indosia
10+ year member
CarAudio.com Elite
Makes scense, better to ground to the rear deck then running a wire all the way back to your batt. And its a good idea to sodier your ground.
indosia
helotaxi
5,000+ posts
Kilroy was Here
There's a big difference between worrying about structural integrity and electrical conductivity. If it was as simple as all you guys seem to think that it is then there would be no such thing as ground loops. Ponder that one for a second.
I was referring to the FACT that a car's chassis has a lower resistance to power than any type of electrical wire that you would be able to run directly. Resitance is not the issue when it comes to grounding to the chassis it will always be less.
Unless you are running your seprate wire to a SEPRATE battary completely isolated charged by a SEPRATE alternator and run your system off of that you will still get ground loops.
Ground loops occour when there are grounding diffrentials between one peice of equipment and another that are connected.
This potential diffrence causes a ground loop. It can just as easily occur in a system that is grounded directly as one that is grounded to the chassis. Why? Cause you are still connecting the ground to the SAME ELECTRICAL CIRCUT!!
Electricity flows wherever it wants whats to prevent your radiator fan from:
- grounding to your chasis
- THEN going through the wire that you connected to the SAME ELECTICAL system at the battary instead of the chasis and causing a loop at your amp?
Dont beleive me? Take an OHM meter attach one end to your "special ground wire" that is attached to the negative pole of the battery and take the other one and touch any bare spot on the chassis...
You will get a reading... they are connected...
Think about it the negative pole of your batt is still connected to a million and a half other things.
Adding a copper wire is about as useless as tacking on another peice of sheet metal to your car....
If you want to do somthing useful take a distributon block and run ground wires to sevral points in your chassis so that the negative pole of your battary can take the most advanage of the immense conductive cabability of your chassis.
See pics below...
helotaxi
5,000+ posts
Kilroy was Here
Um, duh. Ground? Measure the resistance of that wire. Measure the resistance of the typical ground point in the back of the car back to the battery negative. There is a reason that so many people have trouble finding a good ground. The sheetmetal of the car is not as good a conductor as you seem to think.
So? So is your TV, computer, toaster, the whole city power grid is one big parallel circuit, just like a car. In a parallel circuit, where does the current flow? Through all loads on the circuit with the most current taking the path of least resistance.
This is totally counter to your whole argument and since this does work (well known in performance circle to increase spark power) then your argument is flawed. If the chassis is such a great conductor, one ground wire of 1/0 should be enough. If the chassis is such a great conductor, then that 3 foot run of copper wire to that point on the other side of the engine bay would be useless, as would all the other wire you added. Since they are not useless, then the chassis must not be the god-like conductor you claim it to be.
I'm obviously not going to convince you. I know I'm right so you are at an impasse with me. Let's agree to disagree.
Good enough...
Actually it is known in the automotive perf. world to be complete hype... Dyno tests show zero increase in HP in most cases.
The reason I posted that is because the higest point of resistance on your chassis is the 1 or 2 gauge copper wire running from the ground pole to the body of the car that creates the ground in the first place. Not the chassis itself.
If the chassis is well grounded you take the most advantage of the cars unibody which cross sectional area is phenomenal.
The reason that I see most people have trouble finding grounds is because areas arent stripped of paint and cleaned before attaching the ground lead... That means everything the bolt, the threads and anything underlying that bolt.
Also a suprising number of people are stupid and find grounds that are really only attached at a few places... I swear I saw this one guy in his saturn with his ground connected to his trunk lid and was asking me why the stereo kept cutting out... well DUH its only attached at 2 places with HINGES. On top of that the body is mostly PLASTIC! In this case I would probably use your method of grounding for higher power applications.
To keep it simple I only ground to the chassis in places I know are solid... Usually its the seat bolts or the rear shock tower.
About housing... AC ground loops are a bit more complex because current flows in both directions... so its not really a good thing to compare it to. Current reverses direction 60 times per second.
I know where you are going with this... you think that a single straight shot of copper wire provides the best solution... I don't disagree it does no harm but I do think it is unneeded...
Given that you do approprately ground the chassis and do attach it to a good ground point Its just a waste of copper IMHO...
Thats my take...
helotaxi
5,000+ posts
Kilroy was Here
For this to make sense you would have to do the same with your amp grounds as well. And then assuming you were right about the chassis (which I will not concede) being a better conductor you have just introduced a ton more copper into the circuit. Current does not flow uniformly through a conductive material and that is the major flaw in your assumptions on which you base your whole argument. If the whole of the chassis was usuable then it might be the best solution but that isn't the case.
We do agree then on the fundamental point of the whole dispute that arose the first place.
I have never said that running just a chassis ground wasn't almost always adequate. That isn't the way my syatem is wired but that is my anal retentive side coming through. 1/0 wire to the rear (power and ground) and 4 ga to each amp even though they are only pushing total about 500 watts. I would completely isolate the system from the car electrics but I don't have the room in the car to run another alt that I could electrically isolate.
indosia
10+ year member
CarAudio.com Elite
Single point grounding is the best way to eliminate ground loops. Another way is to take a wrench and bridge the + aND - posts on the top of your battery :blow_up: :hilarious just kidding
helotaxi
5,000+ posts
Kilroy was Here
Have you ever seen the results of that happening?! Chrome-Vanadium steel is some tough stuff but that will mess it up. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif
Sadly yes, i have. I was tightening a side mount bolt on the postive side of my battery without taking off the - (i thought i'm only tightening a bolt, nothing could happen) Dang one turn and i slipped and hit the frame...fourth of july in my engine bay for a split second....luckily no harm to me or my car ( i don't think so yet)
fast4door
10+ year member
Team Loud Concepts
Ok, since evrybody is in disagreement lets throw this one out there!! Why connect 2 wires from your head unit to each speaker and not just the positive then wire all the grounds to the chassis?
Also think about this, your amp is grounded threw the chassis which is grounded to the motor then to the battery, everything else is connected to the chassis, this means they all have to fight to find their ground, this causes resistance, not to mension if your Sparkplug wells fill oil or water you will be sending unwanted positive current threw your chassis into your amp, alt, cap, PCM etc.... This could = big problems!!! expecially if it get all the way to the cap that s h i t will act like a bomb!!!
helotaxi
5,000+ posts
Kilroy was Here
Common ground? This is way it used to be done in older cars. Modern car audio components do not work this way. The signal path is shielded from ground to prvent noise.
Actually, your battery is grounded to the chassis usually. Your alternator is grounded to the engine block which is grounded to the chassis to complete the circuit.
Doesn't work that way. Your plugs are grounded to the block anyway so the water thing is moot (not to mention that pure water is not a conductor). High power spark coils have been known to induce noise anyway (a popping sound heard through the speakers) but this is radiated noise not electrical interference and poorly shielded plug wires are generally the culprit. There is no "fighting for ground," it's all one big parallel circuit powered by the battery/alternator (depending on whether the car is running or not) with the battery - terminal or the alternator case as the reference ground. Current takes the path of least resistance (most of it anyway) back to the reference ground. Noise can be caused by multiple loads (especially "noisy" components such as blower motors and ECUs and fuel pumps) sharing the same "path of least resistance" back to the reference, though. The aircraft I fly is a perfect example. You can hear a whine in the intercom when you turn on the blower fan. You can hear a whine from the inverters. You can hear the ignitor plugs firing during the ignition sequence. All of this is from the pulsed DC created by the DC motors and spark exciter box and the switching power supply of the invertors (solid state type) sharing ground paths with the various components of the intercom system. That chassis has twice as much metal in it as your car and is a ground loop nightmare.
fast4door
10+ year member
Team Loud Concepts
Not to start bashing but Go get a chiltons manual and take a look then you might want to rethink your answer!! Most cars do share a common ground newer or not, this means there will be some more resistance than taking a wire directly from your battery!! Like everyone else has said IMO!!! If you want the best do it the best way, no resistance is better than some, even if it's just .00001 ohm!!
Some one please tell me where I can get pure water!! I am a aquarium hobbyest and I have yet to find some one who can get me pure water!!
helotaxi
5,000+ posts
Kilroy was Here
Go look at every car I have ever owned. The battery IS grounded to the chassis. The block IS grounded to the chassis as well usually in more than one place. Some cars probably do ground the battery directly to the block, but not one I have ever owned or worked on.
When talking about common ground I am refering to speaker grounds, not component grounds. Check behind your dash or look at the wiring diagram for you head unit in your Chilton's. If it is a newer car then it has two wires for each speaker.
DI water. Try a chemical or medical supply place. Pure enough for all practical purposes and it does not conduct until some type of electrolyte is introduced.
Car Trekker
10+ year member
Member
Simple test for you....
Go ahead and run a ground wire to your battery.
Get your amps running wth a test tone so they're drawing maximum current. 80 to 100 amps should do it.
Connect a DMM between your amp ground terminal and the battery post, set the meter to microvolts, and measure the voltage.
Now try it again with your car as the ground path and measure again.
The lowest number wins.... Period.
Any betting men in here?
Go ahead and run a ground wire to your battery.
Get your amps running wth a test tone so they're drawing maximum current. 80 to 100 amps should do it.
Connect a DMM between your amp ground terminal and the battery post, set the meter to microvolts, and measure the voltage.
Now try it again with your car as the ground path and measure again.
The lowest number wins.... Period.
Any betting men in here?
fast4door
10+ year member
Team Loud Concepts
DI water: De-ionized water, still full of heavy and light metals, also full of all sorts of contaminents. Water is one of the best conducters of electricty there is!!
RODI Water: Reverse Osmosis De-ionized water, the cleanest pure water availible, yet still very conductive of electricity. Ive had the piss shocked out of me after just filling a bucket in the warehouse, set the bucket down when to put the top on and BAM!! So there is where and how I get my reasoning for calling your bluff!!
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