TSEJEEPERS said:
If that is true then why does the wire that comes off your battery (positive) feed directly into your power distrubition center?
Well without that cable from the battery to the distrubition center you would lose your radio presets,computer memory and everything else that required 12v with the engine off.
This link here is about car audio... it explains it well.
http://www.caraudiomag.com/specialfeatures/0207cae_audio_system_power/
Knowing What's Watt
The biggest mistake made by many consumers (and some installers) is failing to beef up the charging system enough to handle the demands of additional audio and video equipment. Determining how much more electrical current you need depends on the equipment you install. Understanding the electrical system of your car will help you determine how much additional electrical current you need. It all starts with the turn of your car key.
Turning the key in the ignition begins the process of cranking the motor. Your car's battery supplies the electricity needed to get things going. Once started, the car's electrical burden shifts to the alternator. An alternator is a device that uses the engine's mechanical power (supplied by the alternator belt) to create alternating electrical current (AC). The alternating electrical current is rectified (changed) into direct current (DC) which is needed for all the devices in the vehicle that require electricity. The alternator also serves to recharge the car's battery after power is used during the cranking process.
Everything works perfectly so long as the power requirements of the vehicle don't exceed the alternator's power-producing capacity. If the power load is too much for the alternator, then power will be pulled from the battery. If the alternator and battery can't meet all the power needs, then the voltage available to power all the car's electrical devices is diminished. As we learned earlier, when voltage decreases, current flow increases, and current flow creates heat (due to resistance) in components. This is why a prolonged loud bass play sometimes will damage components if the charging system is inadequate.
Alternators are the fastest power source, meaning they can respond to power needs more quickly than the battery or even a capacitor.
Batteries are rated by the amount of cold-cranking amperes they produce. A small import car is likely to have a battery rated at 500 CCA. A large battery would have a CCA rating of 1,000. How big a battery should you install? Most experts say get one as the available space will allow. If your vehicle's charging system is significantly short on amperes, then adding a bigger battery will only create additional problems. Adding a second battery is an option, but is not recommended for a variety of reasons.
"I think multiple batteries are a bad idea for vehicles that are daily drivers," says Jeff Triplett, director of technical services for Memphis Car Audio. "A second battery has to be charged by the alternator just like the primary battery, so you're just creating more work for the alternator. If the motor is off and the system is running off battery power, the multiple batteries are OK. However, daily drivers simply have little to gain from multiple batteries."
Another strike against having multiple batteries is the safety issue. Batteries can be dangerous if improperly installed, so great care should be taken if you are thinking of putting in a battery in a non-stock location. Consult a qualified installer if you feel you must have a second or third extra battery.
