When my car is running and I have the music turned up loud, my headlights dim with the music. Do I need a new battery or a new alternator? [CD, MO]The headlights will dim because of a momentary drop in the voltage level that is available to power the vehicle's accessories, including the headlights, amplifiers, the engine, etc. This voltage drop can be caused by a very large current demand by an accessory, such as an amplifier trying to reproduce a loud bass note.
The first thing to do is to get your battery and alternator checked for proper functioning. A failing battery can place undesirable loads on the alternator, leaving less power for your system.
If the power system appears to be working correctly, an improved alternator may be required for the large current demands of the audio system. When upgrading an alternator, be careful in your purchase, for there are some potential problems. An alternator which advertises a certain output level may only achieve that output at very high engine RPM ranges, for instance. Also, the new alternator must be adjusted to provide an output voltage within a reasonable range in terms of the voltage regulator.
If you find your car will not start after playing the stereo for long periods of time with the engine off, and the present battery is in good working order, then another, paralleled battery could prevent this embarrassing problem.
Addendum: A common installation problem that can cause this is a poor connection to ground. With greater resistance to ground you get less voltage to your equipment; less voltage means the equipment will try and make up for that by drawing more current. [lh] See item on grounding (http://www.caraudioforum.com/vbb2/showthread.php?s=&threadid=97272)
The first thing to do is to get your battery and alternator checked for proper functioning. A failing battery can place undesirable loads on the alternator, leaving less power for your system.
If the power system appears to be working correctly, an improved alternator may be required for the large current demands of the audio system. When upgrading an alternator, be careful in your purchase, for there are some potential problems. An alternator which advertises a certain output level may only achieve that output at very high engine RPM ranges, for instance. Also, the new alternator must be adjusted to provide an output voltage within a reasonable range in terms of the voltage regulator.
If you find your car will not start after playing the stereo for long periods of time with the engine off, and the present battery is in good working order, then another, paralleled battery could prevent this embarrassing problem.
Addendum: A common installation problem that can cause this is a poor connection to ground. With greater resistance to ground you get less voltage to your equipment; less voltage means the equipment will try and make up for that by drawing more current. [lh] See item on grounding (http://www.caraudioforum.com/vbb2/showthread.php?s=&threadid=97272)