The ground for the amplifier should be directly to a bare metal area of the car body, within eighteen inches of the amp's location. The ground wire should be the same gauge as the power wire.

* The best method for attaching the ground wire to the car body is to find a convenient location as close to the amp as possible. An existing bolt or screw can be used secure the ground wire terminal directly to the metal body of the car, or a self-tapping screw can be addded. It is recommended that you use sandpaper to remove any paint that may be covering the ground point, so as to give direct contact to the metal of the body.

* Always use a ring terminal crimped or soldered to the end of the ground wire, and not just bare wire.

* If it becomes necessary to drill a hole to accept the ground screw, take care NOT to drill into the gas tank, gas line, or brake lines.

* To reduce the likelyhood of noise, avoid mounting the amplifier chassis directly to the vehicle body. Instead, mount the amp to an electrically insulated material such as a wooden board, carpeted area, or plastic surface.

A few other things: A car chassis is about equivalent to a 4 AWG cable. If you are running large amounts of current, IE if your power wire is larger than 4 gauge (thicker), then it might be a better idea to run a seperate ground cable back to the battery for best performance. Also, if you do use the chassis ground, make sure the ground wire between the alternator and the amps is at least as thick as your power cable.

Hi sectrix, hello everyone,


Sounds pessimistic to me. My experience says, at least 00.

Regards, Norm

I would agree with Norm here, but wouldnt the ground be as good as the ground cable to the battery? Or am I thinking too hard?

Hi andrewk, welcome back.


Yes, cables are the weak links.


Chassis ground using a wire to the alternator?


I thought Brandos post covered it very well.

I prefer soldered connections for sound systems, but crimped work just fine.

Regards, Norm

I will back up Brando, Andrew and Norm here....since your battery grounds to the chassis (well OK most likely the engine - same difference its chassis ground) it would stand to reason that grounding directly to the chassis makes most sense. I personally have never seen someone route a negative battery cable from an amp(s) back to the battery {can't imagine why you'd want to either} perhaps if the battery was trunk mounted and within 18 inches of the amp(s), even then I think I'd prefer a chassis ground...myself, I've usually found a nice solid piece of metal (like the brackets for the trunk hinges), test it for a good ground and make sure it will not cause interference with operation, tap a hole, sand around it and stick a stainless bolt with some nice large washers (on both sides of my mounting hole)/nylon lock nuts to keep it from working loose. (Now you have a post in the trunk good for any other grounding that may come up later)

Interesting post, considering its timing.

Honestly I think it is better to have a bigger ground than power wire, only because if there is a serge for some reason the power can escape with ease. Maybe I am being to cautious but when you have put so much time and money into a system you tend to be

Another resurrection of this one has been overdue, for a couple of years.


Assuming your "surge" actually reached the system, wouldn't a larger ground wire exacerbate its effects?

Isn't the purpose of a fused power supply, to stop your "surge" from even entering the system?

Norm

Yeah, I am sorry about the spelling, was never my strong point. No the ground wire would not make the surge worse. Also depending on what amp fuse you have it could still go through. It is more of a caution then something that is going to affect the amp every day. Say either you have the wrong fuse for some reason (hopefully not) or the fuse is defective, a ground wire which is bigger would let more power out at once, thus causing less power in the amp to blow it. It is not a replacement for the fuse but it helps. Its almost like a cap. Lot of power in at a slow pace with a large discharge.

Your logic is interesting....but doesn't apply to any real world application that I know of.

Taking an amplifier for example, it will only draw as much current as it needs. The only "surge" of current would be if the amplifier was doing something it wasn't designed to do. It is possible to have a voltage spike, such as if the regulator in the alternator was at fault--but a larger ground wire nor a fuse would do any good to save it. Well, actually the fuse would blow eventually--whether it's before or after internal damage is done is hard to say, but usually after internal damage occurs.
That's if the voltage spiked rather high...say around 20v, power supply capacitors in an amplifier are usually rated around 16v and can't handle the excess voltage...they would fail, most likely short out and blow a fuse or two.

Anyways...that was going on a lot of assumptions there.
www.bcae1.com
There's a great site, I suggest reading up on voltage, current, fuses...etc.

Having a bigger ground than power wire sounds like your explaining a fusible link....just a really long fusible link (not recommended).

"Lot of power in at a slow pace with a large discharge."

It's output is only as fast as it's input. That's why a lot of people (including me) do what has been termed the "big 3".
I have a 0 gauge power wire going to my amplifiers. The stock battery ground to chassis looked to be about a 10 gauge wire. The amplifiers are grounded to the chassis. The alternator power wire looked to be about 8 gauge. The alternator is grounded through the engine, which is grounded to the battery via an 8 gauge wire.
I upgraded the battery ground to chassis to 0 gauge, alternator power wire to 0 gauge, and engine to chassis ground to 0 gauge (plan to do an engine to battery ground as well).
Doing this wiring actually raised my voltage to a normal 14.5 volts. It would get as low as 13.5 or so at times...not anymore.
Again, It's output is only as fast as it's input....I decreased the resistance on my grounds and alternator power output.

TOC Admin
Brando

I see, Well I am going off of what I have been told by what I thought was good sources. Also you said your batt runs at 14.4, mine does too but I am pretty sure it is stock wires, alt, and I know it has an upgraded batt but its not anything like a yellow top. I just was wondering if you think a 140 amp alt would be good enough to hold a kicker sx 1250.1 mono block. My lights dim but not too horribly. I have 0 gauge wire for power and my batt is only about 4 feet from my amp as to having my batt under my back seat.

I know the battery is under the seat in those cars..I've never really looked how big the charging wire coming from the alternator is...but I bet it would be worth upgrading that wire. Upgrade the battery ground to chassis wire, as well as engine to chassis ground. It's cheaper than getting a new alternator...see how the stock alternator does with these upgrades first.

TOC Admin
Brando

well i got a cap from my cuz for free, is 8 fraud and no dims. so that fixes that problem lol but now i blew my 100 amp fuse, was wondering what fuse size i should use with the kicker sx 1250.1 amp, runs at about 1500 rms even though its rated at 1250, as some may know thats common on kicker amps.

http://www.sonicelectronix.com/item_150 ... 250.1.html

Looking at that page, it appears that your amp comes with a 150 amp fuse and fuse holder. So I would use that...if that's the only amp you have.

Was it blowing the fuse before you added that cap?

TOC Admin
Brando