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Discussion Starter · #1 ·
Try to follow this. The main power feed is from a wire coming from the + battery cable where it attaches to the battery. Im using a Ford solenoid and have the battery cable going from the + battery terminal to the solenoid. My Question is can I change the location of the main power feed from where it now to where the + cable bolts to the selonoid? Would it nrealy make any diffrence?
 

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Good question. Guess it would depend on the size of the main + battery cable. You would be adding additional current demands on this cable and could experience a voltage drop across it during cranking. This would cause reduced voltage to everything else, including ignition, while cranking. Again it would depend on the size of the main cable. Can it handle the additional load added to it by moving the other positive wire?
 

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Is this what you want to know?

Yes you can pull power from where the battery is connected to the solenoid,instead of off the battery post itself.

If he is using a fold solenoid then he probly has a big guage wire from the battery to the solenoid becuase thats what feeds power to the starter.
 

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Originally posted by supersport396_2000:
Is this what you want to know?

Yes you can pull power from where the battery is connected to the solenoid,instead of off the battery post itself.

If he is using a fold solenoid then he probly has a big guage wire from the battery to the solenoid becuase thats what feeds power to the starter.
Whether he is using a Ford soleniod or the regular GM one on the starter he has a big cable going to it to supply power to the starter, I realize that. Not all battery cables are the same size though and moving the other wire, which is not all that small, probably 8 or 10 gauge, just puts more load on the main cable. I'm not saying it won't work, in fact it probably will, I'm just not going to guarantee it. Not without knowing the wire sizes and current draw of his starter.
 

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Discussion Starter · #5 ·
Well the + cable going from the battery to the solenoid is a 1 gauge witch is about 12" long. The main power supply comes off the wire at the battery post and is only about a 12 gauge if that. I want to upgrade it to a 8 gauge and want to know if it makes a differance which end of the cable I attach it to. Does it make sence now?
 

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Originally posted by Herb:
It would be very unusual to experice any significant voltage drop (>.2v) across 12 inches of 1 gauge stranded copper cable at 12v if the connections are clean and solid.

You should be fine.
If Herb says it will work it will work. Seriously, I'll go with Herb on this one. I've seen some pretty small gauge and rather long battery cables used in some setups, without details it was pretty hard to answer.
 

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But won't the amount of voltage drop depend on the total load of the circuit, including the starter engaged? Or am I missing something??
 

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Originally posted by wayner:
But won't the amount of voltage drop depend on the total load of the circuit, including the starter engaged? Or am I missing something??
You are correct. The voltage drop across the wire is dependant on the total current, actually what the total resistance of the circuit is vs. what portion of that total resistance the wire represents. The bigger the wire the less the resistance. The shorter the wire the less the resistance. Given that he is using a 1 ft long 1 gauge wire it is hard to see were it could offer much resistance in the given circuit.

I hope I explained that so it makes sense.
 

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Thanks Hank, But if a starter is dragging and drawing excessive current there maybe a voltage drop regardless of the wire resistence?
 

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Originally posted by wayner:
Thanks Hank, But if a starter is dragging and drawing excessive current there maybe a voltage drop regardless of the wire resistence?
Yes sir, right again. No matter what size wire or it's length it can happen. Now consider this, the 1 gauge 1 ft wire is virtually 0 ohm's, no resistance, not really but close enough. It's not until the starter shorts internally and approaches 0 ohms, no resistance, that the wire becomes a factor. As long as the starter has some resistance the amount represented by the wire is small in comparison. Example, no bearing on this situation just easy numbers to use for an example.
The starter has a resistance of 1 ohm. The wire has a resistance of .01 ohms. That’s a 100 to 1 ratio. Since the total current drop is always 12v all you have to do is divide it up between the 2 parts. The wire will drop ~ .12v and the starter will drop ~ 11.88v.

So let’s say the starter shorts, now the wire becomes a factor. At this point it doesn’t make much difference if that other wire is at one end of the big battery cable or the other. The amount of load it adds is insignificant compared to the shorted starter.

Again I hope may explanation was understandable. I understand it but I make a losey teacher.
 

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Thanks Hank, for taking the time to explain it!
 

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just move the cable, it will be no problem, if the starter drags, it will fire any cable regardless of wire size, but more likely to fire the solenoid first.
 

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Originally posted by Finally:
So let’s say the starter shorts, now the wire becomes a factor. At this point it doesn’t make much difference if that other wire is at one end of the big battery cable or the other. The amount of load it adds is insignificant compared to the shorted starter.
I guess you guys got tired of my long winded response and didn't read to the end. I already said exactly what engineer and Herb just stated.
 

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What kinda of meds you got available Herb? I might be interested. :D As far as the fire and melting wires, yea I guess I didn't come right out and say it. Just said if the starter shorts that other wire is the least of your concerns. Well that wire and the little braided ground straps of course. ;)
 
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