Battery choices

[JackG]

Originally Posted by edevlin

"As you point out yourself, the battery is ~12V, while the alternator produces ~13.6V. An accurate analogy of voltage is water pressure in a pipe. If you have two pipes connected together in a "Y" that then go to a sprinkler, and one pipe has a higher pressure than the other, which pipe will be feeding the sprinkler? The one with the highest pressure, of course! The lower pressure pipe will in fact reverse it's flow until the pressure equalizes, which is how the battery charges!"


So, based on your discussion, if I wanted to provide more current to my outboard audio amps which are wired directly to the to the battery) the best strategy would be:


1. Get a higher output alternator

2. Get a larger battery

3. Stick a large cap in the circuit from the battery to the amps


I am especially curious about the third case. My current setup seems to be working fine, but when I had a smaller battery (11 lb Braille) in the car, when I was driving with the headlights on and the music playing loud, you could see the dash lights dim in rhythm to the music at high (very) high volume levels. With my current 15lb Braille battery everything seems to be working fine, but I am still curious about a large cap in the circuit.

Ed

:dance:

What you were seeing is voltage drop across the resistance in the car's wiring, and also internal resistance inside the battery. The more current you pull, the larger the voltage drop.

Since you are wired directly to the battery, you're seeing the drop in the wiring from the alternator to the battery. You old, smaller battery also likely had a higher internal resistance, so it was less able to keep up with the dynamic current demands of your audio setup. You new larger battery probably has less resistance, and while replacing it you may have created better connections at the battery as well, which would help.

The big capacitors are placed as close to the amp as possible, and are there to provide a low resistance path for providing those short peaks of high current that the amps need for musical peaks. Capacitors are basically energy batteries that can release and recharge their energy very quickly and easily. The end results is you will have less distortion during peak power demands. Whether you'll hear the difference depends on your equipment, musical taste, and ears.