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

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......Hi all, I'm going to re-locate the battery in my '32 Ford to the trunk. Right now it's behind the seat. Plus the cables currently run inside the car & I read in a recent post on the site that it's better to have them outside mounted on the frame. So this is what I'm going to do. But, I'm not sure on what size cable to use. I saw a kit on Jeg's that used #1 cable, Is this big enough???? THANKS Bill

i use welding cable size O

....THANKS Pat, well, I called a couple of local auto parts r/e; I need some battery cable that I can cut to length that I need. No one seemed to have it. THIS solves that problem!!! I'll just go to a Welding Supply Store!!!!! Thanks again, Bill

I use 1/0, and get it at a marine supply store. The sell it by the foot, as well as the appropriate ends.

Don

Originally Posted by Itoldyouso

I use 1/0, and get it at a marine supply store. The sell it by the foot, as well as the appropriate ends.

Don

.....Thanks Don, I checked with West Marine & the 1/0 gauge battery cable is $13.69 a foot! Does this sound right? I'm putting my battery in a sealed box in the trunk plus installing a Flaming River cut off switch. So I figure I'll need about 11 feet of cable which comes to $150 + tax. Is this cable that much better than regular automotive cable? It sounded like it was way more durable & resistant to the elements than the auto cable. So I'll go for it if it makes a difference.... What's your opinion? Thanks again, Bill

I worked for West Marine for years, and ever since they bought out Boat U/S, they evidently feel they have no competition, so the sky is the limit. Their prices have all gotten ridiculous IMO.

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

Originally Posted by billlsbird

....THANKS Pat, well, I called a couple of local auto parts r/e; I need some battery cable that I can cut to length that I need. No one seemed to have it. THIS solves that problem!!! I'll just go to a Welding Supply Store!!!!! Thanks again, Bill

While you're there, also purchase the lugs to terminate the cables. In my opinion, welding cable is the best there is for long runs on autos. If you do the research, you'll find that it uses quite a bit more strands of a smaller size and is more flexible than the same gauge automotive-type cable available at parts stores. I'm a good customer at Phoenix Welding Supply.

I've never used marine cable like suggested by Don, so I cannot compare it. But if Don has used it and approves it, that's good enough for me.

So you guys would frown on a kit like this...?
http://cgi.ebay.com/ebaymotors/Unive...WDVWQQtcZphoto

Originally Posted by Gusaroo

So you guys would frown on a kit like this...?
http://cgi.ebay.com/ebaymotors/Unive...WDVWQQtcZphoto

No, those are defenitly nice if there is a tight budget...Or if you are just doing it to move some weight around your 32 Ford and not really worried about "REALLY" good voltage system ,there fine.

just go to a welding shop. they will have short lengths . they cannot use cable that has a tear, because it might short to a steel plate they are working on. Copper is about 2.50 a pound now, so expect to pay about a 1.50 a foot for the used.

I used the welding wire and I am very pleased, it's tough as nails and reasonably priced. My records said I paid $3.65 pft for it 3 years ago.

1/2" solid copper bussbar would probably be cheaper.

BUT that would come with its own problems...

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

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