[AT] Tractor wiring

Phil Auten pga2 at hot1.net
Thu Nov 18 17:30:35 PST 2004


It's the current capacity of the wire that determines the gauge needed. 
More current, bigger wire. It's that simple.
The bigger wire has less resistance so it "drops" less voltage over it's 
length. A 4 Ga. wire might drop 2V over a 4
foot length at the current drawn on a 6V starter. Changing to a 0 Ga. wire 
will decrease the dropped voltage to less
than 1V. More voltage applied to the starter so it can get the full current 
needed to spin it and the engine up to
starting speed.
Another analogy is pipe and water flow. A 1/2" pipe can only flow X amount 
of water at 25 PSI. If you double the
size of the pipe, you get more flow at 25 PSI.

Phil

At 08:51 PM 11/17/04, you wrote:
>Here is my question on this subject.
>
>Why are battery cables for 6 volt systems heavier than those for 12 volt 
>applications?   Assuming both are powering a starter to turn a similar 
>size engine (similar load), why would the 6 volt cable need to be 
>bigger.  It flows more amps but less voltage and should flow roughly the 
>same wattage in both applications.
>
>Charlie





More information about the AT mailing list