Should I wire my amp ground to my battery?

[DarkFox 10+ year member]

This is gonna be my last post in this thread unless I see something completely wrong posted.

Were splitting hairs here.

To the OP, The IDEAL ground is to your batter, electrically speaking, it is the most direct path to ground you can get. In most cases, you can grab a ground from somewhere in your vehicle and get away with it, as it is all metal and has a wire running to your battery anyway, but you have a higher chance of getting a ground loop and hum, then you do if you select the proper gauge wire and run your own ground to your battery.

 

[helotaxi 5,000+ posts]

Resistance has EVERYTHING to do with the ability to conduct since there is a mathematical relationship between the two, as in one is the inverse of the other. Sure the body of the car can carry more current before it melts, it has more mass and more surface area and can dissipate more heat as a result. That's good, because with a higher resistance, it will have to.

The goal of using large gauge wire for amp power is to deliver the current to the amp with the smallest amount of voltage drop possible, right? 8 ga can actually carry a lot of current. The problem is that when you run a lot of current through it, the resistance of the wire causes a voltage drop proportional to the amount of current, you know V=IR? The chassis is no different. Resistance * current = voltage drop. If the goal is to minimize voltage drop we can either minimize current, which isn't exactly practical if we're trying to make power, or we can minimize resistance. You both admit that the chassis of the car by its design and construction has a fairly high resistance so why would you use it for a ground?

n2audio- You and I both know that a lot of the "industry practices" are dumb and don't stand up to solid science. And if you need the approval of an industry person to believe something, Manville Smith equates the typical unibody car to roughly 4ga.

Dark Fox- unless you have one hell of a multimeter, you can't measure the resistance of a 15' section of 4ga or the resistance of the ground path in the car. We're talking 36 ten-thousandths of an ohm. That's 0.0036 ohms. 1/0 is roughly a third of that.

 

[DarkFox 10+ year member]

Sure the body of the car can carry more current before it melts, it has more mass and more surface area and can dissipate more heat as a result. That's good, because with a higher resistance, it will have to.

If you read my whole first post that is the gist of what I said.

thats why I say wire > chassis

 

[n2audio 5,000+ posts]

n2audio- You and I both know that a lot of the "industry practices" are dumb and don't stand up to solid science. And if you need the approval of an industry person to believe something, Manville Smith equates the typical unibody car to roughly 4ga.

I'm not an electrical engineer, but I'm a scientist at heart, my career is in the civil field. I try to be sure anything I claim has a solid foundation in verifyable scientific fact. My statements regarding chassis vs battery are in reference to a thread a few years ago on carsound. Manville was involved and wasn't exactly positive on his 4 ga claim. He posted the cars, test methods and vdrop measurements.

Rob M had run similar tests on a couple personal vehicles and gotten smaller numbers, and RC recalled similar results in the past.

They all agreed simple differences in quality/location of the terminations could have made the difference.

The post involving manville and others...

http://www.audiogroupforum.com/csforum/showthread.php?t=37&highlight=esoteric&page=7

Esoteric Audio's tests:

Last post, made by...ME //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif a couple years ago.

http://www.sounddomain.com/ubbthreads.php/ubb/showflat/Number/193001/page/139

The car may not be that relevant ('85 camaro) but I believe it IS a unibody car - and even with a POORLY placed ground the chassis didn't drop more than 1/4v at 300A. If my calculations are correct that would indicate something around 3/0 copper equivalent.

And when you consider Esoteric would benefit financially by convincing everyone a battery ground is the best option - that test is saying something.

 

[n2audio 5,000+ posts]

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.

When someone tries to slice and dice my posts like I'm a babbling idiot making things up as I go I take offense to it, and I responded exactly as I would have if you were standing right in front of me.

but I'm over it //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[DarkFox 10+ year member]

//content.invisioncic.com/y282845/emoticons/respekt.gif.b162d148236010609fe523122efe3729.gif

 

[helotaxi 5,000+ posts]

Fair enough. You have to look at the cars in question and the ground location though. How old were the cars relative to the testing period and relative to now. A lot of material has been pared away from the structure of the modern unibody in the interest of meeting federal emmisions standards. Glue joints are becoming more prevalent in the interest of cutting costs. You might be able to find a 4ga or even 1/0 equivalent on every car tou there, I honestly don't know these days. What I do know is that if I run a 1/0 straight to the battery and another 1/0 from the battery to the engine block (which in effect takes it to the alt case through a VERY solid hunk of metal) I have a 1/0 ground with no guess work or time wasted trying to find an equivalent that may or may not exist. Now once you start talking trucks and SUVs with a body on frame construction, a frame ground is awesome.