Thread: what size battery cable should I run???

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Originally Posted by Itoldyouso

I just phoned a local marine store, the Marine Trading Post, and their price is $6.50 a foot. That is the kind of store you are looking for. Most larger cities have these kinds of places. West Marine and Boaters World have become places that only want to sell stuff in prepackaged boxes, and who do not mind marking stuff up significantly.

Don

.....Don, well after calling numerous Boat Supply places in my area I did a search for 'Marine Trading Post' in your city, Florida. Yep, the place came up & I was just about ready to call them to order {free shipping for all orders over $100 dollars!}. But then I found one more place & they had the 1/0 for $8.60 a foot. I figured this was close enough so I got 12 feet of it {Marine grade cables}, two battery terminal ends, 5 'other type' ends {the ends that'll go on the starter & the Flaming River cut off switch}, a cool little 'gizmo' that crimps the end of the battery terminal ends & some rubber shrink stuff to insulate the ends....

THANKS Everyone for all your help! Bill

Originally Posted by skids72

I would stay away from the solid copper... current flows more along the surface of the "wire" especially high frequencies (spark draw). With a solid bar the total surface area of the "skin-depth" is small compared to stranded wire (each strand carries the same "skin-depth" area). Full disclosure, I'm using #1 automotive wire but it's been recommended to me locally to use 2/0 welding cable for it's lower resistance and more importantly, it's flexibility makes it easier to work with. My wiring is a mess and I may go this route at the end of the season...

Two cents,

Chris

This would only be of concern in AC (60 Hz and higher) or transient DC circuits (pulsed alternators or railguns for example) and not really applicable to automotive DC circuits at all. "Skin Depth" is proportional to 1 over the square root of the product of pi, electrical frequency, conductivity, and permeability. Essentially in a DC circuit the electrical frequency is 0 and thus the skin depth tends towards infinity. Any electrical transients resulting in temporary skin effects are not of concern in automotive applications.

Check out the 1/0 Taylor welding/battery cables. IMO they are the best ..........

Kitz

Thanks for keeping me honest Dr. Kitz. Although I might argue that current draw in an automobile does have a high frequency component particularly related to the ignition system which will be comprised of a fundamental and harmonics of say 800Hz for an 8 cylinder engine at 6000rpm. I think for these components of the electrical load, the skin depth will be on the order of <100um given copper conductivity of about 17 nOhm*m and permeability of about 1.3 uN/A^2. I'm probably missing something here and I certainly don't intend to impugn your judgement and must defer to your doctorate compared to my lowly BSEE (emphasis on BS )...

Am I thinking about this incorrectly?

Thanks,

Chris