Anyone have any insight. I have heard many thoughts on this, and was thinking since the frame can pick up alot of interference, wouldn't running the ground straight back to the battery terminal (factory ground) yield a stronger ground? I know some that do it, and PPI amp's manuals recommend it. So my question is, if space and money (for wiring) weren't an issue, would this be the best solution?

 

Thats a pretty long wire
Dont you want your ground to be as short and close to the amp as possible!

 

I also believe there is a benefit to grounding back to the battery. But wouldn't do it for less than a couple thousand watts or a system with no extra processors outside the headunit. But I can't give a scientific explanation. I plan to do it, but only if the funds become available. Wireing will have to be equal thickness as the positive wireing. I currently have a single 1/0 power wire. But intend to upgrade to a pair of 1/0's soon. So that will be a total of four 1/0 wires to cram someplace and wire back to the trunk. I may run the ground wire under the car and the positive inside the cabin.

There is a slim chance the system I am designing will not be as powerful as I originally thought. Because the sub setup will be very efficient I might only need one class D amp for both subs to share. That would drop my current requirement by 120 amps. And there is one other amp I might use for midbass that is a little more efficient than conventional AB amps. But no matter what the power to my front stage will be significantly greater than my old set up. Possibly about 800 - 900 watts RMS per channel. So if I do find a way to install a center channel without robbing a bank, I will most likely have a pair of 1/0's.

 

This is what I heard....Copper wire has less resistance than steel body frame.

 

It's a matter of decideing if the difference is measureable. With nearly 2000 watts in the system I just took out it was not measurable with my ears. Or with my DMM. But the new system I have pretty much decided on the power will be significantly higher. And the number of processors and other accessories will be greater. All these acceessories add their own noise and draw current. Resistance through steal may be greater than through copper. But I can't afford to replace my steel frame with one made of copper. And the structuaral losses of switching would definitely be felt. Are a couple 1/0 gauge copper cables thick enough to cunduct as efficiently as a steel frame and body? That's the real question.

 

 

I think a proper frame ground would be much better.. I would like to see what the resistance is through ~17' of frame though.. I bet it's lower than 17' of 1/0 though..

if you were going to go to the trouble of doing this though, go to the alternator, not the battery.. same with the power cable..

 

Well the frame itself is open to everything; the elements and any other things that can hinder it's performance. Not to mention, it would eliminate that damn electrical shock some cars give off when you get out of the car and touch the doors.

It would be nice if someone did a before and after test or something that could clear this all up. Check resistance, voltage drop, etc. and find out.

And about grounding right back the the alternator, rather then the battery.... Wouldn't that cause me to lose that extra cushion of current that the battery provides when the alternator can't push anymore?

 

Sorry Audio, but I don't think that will fix your shock problem. That problem is usually caused by you not the car. When you get out and slide your butt on the seat you build up a small static charge (similar to scuffing your feet on the carpet in your house). When you touch the metal door. The charge is released.

As far as your original question, I would agree somewhat with TL but not for the same reason. Firstly, I would say the frame of the car has a much larger resistance than a same length of copper wire. The real issue is which would pick up a larger amount of stray signals. Do to the way that electric/magnetic fields operate, I would guess that a long straight wire would be more apt to pick up signals. For this reason, I would keep the ground wire as short as possible and connect to the car frame. Plus this method is a lot simplier/cheeper. Either way though, I think in most cases the differences are negligable and certainly not audible.

Brett

 

We don't want to ground to the alt for two reasons I can think of. The first is noise. Alternators are real noisy in the electrical domain. I don't know if it's simple A/C noise from the way they generate electricity or it it is more complex. The battery only allows the DC voltage to pass through and cleans up a lot of the noise. The second would be as mentioned above about the battery supplying voltage both at low RPM's and when the system is really turned up beyond the current limit of the alt.

Anyone have the Dec 02 issue of Import Tuner? The one with the Skyline somewhere on the cover. Go to page 76 where they actually tested the Hyper Ground System from Sun Auto. I was shocked that the test results actually showed measurable improvement. Even in a Maxima with ignition coils in the cylinder heads. The cars they tested gained an average of 1.03 to 7.09 hp. The Max gained 2.1 horses at 2000 rpm, up to 11.6 at 4500 rpm, and back down to 7.0 at 6000 rpm. The ground wire they use connects in series across many points. And they had to test many different ground points to determine which were the best for improvements.

http://importtuner.com/toc/

Unfortunately that article is only listed in the contents. It's not online. They also included no pics of how / where they connected it in the maxima. Maybe if we all email for specific someone will get lucky and get a real answer.

importtuner@mcmullenargus.com

But the biggest thing about these wires that makes them stand out is probably the shielding. They are either double or triple shielded. And that is what would make it tough to duplicate without spending more money than what it costs to purchase this system. But I am hoping our moderator or another EE will help us out with this. I recently got the new parts express catalog and they have some mylar shielding - http://www.partsexpress.com/pe/pshow...number=082-428
They also have smaller diameters. This may be good for both power and ground wires. Hopefully a EE or someone else with electrical knowledge will read this.

 

i think regardless if you run the ground back to the battery, you must ground, as short as possible, from your amp to some point on the chasis.

 

<-- not an EE But I just looked up the resistivity of steel.. I think I agree now.. granted the x-sectional area is much much greater in the frame, the resistivity is on the order of 23.5 times higher..

it would definately be interesting to see some measurements

 

Did you find it online or do you have it in print? I've been lookng around for the differences in resistance betweeen materials for a while now. Could you list the primary metals and the multipliers? Aluminum, steel, brass, copper, titanium, etc.

 

I'm not sure if you have space, but it would make things easier if you just relocated your battery. Your system would have a short, direct route to battery power and ground, and you would just have to run cables for the battery relocation.

You could also build some sort of custom enclosure if you so desired.
-hype

 

Let's see, another 72 lbs for the battery, in the trunk. No, don't think so. Besides that is the space to mount the battery. Nope, not in my iddy bitty trunk. Unless I somehow get the dough for a turbo, then the battery would have to move anyway.

Don't forget that if you put the battery in the trunk you have to run 1/0 to the alternator. Overall I believe the battery under the hood is easier.

I finally made it to a welding shop today. $3.23 per foot for 4/0 stranded copper wire. And they can fabricate a ring terminal to attach to the battery post. At that price it may not be too bad to use a cable for positive and a cable for negative. The hard part will be fusing 4/0 cable up close to the battery. They did not have any heavy duty fuses and waterproof fuse holders at the welding shop.

 

i think you can not base decisions purely on the resistivity of a material. you also have to take into consideration other conditions, like surface area.

i'm in senior standing majoring in comp. engineering, almost the same as EE.

 

Sorry, I've been looking for resistance of various metals for other reasons as well. So I still want that info.

The surface area of the car frame is the primary reason I think I might go ahead and run a ground wire back to the trunk. The car frame can absorb noise from everywhere. It's like a big magnet sucking in noise from everywhere so that our power amps can magnify it 10,000,000,000 times. Okay, maybe I exagerate. But I think you know what I mean even though I don't know how to accurately say it.

 

I'm a EE (well I'm a senior in EE). I'll stick with what I said before.

"As far as your original question, I would agree somewhat with TL but not for the same reason. Firstly, I would say the frame of the car has a much larger resistance than a same length of copper wire. The real issue is which would pick up a larger amount of stray signals. Do to the way that electric/magnetic fields operate, I would guess that a long straight wire would be more apt to pick up signals. For this reason, I would keep the ground wire as short as possible and connect to the car frame. Plus this method is a lot simplier/cheeper. Either way though, I think in most cases the differences are negligable and certainly not audible."

To this I will add that the grounding back to the battery might be better if you could reduce the noise. There are devices that can help in this but not without adding significant cost. Doing some quick and dirty calculations, I find that for any cable length under about 20ft, the difference will probably be negligable (but shorter is always better). So in the end, like I said before, I doubt it makes any noticible difference.

Brett

 

Ahhh, okay. But, I think I will check with at least one other source before I decide to go either way.

 

I found it online.. http://www.physics.gla.ac.uk/~dland/E1A/tsld023.htm

short list, but I didn't have to go any deeper for this thread