Alot of people are talking about running a ground wire directly to the battery of the car. I know that this is not a good idea but could not give a logical reason for it not being a good idea. I found this Q&A on Rockfords website this morning. Has anyone else found anything to support this or rebute it?

The preferred method for grounding an amplifier would be to keep the ground wire as short as possible (assuming the vehicle allows this), and connect it to a clean bare metal point on the vehicle. Running the ground wire to the battery actually increases the chances for system noise, and can cause more grief than you'd expect.
Question:"Do I have to run the amplifier ground wire to the battery as well?"

Answer:"The recommended way to ground your amplifiers is to keep your ground cable less than 18" long, the same exact size/gauge as the power cable, bolted directly to a solid, thick steel part of the chassis which is scraped and polished clean of any paint or primer for best possible grounding."
Courtesy of RF technichal

 

There are two things (at least) to consider when grounding amplifiers, or any other audio equipment for that matter.

1) The ground conductor's (whether it be a wire or the chassis of the vehicle) ability to carry the current passing through it. The ground conductor should be the at least same size/gauge as the power lead; it is the "return path" in the system and sees the same current as the power lead.

2) The conductor's potential. By potential I am referring to it's voltage state, with ground equalling "zero". IMO, RF's statement Running the ground wire to the battery actually increases the chances for system noise... assumes that the vehicle's chassis represents an ideal zero voltage condition, which it should, and that all other components be similarly grounded.

Probably the biggest cause of system noise is when power amplifiers are used and multiple components are grounded to different locations of differing ground/voltage potentials (i.e. <tenths of a volt of differences). This is when you will hear whining, "alternator" noise amplified through your system.

Therefore, grounding an amplifier to the chassis may yield the best current carrying capacity (assuming the connection from the negative battery terminal to the chassis, and any other metal-to-metal connections are clean and solid), but system noise could still be introduced if other components are not also "well-grounded", or if there is some "dirty" spot in the chassis ground path.

I have done systems both ways. I don't personally feel one method is better than the other, as both have pros and cons. RF's method may be the easiest to get right for some people/vehicles and may be a good starting point.

FYI, in my current system, I AM runnning all power and ground wires for all components directly to the battery.

 

Well, all I can say is that the only completely noise free install that I have ever done was my only system where I ran the ground back to the battery. There was ZERO noise in that install. From here on out, I will be grounding back to the battery. Just my experience. :cheers:

 

But on that note how did you test for noise? The only true way to test is to use a zero bit cd and turn the volumne all the way up. I have never ever run the ground to the battery and have done well over a thousand system installs noise free. But that is not the reason I made this is post. Valuable as our opions are I was trying to find a more technical factual reasons for either going to the battery or not.

One thing I was thinking about going to the battery. When you do install like that do you compensate the gauge of wire for the added distance? When you ground a component to the chasis you are now using the entire chasis to supply current to that component. And we all know that a power wire is only capable of conducting so much current over so much distance. Lets say that there is an amplifier that needs 50 amps to perform to its peak and it is 15ft from the battery. According to IASCA (IASCA under rates the wire but this is good source for this hypathetical situation) a 4ga wire would be needed to run to the amp. Since the current path is now going to be 30' long shouldn't a 0ga wire be used instead? Not trying to put anyone down just trying to figure out a logical technical answer to this.

 

I dropped the ground cable down behind the seat and used the bolt that holds down the passenger seat. No noise here.

By the way, after my visit to the Corvette museum, drilling into that panel behind the seats would NOT be a good idea, there's a fuel tank there. I mounted my video interface unit on that panel :eek: :eek: Lucky I didn't hit the tank.

 

My experience, for what its worth: On a previous vehicle I tried to make a "super clean" install and removed my short ground and tried to put in a 4 gauge wire going back to the battery. Prior to moving the ground (Short length to the chassis) there was no noise as tested with the Alpine audio test Cd that I had. After I ran the heavy gauge wire to the battery there was significant "engine whine" noise at all volume levels. The car was a 1989 Trans Am GTA Vert.
I have since always used a short ground and have had zero problems.
:flag

 

Hi Randy,
I go both ways on this one (no flames you sicko's :smash: ).
Currently the only car I run the ground back to the battery is the vettes, the other three use short grounds. The vette was done this way due to the uniqueness of the way the car was built (fiberglass, alumimun).

The double length of wire is not exactly true. It is a very common misconception. The frame of the car is a "wire too". The car is not a ground til you hook up the neg terminal of the battery to the frame and/or engine block. The "true" ground is therefor is the neg post of the battery. If you don't beleive me, try running your stereo with the negitive of the battery not hooked up. In fact, when you install any equipment in your car what is one of the first lines in the instructions: Please disconnect the NEGATiVE lead on the battery.
As for the guage chart, I don't use it anymore. I will put in what I can afford, 0-guage in the case of the vette.
Clear as mud :confused: :yesnod:

 

That is true about the car being the ground but you have to think of the car being one HUGE ground wire. Now I understand about the Corvette due to it's build but Iwould think still have to take into consideration the wire gauge on both ways positive and negative.


hehehehe you said you go both ways :lolg:

 

you bastage :bb
Yep, you said it. A huge ground WIRE that could handle 100,000 amps :confused: A chain is only as strong as it's weakest link. In your case that weakest link would be the positive wire. In my vette pwr system, the links in my chain are of equal strenght.

Hope you are having a Happy Thanksgiving! :cheers:
I have to go to work soon :banghead:

 

Happy Thanksgiving to you too. You have to work? That is too bad.

 

Not the "where do I ground my amps" thread again! :lol:

Here is my take... I'll never go back to the battery. Noise is one reason, but not my main motivation. If you run 15 feet of ground wire, you are decreasing the efficiency of your your system. The long run of ground increases resistance which will rob your system of power and is one main cause of "dimming headlights". Also, I will never use a capacitor.

If you are running a multi-amp set up, you must be sure to use equal legth ground leads to the same location. Hook your higher power, larger gauge ground closest to the frame first, then the lower power, smaller gauge ground on top of it.


[Modified by leolufse, 6:00 PM 11/28/2003]

 

Hi Lars,
At least you didn't bust on me for "going both ways" :smash:

So what do you base your info on? Esp the capacitor part?

Maybe all my years of college studying electronics were a waste. Damn, I knew I should have not drank so much during the school week. I probably should have stayed awake during all those class too.

If at all possible I will use the car's frame as a ground. 0-guage wire does not come cheap and the convience of not having to run an additional wire to the battery are the major reasons why. The the only car I have run the ground to the battery is the vette and it works great, no light dimming, no noise.The vette still has the factory alt but a 15 farad CAP added.

"Scottie, we need more power"
:jester

 

Uh oh.........now this is going to tunr into a capacitor thing :hurray: Well I was having a decent debate on another forum about this a few weeks ago. Two guys there stated that caps do not work and gave their reasons which included claiming that some top car audio names...including Richard Clark backed this up. Now I have personally had a few conversations with Mr. Clark about caps many many moons ago and he was all for them. Ofcourse things change. So I asked these gentlemen to provide some literature to back up their claims and that is pretty much where the conversation ended. I looked several times but found nothing to support the idea that caps are "bad". Maybe you guys know something I do not and would like to know. I personally have used caps for as long as I can remeber and have never had one cause problems. I can not recal a situation where I went "HOLY SH&T THAT CAP IS BAD butt....MY CAR IS SOOO MUCH LOUDER!!!" either. So for me it is a thing that has just always been there.

Now if this is not turning into a cap discussion please disregard my above babbling and continue with the before mentioned topic.

I can not believe he goes both ways :lolg: :lolg: :lolg:

 

would it be this one ?
http://forums.corvetteforum.com/zerothread?id=667522

I don't know if I ever saw a vehicle competing in a sound off without a cap? I have seen them with a ground going to the rear though :)
I would take whatever Richard Clark has to say is right, he has more knowledge in audio than all of us put together.

Finally, the only thing I could possibly think of why a cap could be bad is the old wife's tale of them exploding. I have personally seen bigs caps get dischaged why the power was still applied. It will scare the crap out of you because it is like a shotgun going off. This would happen almost ever time one of my techs would take a top off a certain (Rockwell Collin) RF amplifier or worse yet when the top came up a little when the amp was in service. The amps had spring loaded clips on it with a metal tab that you were susposed to rock back and forth to discharge the caps with no problem. BUT, that tab could and would sometimes come loose from it's holder and BAM!!! You pooped your pants. :bb I'd say I'd seen this a dozen times or so and not once did the cap explode or shock anyone. The sound was from arching and yes it does leave a nasty burn mark on the tab, sometimes welding it to the cap. Now these cap were larger than any I've seen in car audio. Before you say "well, I could charge up a cap and toss it to you and if you touched the leads, you would get nailed". That is true. I can also shuffle my feet across the carpet and get you too
:eek: (I should have never taught my daughter that :banghead: )

I wish there was someway you could send that little shock through the computer cause I'd send on now to my vette friend EatRice :jester

PS make sure you ground the cap back to the battery :smash: :rofl: :lolg: :lolg: :rofl: :jester