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Old 04-06-2010, 08:12 PM   #1
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Default Is wire wire?

I am looking at new battery wire for the car. Better grounds, and better power transmission being the goal. In looking around for 2 AWG wire, I have found lots of different stuff, from Monster Cable to wire from the battery store. It is all listed as 2 AWG but some have more / smaller strands than others to make up the size. The outer coatings are different as well. I know I don't want one solid strand of copper, but is there a noticeable difference in one over the other? There sure is a difference in price.

Function over form is the rule here, which is why this is in the track prep forum rather than the stereo and what wax to use on the door jam site.
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Old 04-06-2010, 08:16 PM   #2
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Cable of the same gauge with a lot more small wires is easier to route and less subject to damage from vibration/flexing
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Old 04-06-2010, 08:18 PM   #3
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Gotcha'

But is 1000 strands better than 100?

ie
is

better than

?
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Old 04-06-2010, 08:20 PM   #4
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Quote:
Originally Posted by Chris Swearingen View Post
Gotcha'

But is 1000 strands better than 100?
Yes, but probably not for our purposes.
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Old 04-06-2010, 08:21 PM   #5
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To a pretty big degree, yeah copper wire is copper wire. You want to make sure that the jacket is automotive grade, and higher strand counts will offer increased flexibility.

That aside, 2ga? Man, that's insane! That's like 2.5x the cross section of 4 ga, which is already overkill.
I think replacing your wiring with 2ga will do nothing but make the car heavier, but perhaps that will be offset by the lightening of your wallet! There's no reason I can think of to run 2ga from the battery up.
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Old 04-06-2010, 08:22 PM   #6
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Quote:
Originally Posted by Chris Swearingen View Post
Gotcha'

But is 1000 strands better than 100?
What Bruce said. There is a phenomenon known as skin effect that can require a high strand count in certain high frequency applications... that has absolutely nothing to do with this use.
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Old 04-06-2010, 08:28 PM   #7
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Quote:
Originally Posted by Ben View Post
To a pretty big degree, yeah copper wire is copper wire. You want to make sure that the jacket is automotive grade, and higher strand counts will offer increased flexibility.

That aside, 2ga? Man, that's insane! That's like 2.5x the cross section of 4 ga, which is already overkill.
I think replacing your wiring with 2ga will do nothing but make the car heavier, but perhaps that will be offset by the lightening of your wallet! There's no reason I can think of to run 2ga from the battery up.
According to this chart maximum amps for power transmission of 4 gauge is 60, for 2 gauge it is 94. I am running a 70 amp alternator so.... I may not ever really be transmitting the full 70 amps but ...

Am I reading from the wrong column and need to be looking at the maximum amps for chassis wiring?
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Old 04-06-2010, 09:07 PM   #8
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Your alternator may be rated at 70 amps, but not for long. That's peak, and only for short bursts. Otherwise you'll melt the windings.

4 gauge is plenty for automotive applications.
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Old 04-06-2010, 09:19 PM   #9
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Here is a much better resource, that actually takes wire length in account.

http://www.stealth316.com/2-wire-resistance.htm

8ga is ok for a miata. 4ga is overkill.
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Old 04-09-2010, 04:21 PM   #10
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the more strands, the more power it can carry. a good car audio 8ga. wire can nearly transfer as much power as a cheap automotive 4 gauge.
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Old 04-09-2010, 04:47 PM   #11
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Solid core for AC, as many strands as possible for DC is what I was told and have been practicing so far.
AC travels in the core, and DC travels on the surface of the wire.

4ga, if it is quality wire, should be plenty IMHO.
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Old 04-09-2010, 05:05 PM   #12
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Quote:
Originally Posted by spoolin2bars View Post
the more strands, the more power it can carry. a good car audio 8ga. wire can nearly transfer as much power as a cheap automotive 4 gauge.
I don't know about that. You might want to check your source.

Skin effect is not a problem here. Strand count only really impacts flexibility.
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Old 04-09-2010, 07:06 PM   #13
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Quote:
Originally Posted by spoolin2bars View Post
the more strands, the more power it can carry. a good car audio 8ga. wire can nearly transfer as much power as a cheap automotive 4 gauge.
I don't think it has anything to do with the # of strands. In telecom when you need to transfer a lot of power at DC, fewer strands of a larger diameter are used.

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Originally Posted by Godless Commie View Post
Solid core for AC, as many strands as possible for DC is what I was told and have been practicing so far.
AC travels in the core, and DC travels on the surface of the wire.

4ga, if it is quality wire, should be plenty IMHO.
Thats the exact opposite of what they teach in electromagnetcs. The higher the frequency the closer to the skin it travels.
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Old 04-09-2010, 07:52 PM   #14
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Quote:
Originally Posted by TurboRoach View Post
Thats the exact opposite of what they teach in electromagnetcs. The higher the frequency the closer to the skin it travels.
Indeed.

At high frequencies, this is an issue. 60Hz is not a high frequency. Solid-core wire is used for household AC because it is cheaper to manufacture, easier to terminate, and has a greater current-carrying capacity per actual diameter, and since houses tend not to move much (well, apart from here in CA) the flexibility afforded by stranded wire is simply not needed.

The only places where you'll typically find stranded wire in mains-level AC use are where you are feeding a high-current load (such as an electric oven) and a solid wire of sufficient size would simply be unbendable, and where you actually do have to accommodate movement, such as when controls are mounted on a hinged panel or when you have a large motor set upon a vibration-absorbing mount which permits it to move as it operates.
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Old 04-10-2010, 12:09 AM   #15
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Quote:
Originally Posted by rleete View Post
Your alternator may be rated at 70 amps, but not for long. That's peak, and only for short bursts. Otherwise you'll melt the windings.

4 gauge is plenty for automotive applications.
how bout starting the car? i ran 2ga to the trunk when i relocated the battery to the trunk in my s13, and still seems to crank more sluggishly than the stock setup
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Old 04-10-2010, 01:03 AM   #16
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Btw, what is a cheap online source for a good automotive grade wires? Including shielded one for sensor signals, etc.
Kinda like Monoprice.com but for automotive wire



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Old 04-10-2010, 01:40 AM   #17
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Quote:
Originally Posted by Mach929 View Post
how bout starting the car? i ran 2ga to the trunk when i relocated the battery to the trunk in my s13, and still seems to crank more sluggishly than the stock setup
Where was your Ground connected?
(G)
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Old 04-10-2010, 02:36 AM   #18
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Check out waytechwire.com, under GPT primary wire. It is great stuff, full automotive grade coating, and not much $$. We use it on our FSAE car and love it.


EDIT: look under SGT or SGX for battery cable


Quote:
Originally Posted by j_man View Post
Btw, what is a cheap online source for a good automotive grade wires? Including shielded one for sensor signals, etc.
Kinda like Monoprice.com but for automotive wire


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Old 04-11-2010, 04:13 PM   #19
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Originally Posted by Reverend Greg View Post
Where was your Ground connected?
(G)
i still have the one up front doing engine to chassis. and i added one in the back from battery to chassis
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Old 04-15-2010, 01:45 AM   #20
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Quote:
Originally Posted by cardriverx View Post
Check out waytechwire.com, under GPT primary wire. It is great stuff, full automotive grade coating, and not much $$. We use it on our FSAE car and love it.


EDIT: look under SGT or SGX for battery cable
Looks like this is the correct link (k instead of ch):

http://www.waytekwire.com

Thanks!
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