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Ground to battery. Right or wrong?


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dblboinger 
Member - Posts: 8
Member spacespace
Joined: December 05, 2006
Location: United States
Posted: December 05, 2006 at 1:38 AM / IP Logged  

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?

,

Fastlearner 
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Joined: March 23, 2005
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Posted: December 05, 2006 at 3:44 AM / IP Logged  
Don't run the ground all the way up front. Just screw it to metal in the trunk. Also I think that running the wires under the car are probably best(protect the wire).
cmrs2k 
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Posted: December 05, 2006 at 8:16 AM / IP Logged  
Greetings.  If you do run under the vehicle, some type of conduit would probably be wise.  Also, not to cause an arguement, but I had my system setup with a 1/0 shot from the battery for power and then my ground went to the frame.  My bass amp kept giving up.  It kept reading the low voltage warning when it did.  I tried the ground at several different bolts, installed my own ground lugs, etc.  It still failed rather often.  I then ran a 1/0 ground shot from the battery.  No failures yet.  Now, I will say that this is probably more vehicle specific in this case, and that ground to battery or to frame is not the only variable. 
Chris R.
prosound 
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Posted: December 05, 2006 at 10:56 AM / IP Logged  
I've always been tought you want your ground as short as possible, running it to the battery would be pointless...
Stephen Theno
Pro Sound
Lawrence,KS
DYohn 
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Posted: December 05, 2006 at 11:24 AM / IP Logged  
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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sin0cide 
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Joined: August 03, 2006
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Posted: December 05, 2006 at 11:34 AM / IP Logged  

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)

geepherder 
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Posted: December 05, 2006 at 7:41 PM / IP Logged  
Just to add to what others have posted, you're factory wiring (battery/alternator/grounds) should be upgraded to at least the size wire you're using for your system. That way, when you ground to the frame, there's no "bottle necking" so to speak. Read the "big 3" sticky. Also keep in mind if you're exceeding the current output of your alternator, that'll need to be upgraded as well.
My ex once told me I have a perfect face for radio.
dblboinger 
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Posted: December 05, 2006 at 10:36 PM / IP Logged  

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.

aznboi3644 
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Posted: December 05, 2006 at 11:53 PM / IP Logged  
DYohn wrote:
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.
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
memphis9 
Copper - Posts: 53
Copper spacespace
Joined: November 12, 2005
Location: United States
Posted: December 06, 2006 at 9:53 AM / IP Logged  

aznboi3644 wrote:
DYohn wrote:
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.
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

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.

G-Boys Customz
Northville, MI
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