Ground Chassis v. Ground Neg Bat Terminal
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=49746
Printed Date: May 12, 2025 at 11:07 AM
Topic: Ground Chassis v. Ground Neg Bat Terminal
Posted By: brianrwebb
Subject: Ground Chassis v. Ground Neg Bat Terminal
Date Posted: February 09, 2005 at 8:01 PM
what are the cons to supplying a ground for your eqiupment directly from the negative terminal of the battery? is the potential for inducing more noise into the system greater? versus a clean ground to the chassis? i know the length of cable will always be less for grounds to the chassis, as runs to the negative battery terminal would be lengthy from anywhere within the car, especially for those items mounted in the trunk, however, i think of the car chassis as one large negative battery terminal. should i not think of it as this, and remember that a shorter ground length is of the utmost importance as long as termination of the ground point is secure and solid to chassis metal? for the first time in an install of my own, i have developed alternator whine, and it is extremely discouraging -system sounds great when car isn't running, but as soon as ignition is turned on, horrible whine with variation in engine speed is present, and unbearable. to amp- fused 8 gauge to positive terminal, 8 gauge to negative terminal, rca's from hu to amp, remote lead fead from acc+ in wiring harness. i have read countless past posts here through search and most will find this post redundant, but it seems alternator whine is luck of the draw. any opinions? thanks, Brian
Replies:
Posted By: Alpine Guy
Date Posted: February 09, 2005 at 8:33 PM
Are your amps mounted directly to body metal? if so try mounting them on wood so the chassis dosn't touch any metal.
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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.
Posted By: Poormanq45
Date Posted: February 09, 2005 at 8:39 PM
Ground directly to the negative terminal is ALWAYS the best. This will give you an almost nill resistance path for the ground. Whereas grounding to the chassis will give a much higher relative Ohm level. The thing is, the chassis is not a really good conductor of electricity, whereas a copper wire connected to the battery terminal is an excellant conductor
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Posted By: School_Zone
Date Posted: February 09, 2005 at 8:44 PM
Run your RCA signal wires along the opposite side of the car as the amplifire power wire.
Posted By: Poormanq45
Date Posted: February 09, 2005 at 8:49 PM
Yep.. The power wires generate electromagnetic interference, which will cause a "hissing" noise in the audio if the RCA cables are run along power cables
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Posted By: brianrwebb
Date Posted: February 09, 2005 at 8:59 PM
yes, rca's are on opposite sides and, no, the amp, is on the vinyl material underneath the seat, not metal. hey, as long as i don't 'drive' the car, everything sounds beautiful!
Posted By: stevdart
Date Posted: February 09, 2005 at 9:44 PM
If your amp is screwed down into the sheet metal you could remove the screws to test. If the screws grounded the amp then screw the amp to a piece of plywood, then screw the wood to the floor.
Posted By: brianrwebb
Date Posted: February 09, 2005 at 10:04 PM
unfortunately, i have done as you suggested, to floor, to wood, to wood then floor, grounding of the amp is not the problem, guess i'll just get a 12V in-line choke or capacitor and pray for the best.
Posted By: School_Zone
Date Posted: February 09, 2005 at 10:44 PM
Ground directly to the negative terminal is ALWAYS the best. This will give you an almost nill resistance path for the ground. Whereas grounding to the chassis will give a much higher relative Ohm level. The thing is, the chassis is not a really good conductor of electricity, whereas a copper wire connected to the battery terminal is an excellant conductor
This isn't always so. The floorpan of the car will act as a much heavier gauge conductor (thus less resistance) than a wire running from the trunk all the way back to the hood. This is especially so if you've upgraded the battery-to-chassis and engine block-to-chassis cables.
Posted By: ilvwhtgrls
Date Posted: February 10, 2005 at 12:32 PM
Your battery is grounded to your chasis so I do not see the benefits of running a ground directly to your battery. If anything, there is much more resistance in running another strand. If you properly ground something to the chasis of your car, use a wire brush it will yield the same results if not better then going directly to your battery.
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Eye am so re todd did.
Posted By: jstruckman
Date Posted: February 10, 2005 at 12:55 PM
Use a meter to check the resistance of the ground point for the amp to see if the ground is good or not, there is a sticky on this forum showing you exactly how do it. Testing is always faster and easier than trial and error situations such as this. As long as there is no resistance on the ground point then it wont matter if the ground is coming directly from the battery or to the chassis.
Jazzy
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Posted By: forbidden
Date Posted: February 10, 2005 at 4:15 PM
Wahoo, someone actually reads the things I write, imagine that. The last two posts I read before yours, by the sounds of it, these people have not read the thread yet. To the original poster, please read both of the sticked topics on grounding at the top of the forum. What is the chance that you have a Pioneer cd player? Haha, "friends don't let friends buy Sony", I've been saying that for over 10 years. ------------- Top Secret, I can tell you but then my wife will kill me.
Posted By: Drewt
Date Posted: February 10, 2005 at 10:40 PM
try grounding your amp and HU to the same point.....may not help, but should.... -Drew
Posted By: brianrwebb
Date Posted: February 10, 2005 at 10:58 PM
thank you guys, will be trying anything and everything this week, starting with the meter, but it's trial and error after that.
Posted By: Poormanq45
Date Posted: February 10, 2005 at 11:59 PM
Forbidden: I read the sticy  .
I understand where that person is coming from about the chassis causing the conductor to be of a heavier grade. You must understand though, the chassis is usually made of aluminum or steel, both of which are extremely poor conductors relative to copper. For my car, I ran three 2 guage wires from the battery all the way to the trunk. One on each side, and one down the middle. This gives me a nill resistance ground.
IIRC, resistance = Cross sectional area x length x Ohms per unit of length. -------------
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