I've heard over and over when running power for something in an automobile the ground should always be bonded to the metal chassis as close to the device as practical. My questions are why is it better to be close and why not run the ground to the battery?

 

When you have a floating ground it is best to ground like devices as close to each other as possible, at least that is my understanding. The closer the grounds are to each other the less likely chance of having a impedance mismatch which in turn is less likely to induce unwanted noise...

 

Well I don't claim to know a great deal about 12v wiring on automobiles, but I have been told that the ground/negative is equally as important as the positive, so I do run my grounds back to a main grounding block, and always with a more than adequate gauge wire. Especially on hi amp draw items. Wire is cheap. I find it so frustrating to try and trace out a bad ground if it is just run to a ground screw somewhere. As a result I do not have ground issues. Just my opinion.

 

This is good advice. When we first learn about electricity in school, we are taught that current flows from positive to negative. Then we find out that the opposite is true. And in this case, it's a good idea to have ground wires that can handle dishing out that current.

 

The reasons are as followed:
1. The Negative Terminal of the battery is connected directly to the chassis.
2. Every other electronic in your vehicle that needs a NEG GROUND connection is tied directly to the chassis....not the NEG terminal.
3. The Chassis is the thickest wire in the vehicle....you can not buy wire that is thicker than the frame and engine block of your vehicle. So not only is buying a long 0 Gauge Ground cable to run from the back of your vehicle to the Neg terminal of your battery a waste of money, it gives you more impedance than if you had taken a small piece of that same wire and connected it directly to your chassis with the smallest length run of that wire.
4. Running Long Ground wires directly to the Neg terminal increases the likelihood of there being voltage differentials between that ground wire and the chassis ground, thus creating hum situations in audio components and potential for getting electrical shock when you touch metal objects.

If you want to increase the strength of the ground in your vehicle, running a wire from the NEG terminal, directly to the electronic device is NOT the answer. The answer is to increase the thickness of the wire that connects from your NEG battery terminal that connects to the chassis.

When you start to think in the correct terms that your vehicle is one thick ass ground wire of metal, then making short wire runs to the chassis or that thick ass wire will all start to make sense.

 

Why then are all winches hooked up to the battery, both + and -, and not grounded to the winch mount platform, which is some big ass metal, and just the + to the battery?

 

Most likely to make the winch install universal and more error proof. A winch is not an audio component where ground noise introduced by connecting it to different electronic components becomes a problem for a winch.

Additionally, there are plenty of winch installs out there where the ground wire is not run directly to the NEG terminal. In those instances, you have to make sure additional wiring is ran from the NEG terminal of the battery to the chassis and additionally make sure a proper connection from the winch NEG connection to the chassis is made and there is no obstruction by any paint or corrosion when connecting that wire to the chassis. Thus, running an adequately thick enough wire directly from the winch NEG connection to the Battery Neg terminal eliminates those concerns, thus simplifying the install so that any dummy can do it, and do it in any vehicle without knowing anything about that particular vehicle's ground path from the battery Neg terminal to the Chassis.

 

So I can just cut of the negative cable from my winch and hook it right up to the winch mount itself. That's great, thank you.

 

Ground wires should not be any lo get than 18 inches.

 

That is a great explanation and suddenly the light in my head goes "on" (but without a ground wire). Just by my dumb luck I had grounded my Warn winch to the chassis rather than the battery.

Now, can you explain AC current to me, as I still don't get it?