Ground to battery. Right or wrong?

Brand new member. Wish I had known about this forum sooner.

I'm installing a 5.1 system in my RX7. Total power will be about 1500 watts. I bought enough 1/0 gauge cable, both power and ground, to run all the way to the battery. When I mentioned to the guys at CarToys that I was planning to run the ground all the way to the battery they said not to because it will add noise. Seems to me this would be the best way to go and if anything should prevent noise.  Any comments on this?

Any recommendations on how to get 1/0 gauge cable through the firewall? Can I run through the floor back near my amps and run the cable underneath the body? Should I use conduit if I do?

Finally, I'd like to ask for some recommendations on my center channel. My car, a '93 RX7, has a center channel speaker. It appears to be maybe a 1" speaker. Not sure if the mount can be enlarged. Anybody ever dealt with this? What would you recommend?

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it could have something to do with the size of wire that a stock battery is hooked up with which is more like 4 gauge. I would rerun the ground wire with a thicker guage and run one to the actual frame aswel. (upgrade your big 3)

No dis to anyone who has replied, but what are your responses based on? Experience or just an opinion? The following is an excerpt from another thread posted by Rob @ Forbidden Audio. He appears to be present throughout this forum on a wide variety of subjects and he states:

"To add to this, a good ground for car audio applications will have a return resistance reading of 1/2 ohm or less. I have yet to have a return reading of 0 ohms. If a ground return reading cannot be made to get below 1/2 ohm by means of the "BIG 3", then it is adviseable to ground direct to the battery."

If grounding to the battery is recommended when the "BIG 3" fails, then why would it not be recommended any other time? Maybe I won't gain anything, but I shouldn't lose anything either, except the cost of the cable and the time to do it.

BTW, I'm in the process of upgrading all power ground cables to 2 gauge. If I direct ground my amps I'll use 1/0, just like I'm using for the +12. This RX7 is a bitch to work with in some ways. And some of the things they did don't make any sense. For instance, they came off the battery + to a fuse box using 4 gauge. At the fuse box, paralleled on the input side is a 1 or 2 gauge cable going directly to the starter. After passing through the "MAIN" fuse there are 2 - 4 gauge cables running to each of 2 more fuse boxes. Talk about a "bottle neck".  I also don't understand why they ran through the "MAIN" fuse to go to the other 2 fuse boxes. What's the point? If anything on either of the "SUB" fuse boxes has a problem it's going to open a fuse in it's respective fuse box well before it opens the 120A MAIN. I'm seriously considering running the starter direct to the battery as well using 2 gauge and running new to the "MAIN" fuse box and new 4 gauge from the "MAIN" fuse to the 2 "SUB" fuse boxes. According to my calculations of current draw this should be more than adequate.  All my lugs will be soldered and I'm using Tsunami battery terminals.

Regardless, I appreciate all the input. Wish people on my other forums were this willing to help out. You guys/gals are great.

DYohn] wrote:

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Keeping ground as short as possible is always the best bet, however some vehicles (especially uni-body Fords) have very poor ground return resistance to the alternator (it's actually the case of the alternator that is the true ground in a car, not the battery negative terminal.) So, if your ground return resistance is high, running a proper cable back to the battery or to the alternator case is sometimes the only way to eliminate ground loop hum. Measure the return resistance, if it's less than 1 ohm you are not likely to gain anything by running a cable to the battery.

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aznboi3644 wrote:

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DYohn] wrote:

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Keeping ground as short as possible is always the best bet, however some vehicles (especially uni-body Fords) have very poor ground return resistance to the alternator (it's actually the case of the alternator that is the true ground in a car, not the battery negative terminal.) So, if your ground return resistance is high, running a proper cable back to the battery or to the alternator case is sometimes the only way to eliminate ground loop hum. Measure the return resistance, if it's less than 1 ohm you are not likely to gain anything by running a cable to the battery.

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Question about this ford thing because I have a ford.

Are the 98 explorers unibody??

So the ford unibodys have bad grounding to the body and need a ground to the battery??

Sorry if this is kinda like thread jacking

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Explorers are not unibody. They have a full frame. I have done a few installs on explorers. I have never had  the problem of ground loop hum from grounding to the frame of a explorer.  I did have a problem of ground loop noise in my Mustang when I did ground to the body. But the problem was fixed when I grounded directly to the battery.

dblboinger wrote:

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If grounding to the battery is recommended when the "BIG 3" fails, then why would it not be recommended any other time? Maybe I won't gain anything, but I shouldn't lose anything either, except the cost of the cable and the time to do it.

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[QUOTE=stevdart]

The ground wire must be constantly connected to chassis while power is supplied to the appliance (thus no fuse allowed).
Damage to the appliance will occur if the ground is disconnected while hot is still connected. 

Say what? Removing the ground is the preferred method of removing power from any electronic component, especially if microprocessors are involved (i.e. car stereo's, engine ecu's, etc.) Having worked in electronics for nearly 30 years I can tell you, I've NEVER seen a circuit damaged from removing/connecting the ground/common. The same can not be said about the supply. And can you imagine a car stereo where the wires are not hidden?

j_darling2007, don't get confused about the answer.  The topic is about the amplifier's ground connection, not the circuit ground.  Of course it is correct to remove the negative battery cable  (see link below) to open the circuit and shut off power.  Once there is no circuit, there is no power to any appliance (including amplifiers) that are connected to that circuit.  With a dead circuit it doesn't matter if the power and ground cables are disconnected from the amplifier, or in what order.  But even so, even with the circuit open and no available power, the ground is always connected first to the amplifier and disconected last.  That is to say, you always ensure that the ground connection is made before the power is connected.

To the OP, you asked about the reason to ground the amplifier to chassis and I tried to give you a valid reason.   Here's another: 

Perry Babin said HERE in "Amplifier Installation Notes":

"If the amplifier's ground is properly connected to the body of the vehicle, it will provide a better return path to the charging system's ground than will a ground wire run back to the battery. This is especially true if the ground strap from the engine block to the chassis is upgraded."

Proper grounding of an amplifier can almost always be achieved through the floor pan, and with best possible results.  IF chassis grounding repeatedly fails after trying other nearby locations, you can run the ground wire directly through the car and engine compartment to a suitable grounding location.  By that time you will have tried and failed to get adequate ground return using the chassis, and so the next best hope for success is a wire directly to the source.

j_darling2007 mentioned the circuit ground, which the question doesn't pertain to.  But speaking of the circuit, if the circuit is live,  the amplifier is supplied power via two wires: positive and ground.  If the ground wire is long and snakes throughout the vehicle rather than being short at the amplifier's mounting location, there is a much greater chance of unseen damage that can occur to the wire.  Wouldn't anyone agree that a 15' wire has, at the very least, the potential of fifteen times greater risk of damage than a 1' wire?  And if this wire is severed or otherwise badly damaged while the amplifier is connected to a live circuit, what can likely happen?  

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

stevdart wrote:

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j_darling2007, don't get confused about the answer.  The topic is about the amplifier's ground connection, not the circuit ground.  Of course it is correct to remove the negative battery cable  (see link below) to open the circuit and shut off power.  Once there is no circuit, there is no power to any appliance (including amplifiers) that are connected to that circuit.  With a dead circuit it doesn't matter if the power and ground cables are disconnected from the amplifier, or in what order.  But even so, even with the circuit open and no available power, the ground is always connected first to the amplifier and disconected last.  That is to say, you always ensure that the ground connection is made before the power is connected.

Response: This has absolutely nothing to do with my original question. But to clarify the point of your statement, the damage caused by removing the amplifier ground is due to the fact that removing the amplifier's power ground does not completely remove what you refer to as the circuit ground. If you remove the power ground only, the amplifier will attempt to complete it's circuit through the RCA cables and will most likely blow out the front end of your amplifier because the input circuitry is not desinged to handle the amount of current common in the power ground. This is the reason there is a power ground to begin with.

 To the OP, you asked about the reason to ground the amplifier to chassis and I tried to give you a valid reason.   Here's another: 

Perry Babin said HERE in "Amplifier Installation Notes":

"If the amplifier's ground is properly connected to the body of the vehicle, it will provide a better return path to the charging system's ground than will a ground wire run back to the battery. This is especially true if the ground strap from the engine block to the chassis is upgraded."

Proper grounding of an amplifier can almost always be achieved through the floor pan, and with best possible results.  IF chassis grounding repeatedly fails after trying other nearby locations, you can run the ground wire directly through the car and engine compartment to a suitable grounding location.  By that time you will have tried and failed to get adequate ground return using the chassis, and so the next best hope for success is a wire directly to the source.

 

Response: If this is true there is absolutely no reason to ground directly to source, EVER. This also means there should be no such thing as a ground loop because all chassis parts are always at the exact same potential.

How anyone can say chassis sections that could be bolted together, loose, corroded or anything else short of being  welded, can possibly provide better continuity than a heavy gauge, multi-strand copper cable is beyond me.

 

j_darling2007 mentioned the circuit ground, which the question doesn't pertain to.  But speaking of the circuit, if the circuit is live,  the amplifier is supplied power via two wires: positive and ground.  If the ground wire is long and snakes throughout the vehicle rather than being short at the amplifier's mounting location, there is a much greater chance of unseen damage that can occur to the wire.  Wouldn't anyone agree that a 15' wire has, at the very least, the potential of fifteen times greater risk of damage than a 1' wire?  And if this wire is severed or otherwise badly damaged while the amplifier is connected to a live circuit, what can likely happen?  

Response: If, as you suggest above, all points on the chassis are at the same potential then it is irrelevant how long or short the cable is, or if it gets damaged. That is unless the cable is completely severed. If something significant  enough to completely severe a 1/0 gauge cable happens to my car, I doubt that an amplifier or two will be at the top of my list of concerns.

 

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I got what you are saying.  I thought you meant the entire electrical system, not just the amplifier.  Thanks for the response.

Jacob