Car Audio Central - Ultimate Car Audio Forum and Community

addendum;
also remember to replace your 'big three' with the same size power cable as you run to the amps.
-motor ground cable
-alternator to battery
-battery to ground

is your uncle an electrical engineer?
I am.
let me clue ya both in here.
house current is AC. car systems are DC.
this makes a huge difference in the amount of heat you're going to create drawing large amounts of current through the cable.
This is also why speaker wire, which is high voltage AC, is so small compared to the power wire supplying the amplifiers.
Remember high power car audio systems can draw over THREE HUNDRED AMPERES OF CURRENT continuously. House circuits are usually 60A at most, and that can handle 3 or more rooms of the house.
Think about that one for a moment.

The use this chart to give you a feel for wire sie requirements:
[url]http://www.the12volt.com/info/recwirsz.asp[/url]
read this to learn more about electrical principles than your uncle apparently knows:
[url]http://www.bcae1.com/wire.htm[/url]

and finally, read this to learn more about battery types:
[url]http://www.wickedcases.com/HT/batteries.html[/url]

hope this clears up any doubts ya had.
using too small of a wire for power will cause clipping in your amplifiers, as well as extreme heat build-up which can melt the cable insulation and cause a short, and subsequent fire. Unless you really want to play with setting your car on fire, or destroying your amps and speakers, I'd recommend strenuously that you use the right size cable.

there is a point where it can be too big, and a waste of space, its just that most do the math before hand and figure what is appropriate for cost.

example: one amp produces 1000w at 12v. thats 84A of current flowing through copper wire 20' long. this much current through a 1/0 cable will have like 2m ohms resistance (thats .002 ohms). the same current through a 2 gauge cable will have 3m ohms resistance (.003 ohms).

a difference of just less than .2v loss. for the average enusiast and system, thats harmless. when it gets to heavy spl competetion that might be unacceptable.

just to put into perspective the voltage loss and resistance of wire. very serous competitors will go through this calculation before buying wire. its fairly accurate in determining which wire size will be appropriate.

*edit - btw, this math would be given that the amp was 100% efficient, which is never so. this is just an example, not a perfect calculation, but the in the same respect, the ratio of voltage loss would stay the same.

x3.....i'm going all 1/0 wiring in my next vehicle.....no need to upgrade wiring at all then......your uncle might know how house electrical works but cars i highly doubt.....big difference in the way things run thru the wiring.....resistance=heat=power loss.....or total melt down of wire and car fire.....

[quote]There is no such thing as overkill when it comes to wiring.[/quote]

x2

You can never have a wire that has too little resistance to it.

There is no such thing as overkill when it comes to wiring.

tell your uncle to take a class about the differences between AC voltage, and DC voltage.. and also the relationship between voltage and current.. and how resistance of copper wire plays into the scheme of things..

or laugh at him.... and tell him he's wrong. :)

Loyd L.

also remember that your house is AC and about 120v.

in a good circut you dont want more than 3% loss in voltage across the power wire. yes, the power wire does have resistance. if it is small, and you try to shove a lot of current through it, you will end up losing a lot of voltage. this is why you need to use such large wire.

bigger is better

Overkill?

Well its not overkill if you did the math and it shows you need it. YOu dont want to have your power wire melt, not fun!

It is also very important to redo the factory wiring from the alt~batt and the engine block ground!

As for the front battery you will be fine with his sugguestion.

well my uncle came and looked at my alt./battery today. He saw my power wire and he freaked out. He said:
"You went a little overkill on this here. Do you know the wire going to your house is smaller than this. And that powers everything, oven, microwave, all that"

I asked him if I should upgrade my alt/batt wires and stuff and he said they were already plenty big enough.

I dunno we'll see. He claims it willb e fine but that i should get a new battery..he said not to get deep cycle though, cause they die and dont have long warranties. Costco (wholesale store by us) sells these 60$ batteries with 900/1000 CCA and CA with 6year warranties...so i think ima get one of those.


but i dunno, he said the only time ill need a lot of power is when im idling at a light and i crank my system up.

we'll see whose right, math and all the car audio guys or the engine/mechanical/old guru.

im anxious because my uncle is always right and always has something to critisize me about.