[Vwdiesel] Relocating battery
Area31 Research Facility
stephensrw at stn.net
Mon Jan 1 19:56:22 EST 2007
Loren, All,
In a DC circuit the entire cross section of the copper conductor is carrying
current. The phenomenon you speak of where the current hugs the surface is
called skin effect and is only an occurence in AC circuits. At 60 Hz, skin
effect is negligible. It starts to be an issue at 10 KHz or more depending
on the circuit.
Fine stranded welding cable of a particular gauge size will carry the exact
amount of DC current with the same loss as any other cable of the same gauge
size (solid cross section) if it is solid bar or just a few thicker
conductors bundled together, provided they are all made of identical metal,
say copper.
You do NOT automatically get more loss with DC than AC. Loss in a wire is a
function of the resistance, nothing else, until you get up to high AC
frequencies where inductance and skin effect can have a role.
Rob
----- Original Message -----
From: <LBaird119 at aol.com>
To: <vwdiesel at vwfans.com>
Sent: Monday, January 01, 2007 7:14 PM
Subject: Re: [Vwdiesel] Relocating battery
> In a message dated 1/1/2007 1:36:41 PM Pacific Standard Time,
> MikeyBigFish at wmconnect.com writes:
>
>> Not having any fundamental/basic understanding of electricity is the
>> hat that fits my head, but it serves well as a good cover.
>> So I ask my beloved forum, is it possible/feasiable to physically coil
>> this cable to increase or stabilize the desired battery cranking
>> speed?
>>
>
> I've been going through similar arguments with Dad on his solar
> project. Loss is loss and the longer you run a wire the more loss.
> More loss on DC than AC, the lower the voltage the higher the loss,
> with DC anyway, and the higher the draw the bigger wire needed. Coiling
> wire would make the wire longer. I suppose creating some back emf or
> such but that would only serve to cut the amount of power run through
> the wire rather than the amount available at the other end... At least I
> think so.
> Simply use as big or one size bigger than needed and there you go.
> I've been trying to convince Dad it's not worth cutting up a welding lead
> of the same size as some wire he has, simply to have the finer wire.
> (since electrons travel on the outside of the conductor I suppose it
> should
> carry more current but how much really?)
> Loren
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