Should I wire my amp ground to my battery?

[helotaxi 5,000+ posts]

Do you think that a 1/2" thick piece of copper has more potential to carry current then literally a ton of steel and/or other alloys.

In a lot of cases, yes. The "steel and/or other alloys" are not consistent in their conductive properties and in no way provide a direct path to ground. Lots of welds of unknown electrical quality in the way. A spot where the chassis flexes will change the conductive properties of the steel at that point. Glued lap joints are common in unibodies and don't conduct. Just because it's a massive hunk of metal (that's more than 10x the resistance for a given cross section than copper, BTW) doesn't mean that it's a better conductor than a large hunk of copper wire (20' of 1/0 has a resistance in the thousandths of an ohm.)

 

[DarkFox 10+ year member]

Agree with what your saying, were kinda talking about different things though. Your pointing out that the chassis is a shitty conductor in that there is resistance and noise. Which is what I was saying too

I was just pointing out that the car can handle more juice then the wire, and that the reason people are using wire isn't sheer current ability, its the better ground

I no where said the chassis was a better conductor:fyi:

 

[n2audio 5,000+ posts]

False. The battery's - terminal is THE ground for the cars electrical system. It is the only actual ground in the car. Grounding to the chassis is the electrical equivalent to splicing into something else's ground

,

True, and in some cases perfectly fine.

FALSE

Ground loop is a common problem. if it wern't, there wouldn't be a sticky about it

Also, the current from EVERY CIRCUIT IN YOUR CAR runs through it. Thats why you don't get ground loops. A ground loop is a separate loop considered ground feeding into a true ground.... not a direct path of its own (I.E. directly to the battery.)

FALSE. There is almost 0 resistance in 4 or 8ga wire. Guaranty if you ground a multimeter somwhere in the back of your car, and go to the neagative post of your battery there will be much more resistance then if you measure even a 20ft (long for car audio) peice of 4 or 8ga ground cable.

nty

FALSE

Do you think that a 1/2" thick piece of copper has more potential to carry current then literally a ton of steel and/or other alloys.

The chassis is a noisy place, probably the worst in the car. I think the reason you see people with these massive systems running there own grounds with 0ga or better, is cause if your putting that much into your system you are well informed and trying to set yourself up for success from the start.

In short, the battery is usualy the best spot to ground, though the addition of a long strand of high gauge wire is expensive for the ground, which offten can be taken from the chassis with no ill affects and save money. Though if you take this route, at the very least perform the big 3 so that the wire comming off the battery and going to the chassis isnt the choke point in your system.

you guys can both eat a d!ck

I'll stick with practices and theories that have been preached by industry professionals for yrs.

 

[n2audio 5,000+ posts]

FALSE. There is almost 0 resistance in 4 or 8ga wire. Guaranty if you ground a multimeter somwhere in the back of your car, and go to the neagative post of your battery there will be much more resistance then if you measure even a 20ft (long for car audio) peice of 4 or 8ga ground cable.

nty

That's wrong. Plain and simple. A car's chassis can carry a LOT more current than a 15' of 8 ga, or 4. One test by a person I consider HIGHLY competent in the field found an average car's chassis to be less resistive than 1/0.

 

[IgnoreMe 5,000+ posts]

you guys can both eat a d!ck
I'll stick with practices and theories that have been preached by industry professionals for yrs.

im not trying to be a dick, but how is grounding straight to the battery using 1/0 wire any different than grounding to the chassis, which in turn is grounded to the batt neg?

if you really think about it, when you ground to the frame all you are doing is splicing into another "wire"...except this wire is unrolled and shaped like a car chassis (if that helps bring a visual), is more resistive, and has "butt connectors" (welds, glued joints, etc like helotaxi said), connecting each piece of chassis shaped wire.

like i said not trying to be a dick, but if you really think about it, the chassis is nothing more than another "wire"

 

[n2audio 5,000+ posts]

FALSE. There is almost 0 resistance in 4 or 8ga wire. Guaranty if you ground a multimeter somwhere in the back of your car, and go to the neagative post of your battery there will be much more resistance then if you measure even a 20ft (long for car audio) peice of 4 or 8ga ground cable.

nty

FALSE

Do you think that a 1/2" thick piece of copper has more potential to carry current then literally a ton of steel and/or other alloys.

WTF? wire has "almost 0 resistance", but not more potential to carry current than the chassis? Which is it?

 

[n2audio 5,000+ posts]

im not trying to be a dick, but how is grounding straight to the battery using 1/0 wire any different than grounding to the chassis, which in turn is grounded to the batt neg?
if you really think about it, when you ground to the frame all you are doing is splicing into another "wire"...except this wire is unrolled and shaped like a car chassis (if that helps bring a visual), is more resistive, and has "butt connectors" (welds, glued joints, etc like helotaxi said), connecting each piece of chassis shaped wire.

like i said not trying to be a dick, but if you really think about it, the chassis is nothing more than another "wire"

but the electrical properties of a car's chassis are VERY different than copper, and presents a certain amount of resistance - exactly how much, who knows?

Even if the metal in a car WERE similar to copper (steel has about 9x the resistance of copper) there are welds, rivets, stamps, adhesives, sealers and I'm sure plenty of other stuff effecting the flow of current through the chassis.

But the one company test I know of set an average of 1/0 to be the point where a 15' piece of wire is less resistive than a car's chassis.

Another test done by an engineer in the field that I personally regard as an authority on the subject got results closer to 2/0.

These tests can't be done with a DMM and don't know why someone like dark fox who seems to know as much as he does would suggest doing such a test.

 

[IgnoreMe 5,000+ posts]

but the chassis is very different electrically than copper, and presents a certain amount of resistance - exactly how much, who knows?But the one company test I know of set an average of 1/0 to be the point where a 15' piece of wire is less resistive than a car's chassis.

Another test done by an engineer in the field that I personally regard as an authority on the subject got results closer to 2/0.

These tests can't be done with a DMM and don't know why someone like dark fox who seems to know as much as he does would suggest doing such a test.

i can understand that, i was moreso arguing the "noisy battery". you are grounded to the "noisy battery" with either the ground run, or the chassis "wire". you have to reach the same destination.

i just use 1/0 for ground runs because i dont trust my chassis. i mean a honda will probably have different chassis characteristics than a 88 f series truck. i know i dont trust my 98 explorer lol

 

[DarkFox 10+ year member]

WTF? wire has "almost 0 resistance", but not more potential to carry current than the chassis? Which is it?

apparently alot of people can not understand what I am saying so I will try to make it clearer.

1. RESISTANCE HAS ZERO IMPACT ON ABILITY TO CARRY CURRENT.

2. Resistance resists the flow of electrons, making a more resistant material a poor choice for ground

3. Most Cars are not made of a solid material. As other have said they have tack welded / glued spots, etc etc. Creating resistance in the circuit.

4. If you were to hook up 2 power supplies side-by-side, both capable of insane current supply, one to a piece of 0ga, and one to a car chassis and slowly turn them up till they fail, despite the chassis electrically being a worse conductor (I.E. more resistance per foot,) then the wire would catch on fire/melt before the chassis. Hence me saying, wire has "almost 0 resistance", but not more potential to carry current than the chassis" Which is a Completely true statement.

If someone tries to correct the inaccurate information you are trying to pass to other people and the best thing you can come up with is "Eat a dick" and respond with inaccurate assumptions of quotes from them, further illustrating your lack of education on the subject, maybe you should just give up.

 

[DarkFox 10+ year member]

i can understand that, i was moreso arguing the "noisy battery". you are grounded to the "noisy battery" with either the ground run, or the chassis "wire". you have to reach the same destination.
i just use 1/0 for ground runs because i dont trust my chassis. i mean a honda will probably have different chassis characteristics than a 88 f series truck. i know i dont trust my 98 explorer lol

This is a example of a informed person BTW. Using the 0 gauge cause he knows it is a BETTER ground then his chassis, not for current reasons. Chassis very greatly, 1/0 doesnt

 

[DarkFox 10+ year member]

FALSE. There is almost 0 resistance in 4 or 8ga wire. Guaranty if you ground a multimeter somwhere in the back of your car, and go to the neagative post of your battery there will be much more resistance then if you measure even a 20ft (long for car audio) peice of 4 or 8ga ground cable.

That's wrong. Plain and simple. A car's chassis can carry a LOT more current than a 15' of 8 ga, or 4. One test by a person I consider HIGHLY competent in the field found an average car's chassis to be less resistive than 1/0.

Again, illustrating you do not understand the difference between resistance, and ability to carry current. I did not say that the 4 or 8 can carry more current, I said it had less resistance.

 

[DarkFox 10+ year member]

One test by a person I consider HIGHLY competent in the field found an average car's chassis to be less resistive than 1/0.

This is a useless fact without knowing the constuction of the vehicle (unibody or something with a solid frame) and the material or alloy that that specific vehicle was. A better statement of it would be,

ONE (one in caps as onces is not enough for scientific experiment. Must be able to repeat under any condition) test by a person I consider HIGHLY competent in the field found (average car's **WRONG - How do you avereage ONE CAR**) (replace with - on a model year XX, Make , model, I found the) chassis to be less resistive than 1/0

 

[DarkFox 10+ year member]

sorry to anyone not involved in this, I was stating facts before, not being a jerk, that is until I was told to "eat a dick"

 

[n2audio 5,000+ posts]

If you were to hook up 2 power supplies side-by-side, both capable of insane current supply, one to a piece of 0ga, and one to a car chassis and slowly turn them up till they fail, despite the chassis electrically being a worse conductor (I.E. more resistance per foot,) then the wire would catch on fire/melt before the chassis. Hence me saying, wire has "almost 0 resistance", but not more potential to carry current than the chassis" Which is a Completely true statement.

As it applies to the situation at hand - I disagree.

we're not talking about ultimate conductor failure - we're talking about voltage drop which you can surely agree goes to resistance.

I've seen 2 test conducted by completely unrelated sources both of which arrived at around 1/0 as the point where copper is more conductive than the "typical" car's (unibody) construction.

One other thing I was hoping you could clarify ---

False. The battery's - terminal is THE ground for the cars electrical system. It is the only actual ground in the car. Grounding to the chassis is the electrical equivalent to splicing into something else's ground

Is the alternator NOT the only "actual" ground when the car is running?

 

[DarkFox 10+ year member]

no, the battery is still what evething in the car grounds to, including the alternator, which is why you can put a noise filter on that as well, to further isolate it from the rest of the cars electrical system. Unless you disconnect your battery while the car is running.... but you wouldnt run it like that.

Also, with what what you said about the 1/0 being more conductive in the seance that you are talking about (less resistance per foot) The thickness from a 4ga to a 1/0 should not be a factor in car audio. Unless you are getting so thin that the cable is unable to handle the test signal, resistance is a property of the material used, and when hooked up to a multimeter, a 20ft strand of 1/0 copper should have almost identical resistance to a 20ft strand of 4ga copper. The actual answer as I looked up this morning to re-verify is that the resistance is directly proportional to the length and inversly proportional to the cross sectional area. So there is a resistance difference from 4 to 1/0 but hardly noticeable @ a 20ft length. Something in the m Ohm range.

Sorry about the way I was talking earlier also, I dont mind disagreements or different points of view, but I think name calling, threats, or whatever else commonly takes place on forums is silly, and takes away from the actual thread.

No hard feeling.

DAMIT, I have a piece of 20ft 4ga and a unibody car, but my multimeter is dead >.