I was thinking about my wiring set up today. In my new vehicle I have yet to do the Big 3, but I do have a dedicated 1/0 ground wire that goes from my back battery to my front. Is it really necessary to do the big 3 if you have a dedicated ground? I can see the upgrade being useful if you are using a chassis ground because your return path would be limited to the chassis to battery, but if that is elimated is there still a benefit?

As far as resistance for the power wire goes, lets say the wire from the alternator to the battery is 4 feet. The stock wiring is 8 awg, which in general has a resistance of 2.061 ohms/km. This means the resistance of the wire is 0.00251 ohms. 1/0 awg has a resistance of 0.3224 ohms/km, so the resistance is .00039 ohms. It would seem that the benefit of switching this wire out is lost at this point.

I have considered switching my dedicated ground to a second power run and then doing the big 3, but I'm not sure if I need to yet.

I'm just wondering what your opinions are, and whether I'm looking at this the wrong way.

So if I understand correctly your battery is in the trunk, and it has 0 gauge going from it to the alt? Where is the battery grounded?

You are looking at it the wrong way. Calculate voltage drop vs current then you will see the benefit.

So if I understand correctly your battery is in the trunk, and it has 0 gauge going from it to the alt? Where is the battery grounded?

No, I should have explained this better. I have a front battery with the stock connections. I have a battery in the rear with 1/0 run on both the positive and ground runs to the front.

The long run cables to the rear is to help keep the voltage up for your alternator.

If that ground cable you have ran from rear to front attaches to your front battery, then it would be wise of you to run an extra power AND ground cable from the alt to the front battery.

The front battery itself doesn't need an extra ground on it.

This will help keep the voltage high from the alt to the front battery since your rear battery has been decided to attach to the front battery.

The long run cables to the rear is to help keep the voltage up for your alternator.

If that ground cable you have ran from rear to front attaches to your front battery, then it would be wise of you to run an extra power AND ground cable from the alt to the front battery.

The front battery itself doesn't need an extra ground on it.

This will help keep the voltage high from the alt to the front battery since your rear battery has been decided to attach to the front battery.

Ok, so what you are recommending is basically upgrading the alternator's circuitry to the front battery because the long ground run eliminates the need for an upgraded chasiss ground. How much would an upgrade from a stock 120 amp max alt really affect the stability of voltage? See what I calculated in my next reply, I'm not sure if I did it right.

You are looking at it the wrong way. Calculate voltage drop vs current then you will see the benefit.

Well I decided to use the NEM standard to make it easier so this is what I came up with.

V = I*R

1/0 awg, V = 120 amps (max rating) x ((4 feet x .0983 constant)/1000) = .047v or 0.3% drop (assuming 14.4v), 1.8 micro amps are lost in transmission

8 awg, V = 120 amps (max rating) x ((4 feet x .6282 constant)/1000) = .30v or 2% drop (assuming 14.4v), 753 micro amps are lost in transmission

Looking at it this way, even at the max end of the spectrum which I know my stock alt will never reach, I don't see a major benefit. I suppose when I think of a .3 v drop vs .047 v it has it's benefit but I'm not sure if its worth the cost.

Let me know if I'm still on the wrong track.

Edited September 15, 201212 yr by ulrisa

Stop being technical...

What about resistance in terminal?

Did u perfectly crimp it?

Heat inside engine bay lowers current flow of wire.

What about resistance in material u are connecting terminals too?

I see what you are saying. So I guess from a technical standpoint it's not really worth it, but in real world all of those extra little resistances will make it worth it. Good to know, I was going to upgrade at some point eventually but I was just curious to see what you guys were thinking.

Dont replace, just add to it. You mention replacing your stock 4 gauge. Just add a run of 1/0 to what you already have.

I know what you are saying, which I would go that path when I upgrade. My main question was whether it was beneficial or not to do when you have a dedicated ground cable vs chassis ground. I've come to the conclusion that in this scenario it is still benefical to upgrade the alternator's wiring.

Yeah I think you're just overthinking it. Just do your big 3 and get it outta the way, it's such a small amount of wire it's not like it's really costing you that much to do it.

Are you coming to Sanford on the 29th?

Edited September 16, 201212 yr by Kangaroux

Yeah I think you're just overthinking it. Just do your big 3 and get it outta the way, it's such a small amount of wire it's not like it's really costing you that much to do it.

Are you coming to Sanford on the 29th?

Oohh I didn't know there was a show on the 29th. I will try my best to get down there, I haven't had much time lately. I'm getting my ZCON 18 in this week though .

Yeah I think you're just overthinking it. Just do your big 3 and get it outta the way, it's such a small amount of wire it's not like it's really costing you that much to do it.

Are you coming to Sanford on the 29th?

Oohh I didn't know there was a show on the 29th. I will try my best to get down there, I haven't had much time lately. I'm getting my ZCON 18 in this week though .

Ah shit I wanna hear that. I almost got a zcon 18 but I didn't have the cash for it and had to settle for the xcon. Not like that's a bad thing, though lol.