I wouldnt agree with that, really. I'm running some kolossus 0awg back dedicated for my ground (as well as power) to a dist block close to my amps, then running 4awg to my amps, and it works well.
In the case of running seperate grounds, all it is, is like using your chassis as a dist block.
noone ever said it wouldnt work Seth. Ichoose to separate the grounds but some installers choose to run them to the same point. If you choose to run your ground wires to one point you can also use a distribution block. If you do not use a distribution block then you will want to stack you ground wires so that the largest current carrying wire (usually from your largest amplifier) is on the bottom (closest to the ground point) and that your smallest current carrying wire is on the top (closest to the head of your grounding screw). The proper way to do it is two seperate grounds, will it work with a distr? sure it will but there is more chance for error.
Heh - but the fact remains, the cars chassis is still acting like a big dist block.. it's the common metal that you have as the point connecting to your batteries ground. And a cars chassis can be a big choke point for a ground.. most cars chassis only conduct about as well as a 0 gauge wire - whereas in multi kilowatt apps, you need more than a 0 gauge conductor.
Here's the little example of how a cars chassis is just acting like a dist block..
Do NOT do pic b. Use the same frame rail. 2 words, ground loop.
You may do w/e. I would not use a distro block. Connect from the amp, directly to frame. If you need to go from 1/0 to 4g, ill sell you a stinger adapter i have laying around. I highly advise against ANY unecessary extra connection involving ground. One loose connect could cost you an amp, or possibly the HU's outputs when the amp grounds thru the RCA's.
Thing remains - a lot of high powered setups, need more ground metal than the average car chassis provides. Steel is not very conductive at all. as well - a distribution block can provide a better ground - and easier, as far as being more secure, etc - and definitely no need to worry about sanding, and having a clean ground - for most people.
However - keep in mind - in my example, the dist block is coming from a dedicated ground wire running to the back, NOT a dist block going to the chassis.
Measure you output voltage from your battery with the car off. The average will be arounnd 12.6v. Now, probe the frame of your car with a digital multimeter. Find a good spot that has no voltage drop across it. Some places might have 12.3v, 11.6v, 11.1v etc etc etc, dont use those. Find a spot that reads 12.6 volts like the front battery, then scrap all paint from the metal and use a bolt w/nut and washer. If you cannot find a spot that has no voltage drop, i would just run a wire back to the battery as stated. Why would that not be my first coice? The battery grounds to the same frame you are. With how much wire? 12" or less. How much ground should your amp have? 12' or less. Grounding to the battery increases your ground to 15ft or more, PLUS, the length of ground to frame from the battery. If the battery grounded frame isnt good enough, then why is grounding to the battery (which is ground to the frame) better?
The ground wire being more than 18"? yes. But what do you think your chassis is? It's acting as the 'ground wire', and is made of a less conductive metal than power wire - and goes nearly the same distance as a dedicated ground from your battery.
So sure, 16 feet of 0 gauge copper wire, or 16 feet of steel, that's often spot welded in places in the vehicle. hmmm... Even without the spot welds..
[quote]PLUS, the length of ground to frame from the battery. If the battery grounded frame isnt good enough, then why is grounding to the battery (which is ground to the frame) better? [/quote]
Because - you arent using the batteries ground to the frame is this example. It'd have it's own ground straight to the battery. The only reason your battery would need to be grounded to your frame at all in this example, is because that's what your other car electronics were grounded to.
You could disconnect entirely the ground to chassis from the battery (assuming you wired your decks ground to the dist block or battery) and your audio system would still work if you had a way of turning yoru HU on (i.e. a switch)
So the battery to chassis wire has nothing at all to do with your audio systems performance if you're using a dedicated ground to run back to it. This is also effectively upgrading the battery to chassis part of the big 3, or actually bypassing it altogether.
Yes - renegade. The battery grounding up front, is effectively making the chassis a wire to the back, which is why grounding to the chassis works as a ground. If you connected all your cars electronics directly to the dist block going to your batteries neg terminal - you wouldnt need to use your chassis at all to begin with. It's just a conductor that acts like a big wire is all.
Would you rather have, an 18" copper wire, going then to 13 feet of steel, then to 18" of copper wire, totalling 16 feet (13 of which is a much less conductive metal than copper), or like 17 feet of copper wire? And guaranteed not to have any welds, or non-solid pieces?
The *average* car chassis is a little less conductive than a 0 gauge copper wire. Your whole test, about using a voltage meter, and finding a place in the back to ground it - where there is no voltage drop - is flawed.
Why? Because Even a small wire will have no voltage drop over a long distance, if the amount of power is low. However, when you're drawing a much larger amount of power, through the same size wire, you're going to have massive voltage drops.
In very high amperage-pulling situations, since a car is DC - you need a ground just as large as your power wire. So if you require 0 gauge power wire, or even larger - then your cars chassis is actually going to be the choke point of your power to the amplifiers.
Also remember - using your chassis - you're sharing the batteries ground wire to chassis, with everything else electrical in the car.
That's why people recommend upgrading (part of the big 3) your bat to ground wire, so the small wire (usually 8 gauge, sometimes 4, stock) thats originally there, isnt providing mucho resistance, as power consumption grows.
Renegade - if you've been an installer for 12 years, you should know that with a voltage meter on your battery, grounding it to someplace in the back of your vehicles chassis - that almost ALL spots are going to read as 12.6 volts with the car off, because of the very small amount of power the voltage meter is using. The voltage drop increases drastically, as power consumption grows across the same size wire.
(I.E. Sending 10 amps across a 20 foot long 4 gauge wire, you wont have voltage loss, send 15 amps, and you're talking about a large voltage drop seen)
Troy, what my point is.. Your cars chassis can only conduct so much, too. It's (on average depending the vehicle, and length etc) slightly less conductive than 0 gauge wire, foot for foot.
So lets say you needed to run a 10,000 watt application, like in your example. You'd need several strands of 0 gauge wire, or welding wire, etc, for your power wire.
Ok, great. But your cars chassis, is still only acting like one 0 gauge wire, whereas you need several. (Remember - your ground has to be just as big as your power wire.) So if you did not run dedicated ground wires back, too... Your chassis would be a huge choke point, because the power wires can only draw - as much as the ground wires (or in this case chassis) can carry, too.
Like here, in this example, all the upgraded wiring would be hindered drastically due to using the chassis as a ground.
so if i run 0 guage to the back, and distro it to 2 4 guages one for each amp... do i ground each amp to the same spot (where the one i have now currently is, and works fine), do i ground each amp to a different spot, or can i run a distro block and make the 2 4guage grounds 0 guage....
Personally, I dont even run an upgraded ground wire from my engine, to my chassis. I did my upgraded ground, straight from the alternator to a dist block that splits to my amps, and battery directly.. (This bypasses the need for the alternator to ground through the engine, then to the chassis, then to the upgraded wire you put for your battery to chassis) So basically cuts out the steps of grounding through the engine/ground strap/chassis, and goes straight to the point.
My + wires, I have my alt going to a dist block about 12" away from it. From there, I'm running 0 gauge up to my battery, and 0 gauge from the block back to my amps. This way, I dont have to run wire up to my battery, then go from my battery doubling back up passed my alt back to my amps..
