Wiring to battery or distribution box?

[jssong]

Im not quite positive what to call it, is it the power distribution box? above the battery? well the shop that installed my audio stuff, didnt have any 1/0 awg ring terminal, so they used about a foot of 4 awg, then my inline fuse holder, then about 15 feet of 1/0 gauge power wire. I bought a battery terminal, but they didnt use it. I went to the guy and talked to him, he said on later model cars, itz good to go from the power distribution box because you want to start closest to the alternator, which comes directly to the power distribution box, and not from the battery.

Is this correct? or should i just buy some 1/0 awg wire, and wire it to my battery terminal? or just get a 1/0 ring terminal and just change the 4 awg to 1/0 awg and keep it wired to the power distribution box?

 

[expo5.0]

hmmm- i've never heard that... makes me wonder about my own 0 gauge installation- i hope i did it the best way

 

[jssong]

well ive noticed most people run it wiht battery terminals, and even the guy at www.thezeb.com told me to do it to the battery. so thats what i figured. but the audio shop guy said wiring it to the power distribution box will less likely hurt the battery, because it drawing power directly from the alternator, and will help save battery life.

 

[expo5.0]

yeah i have terminals with 0 gauge, two 4 gauge, and 2 8 gauge and their all used- lol on my red top.

it makes sense to me to go directly from the battery so far as i know thats the way its supposed to be done. i had never heard it recommended to do it the way you suggested before, but your reasoning does make some sense though

 

[jssong]

where are the audio gurus... any ideas?

 

[expo5.0]

the answer here is to upgrade the wiring everywhre under the hood. if its all 0 gauge (4 gauge is probably fine for some too) then this issue no longer exists.

 

[ShadowA2J]

Well first of all, the fact that you have 1 foot of 4 gauge with your 1/0 gauge, basically means that you have all 4 gauge wire. the 4 gauge only lets so much power through, just because the rest is 1/0 gauge doesn't mean the whole thing gets the power that a 1/0 gaguge wire would allow. I would pull the 4 gauge off and just run it right to your battery with a terminal.

 

[metalhed]

<edit>

Nevermind.. Misread the thread.

 

[expo5.0]

thats not entirely true shadow... a short length of lesser gauge wire will flow as well as a long lenth of larger wire. so a short piece of 4 gauge doesn't completely ruin everything.

 

[ShadowA2J]

Originally posted by expo5.0
thats not entirely true shadow... a short length of lesser gauge wire will flow as well as a long lenth of larger wire. so a short piece of 4 gauge doesn't completely ruin everything.

Really? I've always been told differently. It doesn't make any sense as it to be the other way though. It's like trying to pass a 1/2 gallon of water through 3 gallon containers one at a time. At the end you still end up with 1/2 gallon that you started with, even though there was room to pass a gallon at a time through the last three. If that made any sense. You know what I'm sayin? I'm not doubting you, just doesn't make sense to me.

 

[jssong]

that short length of a wire really shouldnt have that much affect on the power issues. If you i used 4 awg through the whole truck, then it would be a problem, but 8 inches really isnt much. but still nobody really knows ??

 

[izackary]

expo is correct. there could easily be the same resistance in that length of 4-gauge, as 15 feet of 1/0. I don't know the exact numbers of this size, but i have numbers of 14 and 16 gauge (speaker wire size): 1000 feet of 14 gauge has 2.5 ohms of DC current, whereas the same length of 16ga has 4 ohms. basically, short lengths aren't a big deal in day-to-day use.

 

[Crankcase]

Say the 4 guage can carry 10 amps, and the 1/0 guage can carry 20 amps. By putting even that little piece of 4 guage wire in there, you are limiting the 1/0 guage to 10 amps MAX. That is what Shadow is trying to say.

NEVER put a smaller guage ahead of a bigger guage in any electrical setup, car, or home......

jssong, Replace the the little 4 guage piece with 1/0 guage, it will raise the whole capacity of the length of wire.

 

[expo5.0]

thats not how it works though

if they were equal lenth that would make sense, but the resistance in a shorter length of cable is much lower.

 

[expo5.0]

here's one calculator for this- probably not perfect, but its the first one i got in a google search-

http://www.partsexpress.com/resources/cablecalc.html

 

[jssong]

so keep the wiring to the power distribution box? or battery?? lol

 

[expo5.0]

i'd go with to the battery. that guy is the only person i've ever heard give that reasoning

 

[ShadowA2J]

Originally posted by expo5.0
i'd go with to the battery. that guy is the only person i've ever heard give that reasoning

I agree with Expo5.0 on this one, wire it to the battery, I've never heard of doing it the other way.

 

[boominXplorer]

i would take it off of the dist. box and run it to the battery. Its easy to kill an alternator when hooked to it with any amp on. when an alt says 90 amps that means 90 amps with the revs high. With anyhting larger than 4 awg wire than i suppose you have a big system. The best way to have it is add up all your fuses on your amps and add 10. if that is equal to or below your alt. rating your good. if not you need a bigger alt. after all this is $.02 worth -> HOOK IT TO YOUR BATTERY

 

[Crankcase]

Originally posted by expo5.0
thats not how it works though

if they were equal lenth that would make sense, but the resistance in a shorter length of cable is much lower.

The piece of 0/1 guage that he would have to put in to replace the short 4 guage piece would be an equal length to the piece he just took out, so it would have less resitance.

The drawing below shows what I mean...
------- ----------------
0/1 ------------- 0/1
-------------
------- 4 ----------------

If he replaced the 4 guage in that drawing, the whole "pipe" would become larger, because he isn't adding any length.....