Understanding the math of electrical loads

For the young'uns and their 2 kilowatt stereos, listen up. First and most important, do not try and wire this any distance or use the starting battery. Odysessy AGM batteries are your best bet for monster amplifiers due to their dual personality of being both a deep cycle battery and the highest cranking amp battery per pound of battery weight you can buy. Mount the AGM battery right with the audio amplifier so that your leads are heavy and very short in total lenght. Now you can run that easy-to-work-with 12 ga from your alternator or starting battery back to the AGM for charging. This is why the above method is the ONLY way acceptable and yes it involves math again. Your stereo amp if in fact is a true 2000 watt unit, it is running class A, so efficiency is about 50%. So, 4000 watts input, again divided by 10 volts (remember the voltage drop under heavy loads) = 400 amps. Do  you think 20 feet of 8 ga is going to carry this? Nope.  

Now, a little 15 lb Odysessy will lay down 680 amps for 5 seconds. If you want to blast your tunes for more than 5 seconds to be truly obnoxious, don't worry ,you can. That current draw is at peak output and that doesn't happen often or for a few milliseconds at a time. With the engine running and sending 15-20 amps back to the AGM battery, you're good to go. Another misconception is large amps burn out your tweeters, but believe it or not it is small amps that burn out the tweeter. When an underpowered amp is turned up so loud that the amp is clipping the wave form, you burn out the tweeter. Clipping is a distortion that muddies the sound and is caused by the amp running out of output voltage swing and clipping the top and bottom of the waveform. Looking at clipping on a scope, instead of seeing a nice completed sine wave the tops and bottoms are a horizontal line which is DC, no longer a frequency. What keeps a tweeter healthy is the fact that its voice coil is moving in and out 8000 to 20000 times a second and that motion keeps the voice coil from burning up due to the moving air keeping the voice coil in an acceptable temperature range. So when the underpowered amp clips at high settings the tweeter is seeing DC, so a lot of heat energy to dissipate but because it is DC, the little sucker isn't moving, so smoked. Radios in new cars no longer will clip because what you think is the volume control potentiometer is in reality just a shaft with a slotted light chopper wheel and as you turn up the volume, each time the light from a led passes through a slot to a light sensor on the other side of the wheel, it requests if you will the ramping up of volume but now can employ control circuitry that stops short of clipping, thus saving the speakers and warranty claims.