[AT] Tractor wiring

Phil Auten pga2 at hot1.net
Fri Nov 19 15:57:37 PST 2004


Note that I used the water pipe as an analogy, not a direct transfer of 
capacity. A 6V cable doesen't need to be any bigger to flow the same 
current as a 12V cable, but since we are talking about starting circuits, 
the current will be more, most likely close to double, than the 12V 
starting circuit. If the 12V starter draws 100 Amps, it stands to reason 
that the 6V starter will draw 200 Amps for the same wattage. I don't know 
for sure what size cable would be required for the 200 Amps since I can't 
find my design guide right now (gotta find that to send a copy to Greg 
Haas). I'll bet that a 4 Ga. wire won't do it as well as a 2 Ga. :o)

Phil

At 07:25 AM 11/19/04, you wrote:
>Phil,  a 1 inch pipe will flow 4 times as much water at a given presure 
>than a 1/2 inch pipe ( if you assume laminar flow).  Does that hold true 
>with wire size or is the difference smaller?   Does the cable for a 6 v 
>battery need to be twice the diameter of that for a 12 v or ?
>
>Charlie
>----- Original Message ----- From: "Phil Auten" <pga2 at hot1.net>
>To: "Antique tractor email discussion group" <at at lists.antique-tractor.com>
>Sent: Thursday, November 18, 2004 8:30 PM
>Subject: Re: [AT] Tractor wiring
>
>
>>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





More information about the AT mailing list