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spkrman wrote:If the path of least resistance is all around the car, that increases path length at the same time.

I actually performed a sort of a "test" where I used my old frame ground with upgraded ground up front with just my rear battery to start the car. It was *much* harder to start than with just the 2/0ga wire up front for ground.

The best way was with both connected :)

Ok so if its all around the car that increases the path length.

But adding a wire AND using the car does not?

That should show you your logic on this issue is flawed...

Path length has nothing to do with it. It will flow from one contact point to the next by the route of less resistance.

It has been long known the best areas for grounds are on or by the subframes as they will conduct more electric. Also because of design they are superior for grounding spots.

Basstronics wrote:Ok so if its all around the car that increases the path length.

But adding a wire AND using the car does not?

That should show you your logic on this issue is flawed...

Path length has nothing to do with it. It will flow from one contact point to the next by the route of less resistance.

It has been long known the best areas for grounds are on or by the subframes as they will conduct more electric. Also because of design they are superior for grounding spots.

I'm not going to argue this with you, its pointless.

If you want to test it, I invite you to please give it a shot.. try to start your car on a weakish battery thats grounded however you want in the rear. Note how much harder it is than having that same weakish battery up front...

Now try to crank with a run of 1/0ga wire for your ground up front, much better eh?

Of course, thats impossible in your eyes, although you've never tested it.

I suppose most DBdraggers use multiple runs of + and - wire to their rear amps in the street classes because they enjoy the purty colors?

Depending on your car and your wire routing, using the wire WILL decrease your path length as opposed to even the best frame ground.

well for what its worth we have always grounded in the rear but usually upgrade the factory ground up front as well. minimum 4 guage wire up front to improve upon the factory ground.

Maybe Im taking your post to literal?

In the same post you say:

"If the path of least resistance is all around the car, that increases path length at the same time."

Then you go onto say:

"The best way was with both connected"

Which reads to me as you are using the normal grounding method *and* a wire from the negatvie of the battery to the back where the amps are grounded.

If this is so your argument of path length is flawed. That is all.

i didnt say path length was the reason body grounds aren't good enough - the frame/body itself on most cars isn't good enough.

The best way was using a rear frame ground AND a wire running up front... I assume because that gives the car a solid ground (for all the accesories and stuff grounded to the body) + gives plenty of current for the starter and such up front.

and of course, more is better :)

smoker wrote:well for what its worth we have always grounded in the rear but usually upgrade the factory ground up front as well. minimum 4 guage wire up front to improve upon the factory ground.

have you ever done a very high power setup?

once you get some real juice goin body ground just doesnt do it.

on an average car, a chassis ground is considered equivelant to a 4AWG cable.
This will vary from car to car though. In my case, it's probably a bit better, being all 1966 Detroit steel, and no rust. Modern cars are usually unibody or floating frame though, and a lot of fiberglass, relying on spot welds for most sectional joining. That's not an ideal connection as spkrman mentioned, unless you're reinforcing the frame and joining front and rear halves with frame connecting beams etc.. common to do on Fox body mustangs to stiffen the frame etc, but not a common thing for the average Joe to do.
If you're drawing thousands of watts of power, and using one or more runs of 0AWG of larger cable, it's worth considering running ground back to the battery or to the engine block ground point instead of relying on a bolt in teh trunk.
If youw ant to be sure, you can measure resistance to see what you're dealing with for a specific application.

I guess it does vary by car, but I thought I read somewhere(RC I think) that a typical chassis ground was equivalent to 1/0 gauge. I always wanted to measue the chaasis resistance of my Explorer, but was wondering how you would do that. I guess you'd have to measure the resistance of your extra long probe leads and subtract that from the value you got. I thought of using an analog meter and zeroing it with the leads intact, but they kinda suck when it comes to measuring very low resistances(not enough resolution on the gauge).

I really wasn't saying that a 2/0 ground cable wouldn't be better, but I don't think chassis grounds are as sucky as everyone thinks.

-Fishy

Well I've come to the conclusion that my multimeter is completely useless for measuring chassis resistance. Its a $50 Micronta and does not like anything under 1 ohm. Are those expensive Fluke deals any better at measuring resistances on the order of milliohms?

I can't vouch for the numbers, but it looks as though my Explorer's chassis resistance is about the same as a 20 ft piece of 1/0 gauge. In other words the reading I got using that 1/0 was as probe wire was about twice what the 1/0 itself measured.

-Fishy

Fishy wrote:Well I've come to the conclusion that my multimeter is completely useless for measuring chassis resistance. Its a $50 Micronta and does not like anything under 1 ohm. Are those expensive Fluke deals any better at measuring resistances on the order of milliohms?

I count vouch for the numbers, but it looks as though my Explorer's chassis resistance is about the same as a 20 ft piece of 1/0 gauge. In other words the reading I got using that 1/0 was as probe wire was about twice what the 1/0 itself measured.

-Fishy

I put in there that I was using 2/0ga wire didnt i?

I'm not certain how 1/0ga would react.