why such a short ground wire?

I was reading an noise article on caraudiomag in particular this quote
"
Most car chassis are made of steel, which is not the best conductor of electricity, so you must add as much ground return current-carrying ability as possible by upgrading to larger wiring to the chassis."

So your battery is producing the ground since the car isnt really grounded due to being on tires, since the frame is a poor conductor....then how come its never advised to just run a large guage ground wire directly to your battery and off that to the frame?

I mean the juice has to travel from amps ground, to the frame then to the battery with the frame being a poor conductor, so a large wire directly to battery then from Neg post to frame would be a better conductor?....I know ground needs a short distance but if the frame is a bad conductor then i don't get it, i assume my idea doesnt work but can anyone enlighten me?

The actual ground in your car is not the battery, it's the case of the alternator.  The vehicle's "frame" is used as the ground plane for many reasons, not least of which is that even though steel is a worse conductor than is copper, the large mass of steel in a vehicle creates a much higher current capacity and much lower total resistance path to the alternator case than would all but the largest cables.  Plus it is MUCH cheaper to use the vehicle than it is to run long large gauge cables.  That being said, there are some cases when running a ground cable to the battery (or better yet, to the engine block) is necessary or advisable.  Some vehicles do not have a steel frame or use glued together bodies instead of welded which makes it difficult to achieve a ground return of less than one ohm.  Some vehicles are very noisy electronically and the only way to eliminate ground noise is by using a ground return cable.

I suggest you should read the "What is a good ground" post in the Hot Topics forum for more guidance.

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x2.
I know many that reckon chassis/bodies (steel) are "bad" and separate cables are required, BUT they never seem to substantiate their claims. (Nor state if ground loops then become a problem.)   

Granted, steel may be as bad as 3% of copper conduction (& up to 30% I think), but consider the cross-sectional area it goes through....

The only problems I am aware of are - as DYohn stated - insufficient coupling between panels etc.


It's simple to test though - a voltmeter between the alternator chassis (or engine, though strictly is should be where it bolts to the body/chassis) and the equipment chassis/ground.


As to jargon - I traditionally use chassis rather than earth or ground. But I deal a lot with inverters and mains equipment where "earth" and chassis can be very different.
But don't confuse a vehicle's ground with planet Earth ground/earth - as you said - there is rubber in between. Static shock anyone?

ok, i was just thinking maybe better conduction to the source of ground directly would do something. I was thinking of it in terms of like connecting a block of steel in between 2 copper wires where the current needs to get from one end to the other.

Why would you put steel BETWEEN 2 copper wires?
Why not join the copper wires with copper?

If you mean that the steel is the chassis, then why not use the steel (chassis) if it has less resistance than the copper cable(s)?

I have a question. I have a 2008 Chevy HHR LT2. I've installed 2 amps , a Rockford P3, Alpine door speakers, and an Eclispe Hu. Since the amps are in the tray above the spare, and the freakin battery is right below the tray next to the spare, does anyone suggest that I ground to the chassis instead of the battery?

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"That'll get ya 10 in Leavenworth,11 in Twelveworth, or 5 & 10 in Woolworth". Groucho Marx                                                      

I hope not.

Unless for "absolute ground" arguments when the amp's peak power consumption is below the alternator output (fast response of course!) and the priority is when the vehicle is running/charging.

But excluding ground loop issues, I'd probably do both (based on having both sources as well as connection redundancy).

Old Spark, thanks for your insight. I've owned several GM vehicles over the past 30 odd years, and noise has been an issue in 99% of the cases where I removed the OEM audio and went with an aftermarket  HU, amp(s), better speakers, ect.  In each case, I had to go back to the negative on the battery, or the engine block, double ground the HU, or some combination of things. Going back to the battery has had added benifits also. I've not had any severe case of headlight dimming, and I've always run a mono sub amp of at least 500 watts rms. With my current system, the stock battery and stock alternator work just fine, and my Kenwood mono will max @ 900 watts rms ( I DO NOT have the gain set that high though ! ) My son has an 08 Cobalt set up basically the same way (since the battery is next to the spare. I just had to build him a rack to go in the trunk. Each manufactuer has it's quirks, and I believe Dodge/Chrysler to be the worst I've ever dealt with. But as they say "Live & Learn"

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"That'll get ya 10 in Leavenworth,11 in Twelveworth, or 5 & 10 in Woolworth". Groucho Marx                                                      

Thanks for the thanks mrarff.

It's interesting that I have never had noise problems.
BUT - my newest "on road" car is vintage 1969 (though I do own modern cars - eg, a 1990 4WD). My current "temporary vehicle for the next 12 months" is vintage 1965 that I have been driving for 10 years....
[ But hey - I upgraded its generator (yes - a commutator and high-current isolation relay!!) to a modern combined alternator/regulator - I'm not that stupid! ]

{But also...} I have never fitted additional amps etc - standard systems have been loud enough. (Yes - I suffer tinnitus, but my vehicle noise is conversational noise else a balance of road noise and sound-system noise. I often rely on sound to inform me of excessive speed or RPM.)


But my audio has ALWAYS had dedicated feeds to the battery: +ve & -ve.
That's probably because I know the battery is a "big cap" that filters much noise.
Plus I reckon my cables will be better than OEM power and speaker wires that are part of a loom... and in my case, mono! (To think that I used to run speakers through coax! But that was back in LF CB radio days.)

Dedicated power also meant no "ground loops"(sic?) if shared with others power consumers. [I sic ground loops because that alleged noise does not always involve a loop per se - at least not in MY [i[traditional way of thinking of "AC induced" noise in wiring ground/shield loops.   Dear Eddy.... ]

But I recognise that with my "all in one" sound and amplification, there is no external shield/ground path.
Not that it should matter with low power, but with the continued STUPID practice of making heaps of money by distributing 12V DC for hi-power sound systems, hey - of course noise will be an issue.
But there is a $$$$olution for that....


Now there are new factors to take advantage of....
HIDs should overcome dimming. (IE - whether 8V or 16V should NOT effect HID brightness - unless it's cheap converter! But I can sell you a better one....).


As for the rest of us, conventional headlights should be powered from the alternator. Hence if your audio is battery connected, the inter-wiring will help isolate the surges of either.

And now that many know the "the Big 3" issues.


You have solved so many audio issues with the battery next to the amp. (And saved the expense of a cap - the Darwin Awards lose yet another entrant!)


Alas too many buts in this reply - me being the worst butt.
I'd better exit now. (Yes, another butt joke.)

Thanks Old Spark, that is an interesting take on things.Have a great one!

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"That'll get ya 10 in Leavenworth,11 in Twelveworth, or 5 & 10 in Woolworth". Groucho Marx