Conductivity of Steel vs Copper. Grounding Question.

 

Silver Member
Username: Fandim

Reno, Nevada United State...

Post Number: 183
Registered: Jun-05
I was reading some stereo config articles, seeing if there was anything I could do to fine-tune my system, and I came across something saying that it's better to run a second length of wire, equal to that of your power wire, back to the battery??

They say the justification for this, is copper is a LOT more conductive than steel, and by grounding to the chasis, that the ground faces a lot more resistance because of the steel, rather than simply having it flow back through copper wire.

Is there ANY truth to this..? I'm not an electrician, but do know a fair amount about the subject, etc... It seems logical, then again, I dont know enough to actually assume without asking that it would indeed be better..

I know that using aluminum wire, instead of copper, that you should go a size bigger wire..Since the flow of electricity is less through aluminum due to resistance... So using a bigger wire compensates...

But...using that type of thinking... There sure is a lot of steel Chasis for electricity to flow through, so is this why the less ground wire the better? Since it can actually flow through the chasis easier than wiring, due to the amount of steel available, even with a higher resistance?

Seth
 

Platinum Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 10487
Registered: Dec-03
most modern cars use a unibody chassis without an actual full frame, and they use spot welds to hold the car together, so the result is that your chassis is about equal to 4AWG stranded copper when you're talking about conductivity and current flow. If you have an older car it can be a different story.
A lot really depends on the car itself, and how much current you plan to draw through the wire. If you're using 0AWG, yah I'd run dedicated lines for ground and power in most newer cars.
I'd do the same thing if I were planning to run a highly modified charging system, like HO alternator, isolator, and battery banks.

For the average street car stereo system though, chassis grounds are just fine, and while steel may have a higher resistance than copper, remember you have a lot more steel there so you've got to compare both surface area and resistance or conductivity to compare two materials side by side that way.
 

Silver Member
Username: Fandim

Reno, Nevada United State...

Post Number: 184
Registered: Jun-05
Yeah...that's what I was thinking, with the amount of steel, etc. My car is a 99 firebird.. So not sure how much of it is steel, lol.. And I'm actually running a pair of yellow tops, about 15 feet of 0 gauge from front battery to rear battery..(isolated rear) then a couple feet more of 0 gauge, (about 2 feet going to a 20f cap, and 2 feet going to a d-block) then it splits into 4's from there. Pulling about 3.5 Kw rms.. Do you recomend using a 0 gauge ran from the neg batt terminal to neg batt terminal, or can I just put the 2nd batts ground to the chasis? Also, should I use ANY chasis grounds at all, if I do run a 2nd 0awg back to the 2nd battery, or should I just get a large d-block and run all grounds directly to the negative posts on the optima?
 

Platinum Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 10516
Registered: Dec-03
that's up to you.
 

Silver Member
Username: Fandim

Reno, Nevada United State...

Post Number: 186
Registered: Jun-05
GlassWolf, would there be any disadvantages whatsoever in doing both? I.E. running a 0 gauge negative to the back, attaching it to the negative side-post of the 2nd optima, then using a terminal with dual 0awg outs, attaching one to a cap/d-block, and grounding it from there, and the other to the chasis?
 

Silver Member
Username: Fandim

Reno, Nevada United State...

Post Number: 187
Registered: Jun-05
Bleh, let me re-say that. Fingers were going faster than my brain.

From the 2nd battery (with 0 awg from front battery attached to side terminal), using a dual 0awg output on the top connector, and running one of the wires to a capacitor with 1 input/3 outputs, and grounding one of the outputs from that to the chasis...and running the other to a solo 0awg / four 4awg connection d-block, and ground my amps to that with 4 gauge..

Any disadvantage to this?
 

Platinum Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 10535
Registered: Dec-03
keep it simple. you want to run as little wire as possible. avoids ground loops and avoids EMI/RFI induction.
if you want to use 0AWG throughout, just use a d-block to ground the amplifiers universally from the dedicated battery's negative terminal.
then run 0AWG for both pos and negative to the front.

diagram it on paper.
see how you can wire it to keep it as simple as possible.
the shorter and more simple it is, the better off you'll be.
 

Silver Member
Username: Fandim

Reno, Nevada United State...

Post Number: 194
Registered: Jun-05
Thank you for your advice, Glasswolf. Not going to pretend to know more, or even close to the amount you do on this subject..So I will be taking your advice, and running a dedicated 0awg for both power and ground.

Another question - Since the majority of draw from my system will be from the back of the car, would it be better to ground my back battery to the chasis (Like I would normally do to theone under the hood), And d-block all the amp grounds etc to that battery, and not ground the one under the hood to the chasis, instead letting it ground through the 0awg to the 2nd batt? In turn making all of the amps grounds drastically shorter, while avoiding any ground loops?
« Previous Thread Next Thread »



Main Forums

Today's Posts

Forum Help

Follow Us