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

I hope you were joking or just had a quick question, cause that shit would take forever.

 

With all due respect but some of your statements couldn't be further from the truth:

1. The battery's negative terminal is not only connected to the chassis but if you look closely there is one big gauge wire, this one goes to the starter motor housing or very near it and the second smaller gauge one goes directly to the chassis, this is one of the reasons is not a good idea to connect your winch to the chassis ground!! Because this wire can not handle the winch current plus all the other car accessories. Also you really don't want this amount of current flowing from your bumper/chassis to your battery, so do it directly to the battery with the appropriate gauge cable like is recommended by the manufacturer.

2. While there are multiple ground connections made, the same ground points are used for any given sub-assembly. For example, there are no separate grounding points for each headlight. Indeed, they're common. Another way to look at this is, if power for more than one device comes from the same supply point (relay, switch, battery, etc.), then the grounds for those devices should also be common. In case you missed the point, this is to lessen any potential for a ground loop. So really is not a good practice to just connect your ground to "any" point in the chassis.

3. Just because the chassis is the thickest wire doesn't mean is the best, wire material is very important, one reason manufacturers use copper, it's a better conductor than other metals.

4. Not really. If you cause a potential to appear between two factory ground points (e.g., ground lead to a seat frame, positive lead to the battery), the resulting ground loop may manifest itself as an RFI problem. This is especially important when high currents are involved (amplifier use on a HAM or maybe even CB radio, or a winch for example). Just read your radio manual and you will see that they recommend to connect directly to the battery terminals with a fuse, there is a reason for this and I'm sure is not so they can sell more wire.

So really most applications not only are direct battery connections necessary, adequate sized conductors and fuses are also required. Again check and follow your manufacturer's recommendations for your piece of equipment.

 

So verdulken, is it better to ground stuff to the frame unless it's high current draw or close to the battery? Is there a problem grounding stuff directly to the battery if the wire is large enough or short enough to remedy any voltage drop?

 

Yeah there is no problem grounding stuff to the chassis, like the previous guy posted a lot of the accessories are grounded to chassis. And no, there should be no problem connecting a device directly to the battery, especially if it's close enough and the correct wire is used. I would follow your device's recommendation, for instance I have a CB and a HAM radio, I can't recall on the CB but for sure on my HAM radio it specifically calls for the device to be connected directly to the battery to reduce noise and because it can draw up to 7 amps when in full power mode. Could I've connected it another way, yes but they provided enough cable so no big deal. Also as an example I have my off road lights grounded to chassis, it works too.

 

They aren't. I ran my winch neg cable right to the frame which was about 18 inches from the winch.

 

I recall a post where a guy had grounded his winch to the bumper plate, or body, I forget which.
Anyway, on his first use of the winch, his rear brake lines burned up. Any comments on how that would happen?

 

With all due respect then, read my full statements because what you just outlined was addressed in this statement.

Thus, with that one statement I just addressed the problem you outlined by stating that you need to increase the thickness of that wire that runs from the battery to the chassis to avoid that problem. Please see "The Big 3" wiring upgrade for further information.

Good valid point, but it doesn't apply to the single winch grounding that was being discussed and it certainly doesn't apply to audio components, since the goal for audio components is to make your grounds "common" between components that get inter-connected to each other. Thus, running a long copper wire connected to the battery terminal to an amplifier's ground terminal in the rear of the vehicle would make that ground on the amp uncommon to the radio ground, which is connected to the chassis and would additionally make two very uncommon grounds if the metal case of the amp is mounted to the chassis also, thus introducing ground noise into your audio system. Thus, the reason why it is always recommended to run as short and thick as possible of a wire from the ground terminal of an amp directly to the chassis, quite similar to what the OP was asking about.

Good valid point also, but you left out the other half of the equation of conduction which is the increased thickness (area to be technically correct) I mentioned, over that of the copper wire. Thus, you can't really make a contradictory point on conduction by only focusing on half of the equation for conduction.


The key here is "common" ground and by your own previous definitions of copper vs. steal and conductivity you just made them "uncommon" grounds since the majority of electronics in your vehicle are grounded through the steal chassis, thus you just increased the differential voltage between the grounding points attached to the separate copper wire and the steal chassis connection point.


Yes another very good valid point....fuses are required on the POSITIVE wire path side which was not part of what was being discussed in regards to grounding.

 

Amazingly my Jeep starts everyday, aux. lights work, the winch works...

 

Good Call. I think you realize hairs are starting to be split.

 

You got it - everybody relax - it's a short week anyhoo!