Ground loop?

[smd4life 5,000+ posts]

ive heard that the best ground on a car is the bolt that connects the alternator to the block of your motor strait to your amp completing a ground loop just wanted to see what kind of responses i would get ive heard that it's best torun an undisturbed wire from the amp to the alt and then brantching that wire off somewhere near the amp with a split bolt connector

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[houston281 10+ year member]

hahahaha thats a bunch of crap,LoL.the best ground on a car is the frame itself,remember keep the ground wire the same guage as ur power wire and the shorter the better,dont forget to scrape the paint away when you ground it.

 

[johnecon2001 5,000+ posts]

hahahaha thats a bunch of crap,LoL.the best ground on a car is the frame itself,remember keep the ground wire the same guage as ur power wire and the shorter the better,dont forget to scrape the paint away when you ground it.

//content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif the best ground is the battery Negative post. //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[houston281 10+ year member]

ok, let me ask u this.according to MECP,the shorter the ground the better.also,if you look in the spec sheets amps come with,it says dont mount amp in engine compartment.so are you gonna run a ground wire the same as your power wire?are all the other grounds on the car as for the whole electrical system ran to the battery?NO.the frame is the chassis ground.

 

[canadian_mofo 10+ year member]

grounding it to say the inside metal wall of my truck cab would be a good ground too right? As long as ive gotten rid of all the paint around it?

 

[smd4life 5,000+ posts]

youre right but it doesn't mean thats the best it means that thats the cheapest way to ground whatever youre grounding

 

[smd4life 5,000+ posts]

the guy that told me is the owner of true bass solutions he designed my box and my speakers he said he has studied and studied the voltage drop at the amp and out of all all grounds in the car that one had the least amount of voltage drop

 

[smd4life 5,000+ posts]

ok now that thats out of the way let me say this in the big 3 you connect the alt to the frame so by this you connect the ground from the amp to the alt through the frame

im asking if its better, not cheaper or less work, better to do this through an undisturbed wire

 

[forbidden 10+ year member]

So the chassis is the ground is it? What happens when the day comes that a chassis is no longer metal? A chassis can not be ground UNLESS a ground wire is attached to it from the battery. Not too hard to understand.

According to MECP, I must have a certificate to be a installer. What about those of us that were trained 15 years before MECP was even in existence? MECP for the most part is doing this, you pay them, they do the Jedi Mind Trick to you, you get piece of paper that is totally worthless but looks good on a wall.

FYI, a good ground is not about the amount of metal in the return to the battery. It is about the combined resistance through it. With unibody cars that are a combination of glued together panels, crappy spot welds and blended metals, most of them are a horrible high resistance return to the battery. This is simple, electricity is an algebra equation, what you do to one side, you must do to the other. If you want to draw 100 amps of current and you have a build up of resistance on the ground, what do you think is going to happen to that amp in time? A good ground is one that is as low in return resistance as possible and is not always the chassis. If a amps manual also told you that jumping off of a bridge would not kill you, would you believe them and run out and do it or would you consider the fact that their info just might not be accurate?

 

[joetama 5,000+ posts]

You develop more of a voltage difference running a cable from under the hood of your car to the amp than directly connecting the ground to the frame. And if you have the ol' big 3 properly installed then the frame should be the lowest point of ground all over the vehicle. All of your grounds should run to the same place or you can develop voltage differences that will cause background noise.

 

[helotaxi 5,000+ posts]

You develop more of a voltage difference running a cable from under the hood of your car to the amp than directly connecting the ground to the frame. And if you have the ol' big 3 properly installed then the frame should be the lowest point of ground all over the vehicle. All of your grounds should run to the same place or you can develop voltage differences that will cause background noise.

Manville Smith of JL audio did some very extensive testing of chassis grounds on different vehicles. He found that on most unibody cars using the car sheetmetal in for your amp ground with a trunk mounted amp and the amp grounded next to the amp the resistance between that ground and the battery was equivalent to a single run of 4 ga wire. If your amps (all of them total) are drawing more power than you would supply with 4ga, then using the sheetmetal as a ground is a chokepoint in the current delivery path. In a unibody car (basically anything that isn't a truck, SUV or van built on a ladder frame) your best ground is going to be a large gauge wire running back to the battery. In a vehicle with an actual frame you can ground to the frame, not the sheetmetal and get a very low potential ground. For this to be applicable, you have to ground the alt/engine block similarly to complete the path with the alt and be able to get max current with min voltage drop from the alt.

The basic rule I would put forward is that if you are building a system in a unibody car and your primary power wire from the battery to the amp is larger than 4ga, you should strongly consider running an equal sized cable back to the battery neg terminal or the battery ground point.

 

[forbidden 10+ year member]

^^^^ I agree with this. This is right back to the quality and capability of the installer and the shop that you go to. I always measure the return resistance on the vehicles I work on (after blowing a old Rockford Power1000 4 times over, this was found to be the culprit). So even a veteran installer can learn something new and adapt into how business is done.

 

[joetama 5,000+ posts]

Interesting, I do see that point, but if you have the ladder frame it's still better to mount it to the frame, simply because it will give you the lowest point with out having extra capacitance and inductance from the cable which will give you extra unnecessary ground resonance.

Grounding is just one of those subjects that have its own little camps of thought, and each camp wants to shell the other camp with artillery lol….

 

[forbidden 10+ year member]

Which means that one should always check each and every vehicle that comes into the bay and do the right job for the application, this keeps the artillery at bay.

 

[joetama 5,000+ posts]

LOL, agreed....