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  • Grounding kit in cars

    Calling oldspark, or anyone else with extensive electrical knowledge.
    Grounding kits of sorts seem to be a big thing in car audio circles as well as car tinkerers. Audio circles say it improves the sound, and car tinkerers say the same thing as well as improves other things.
    Here are my issues that I'd like answers for that nobody seems to state, and only regurgitates principles of the need for larger return path.
    1/ the general principle seems to be providing a bigger gauge wire for a better return. However, the bigger gauge wire is always picking up from a smaller wire. A 14-16gauge wire going to a 4gauge to a grounding point. This doesn't make sense to me. If this was really suppose to do something, I would think the 4gauge would HAVE to be coming directly from the source and not have an intimidiary wire in between. That to me defeats the purpose. Like taking a 2" diameter pipe and feed that into a 15" diameter pipe, it doesn't change the amount or force of water coming out the 15" as was coming out the 2". So why? How exactly does this help? I can see changing the wire from from the battery, because I have access to replace or add the new wire on top, but all the other dozens of grounding wires, I don't see the point of adding the grounding kit to them.
    2/ My audio and computer stuff is independently grounded with a 4gauge in the back already, however I'm still told that I should hook up a grounding kit in the engine. Why does the grounding in the engine affect an independently grounded system, if my return path isn't going back to the battery?

  • #2
    Increasing only part of a wire gauge reduces resistance.
    It does in a water pipe too, but not as much as with electricity - that's one instance where the water model/analogy isn't that good.

    But when talking about grounding kits as in the big 3 etc you replace the engine/chassis/battery grounds with fatter wires, or add extra wires. (Adding extra independent cables/wires/straps is better because (1) it does not impact warranties & (2) provides redundancy.)

    In general those big-3 grounds are the most or VERY important because a bad ground can blow electronics. VIZ some vehicle that blew $thousands of equipment (7 DVD screens etc) which I suspect was due to a poor or broken engine to chassis/body GND or similar.

    FYI - as I recently wrote on, vehicle GNDs are usually battery- to engine (mainly for the startermotor), and battery- to chassis/body (that's TWO grounds to inter-ground those 3 vehicle components), however the latter could be engine to chassis/body instead, or that engine-chassis/body could be added to provide redundancy or reduce overall ground resistance.
    Incidentally that shows one ambiguity - I regarded the BIG-3 as including the +12V (eg, alternator to battery or battery to +12V system etc) but apparently it meant having 3 grounds (battery- engine chassis/body).

    You are not wrong in your thinking, but if talking big-3 type grounding kits, they are to ensure SOLID grounding between engine & battery and "the vehicle system" (body etc).

    Equipment grounding IMO is essentially a separate issue. F.ex even with solid ground bonding you might still take power & GND straight from the battery. And then wanting a "common ground point" (to avoid ground loops or differentials) might mean other GNDs are also from the battery.
    Usually a chassis point is chosen for a common & compromise GND point since (1) it's difficult mounting a lot of GNDs on the batt- terminal; (2) engine or alternator grounding means vibration & heat (increased resistance & breakdown) and similar crowding or mounting difficulties, & (3) it provides a compromise mid-point ground (for those that talk about the battery or alternator being the "absolute ground").

    I discussed the above on the12volt's 2011 jeep liberty big three wire upgrade (page 2).
    Last edited by OldSpark; 02-20-2014, 11:22 AM.


    • #3
      Ok, I understand the big 3, that makes sense to me, what about things like this
      Where people make there engine into a spider web of grounding wires to take all the grounding points on the body and engine back to the negative terminal of the battery? Does that make sense? And isn't that a definite recipe for ground loops?


      • #4
        I will add a couple things to what OS said...

        But I will start by stating my experience is with the same basic style wiring scheme so if another vehicle uses a different style it is something I have not experienced.

        And since I have only dealt with GM vehicles this would make sense to me...

        For the Positive lead I have seen two different types of setups for the main wire. I have seen the large wire go from the battery to the starter and then from the starter to the main vehicle power bus for one style and the other style had two large wires coming from the battery terminal with one going to the starter and the other going to the main vehicle power bus. But BOTH systems had a small (10 or 8 gauge) wire from the battery to the alternator. The larger wire I have seen was a 6 gauge wire. In these configurations it would seem to be accurate to assume the systems are designed to run the car from the battery and any large surges will pull from the battery and not the alternator. So never try running the vehicle just off the alternator because not only do you not have the filtering capacity of the battery but any large start up surges could burn up the small gauge wire.

        For Negative feeds on my vehicles I have only seen 1 type. A main wire runs from the battery to the engine block. There are engine grounding straps running from the back of the engine block to the frame on the vehicle.

        So when upgrading your wire on the positive wire side if you are pulling from the main vehicle power bus you need to upgrade the wire from the battery to the main vehicle bus. If you are running a new wire to run your additional hardware you do not need to upgrade the factory wire but there is absolutely no harm in upgrading the factory main wire and if you go up by one gauge (from 6 to 4) you MAY notice your headlights get brighter or your windows roll up and down faster. Upgrading the wire to the Starter is only necessary if it is the same wire that also is responsible for feeding the main power bus. If you do upgrade the starter wire you MAY find the starter works better but you may not notice any difference at all.

        When upgrading the ground wire in these cases you need to upgrade the main ground wire from the battery to the engine block and either upgrade or add more grounding straps.

        Having said all of that realize that larger gauge wires tend to be far less resistive against the power going through it than a smaller wire. This means if you replace a 6 gauge wire with a 4 gauge wire you SHOULD in most cases see the voltage at the equipment end higher. However in reality if the wire is already oversized for the power requirement you shouldn't see a measurable increase. The OEM may have sized the wire to save money and has reduced the size as much as they can where it is on the edge of being too small but not so small as to show up as dim lights or other issues.

        As to Ground Loops. You can do your own google searches but as an example of the information at

        This article talks about ground loops being because of different "potentials". What this means is that similar to how a larger wire is a lower resistance that an equal quality wire of a smaller size this is also the case when looking at ground loops. But since we are talking about automotive we are generally talking about the ground being a panel or a frame member in most cases. Because cars are built using spot welding for most of the cosmetic metal panels they do not form a good ground connection to the main vehicle ground "plane". A piece of metal may also be a different grade of material which may offer a different resistance as well.

        What this means is that if you have ground locations with differing amounts of resistance then the power seen by devices grounded at different locations will see a different ground "potential". What happens in this case is if the battery is providing a solid 12 volts you may have one ground position that when tested shows 11.9 volts to the same power source and another ground location shows 11.99, another 11.85. These different voltages can cause the different pieces of equipment to also see the different voltages which is seen as hum, hiss etc.

        With car audio one of the ways to reduce the hum in your system is to use wires larger than you need for each device, then take them and ground them all to the same point in the vehicle. This includes ANY amplifiers or anything in the sound stream. You can also have other devices such as HID headlights or power inverters that are on a different ground potentials throw off RF that can be picked up by your audio system as well but these generally don't affect noise in most systems. This is one of the reasons why in larger systems you may see power distribution blocks for both power and ground with the power leads going directly to the battery.

        Another way is to increase the size of the wire feeding the ground to the device. By adding more wires as is done in the pictures you list there you are bringing more areas of the vehicle to the same grounding "potential" and is a very valid way of doing things. You could for example run wires to any body panel that is spot welded on and is otherwise a bad ground location and make it a good ground location by doing this. In my Police version Caprice this is exactly what GM does to reduce the ground loops in the vehicle. That car had ground straps connected to all of the fenders from the frame as well as to the tail pipes from the frame, the rear quarter panels and the floor of the trunk. Bad grounding can do more than just cause noise if the potential difference is big enough. The device or system could see a voltage of 5 volts or 50 volts at a bad grounding location. I have personally seen over 20 volts at one ground location and as low as 2 volts on another bad ground location.

        And yes pipes are a misleading example. You can feed a small pipe to a large pipe and then have that feed another small pipe. With chemical feed systems it would not be unreasonable to see a 1" pipe feeding water and a 1" pipe feeding bleach to a 4" pipe that runs for a while then is reduced down to a 1.5" pipe. This would be a mixing chamber because the retention time inside the 4" pipe would be significantly longer allowing proper mixing. There is no equivalence in Electricity.


        • #5
          It only took the right pic in your (Champak's) link to decide STAY AWAY!!!
          That's the short version. The longer version was along the lines of "What a bunch of fwits! To think I thought simpler 'absolute earth/ground' engine grounding implementers were undereducated halfwits. I had enough trouble bolting TWO ground eyelets with a ~19mm diameter bolt to my engine block (eventual contamination caused destruction of my Alpine faceplate's display) and these guys are bolting SEVERAL to a plenum or similar?!! At least my block was heavily connected to my alternator ground - not thru alloy and bolts thru gaskets to blocks to the alternator. To think I complain about people conned into needing voltage sensing battery isolators along with expensive (of course!) dc-dc converters to 'ensure' their remote battery(s) are properly charged... LOL! Some marketing dude has done a real con job with these kits! Oh heck, it isn't a BMW...".

          I would love to hear their justification for all those vibrating and heat prone cables... NO! I wouldn't!

          Re ground loops, they do not involve the engine (alternator) - battery - body bonding. (Even if you only have 2 cables to the engine and body from batt-, you still have a ground "loop" thru engine to body (chassis) paths.)

          Ground loops in DC systems are caused by path differences - ie, interconnected systems not using the same GND point (tho they can be split into power GND and signal or digital GND depending on the system). They will have a loop involved tho it may not be like AC ground loops. (IE - in domestic hi fi systems, ground loops are literal loops. eg from electrical ground/earth to an amp and CD player or TV, then the signal ground between the amp and CD or TV. That's an electrical loop which then picks up AC hum or radio interference etc. AC systems do not suffer from power path voltage drops like DC systems do. Oh, and we can usually ignore distances in vehicle paths compared to the tens or hundreds of meters in some AC supplies (where maximum 'ground resistance' should be specified as an impedance, not resistance) but that's referring to propagation delays - not antenna effects.)

          The above is paraphrasing what redheadedrod said.

          As to any thicker or additional wiring, it is plain old Ohm's Law (V=IR) - the lower the resistance, the lower the voltage drop for a given current. Even adding a 1 Ohm cable in parallel to a 0.000001 Ohm chassis ground lowers the ground resistance.

          Powering direct from the battery is well known here and elsewhere. (However that makes no difference to whether the "thin" alternator to battery cable burns.)

          Most vehicle grounding systems are probably batt- to engine (that's almost universal) and batt- to body (chassis). The GM system Red mentions is far rarer (ie, batt- to chassis is more reliable and cheaper than engine to chassis.)
          But IMO as part of the big 3 (or big 4), whichever is missing can be added to further reduce resistance as well as provide redundancy.

          BTW - the axial (outward) strands of a spiderweb is the ideal grounding system (ie, single ground point). It's the radials that go around the web that cause the problems.
          But fill in the web and you have the perfect solution...

          But yeah, totally disregard whatever tf that Infiniti site is grounding.... (Moronous Infiniti?)
          Last edited by OldSpark; 02-21-2014, 03:12 AM.


          • #6
            Ok, I agree with everything both of you stated. Two things.

            1/ Can you explain this statement a little more?
            Originally posted by OldSpark View Post
            BTW - the axial (outward) strands of a spiderweb is the ideal grounding system (ie, single ground point). It's the radials that go around the web that cause the problems.
            But fill in the web and you have the perfect solution...
            2/ one of the statements I've seen for this spider web of wires is it provides the quickest and cleanest way back to the battery- instead of going through the chassis first and adding resistance which eventually goes to the battery anyway(that is essentially what they are doing, picking up all the grounding on the chassis, and sending them directly to the battery, meeting at a main point to combine them to one wire for the battery-). What's the logical argument against that premise?
            Last edited by Champak; 02-21-2014, 11:57 AM.


            • #7
              O man, I just downloaded those NicoClub pics and had a better look. It's even worse than I thought!
              I hope their vehicle mechanical solutions are better (or do they add AFM resistors and bigger injectors and multi-trode splugs and rehashed mobile-phone chargers to improve performance?).

              Addressing your last questions:

              The spider web. I may have used the wrong terminology (radial, axial etc), but...

              The first ideal part is all (signal) grounds to a common point. You may have seen PCB tracks joining like an * (asterisk or star) to a single point. (I couldn't find any pics. Besides, I have great difficulty posting them in mp3car.)
              That is to avoid ground loops tho only applies to signal grounds as opposed to digital and power grounds.

              It's when that star or asterisk has cross connects like the concentrics around the web star that you have problems - ie, ground loops.

              The perfect solution fill was meant to convey a ground plane or solid filled-in spider web - ie, a sheet of conductor or a chassis/body of 0-gauge thick copper or steel etc. But ignore that - on a car scale you get issues like Eddy or circulating currents - aside from the fact it is not practical to add...

              Keeping in mind that DC 'ground loops' can involve series resistance voltage drops as described by redheadedrod & wiki etc.
              And if people use the argument that steel conducts less than copper but do not take into the total path cross-section (ie, hence usually a lower overall resistance), oh well...

              Originally posted by Champak View Post
              one of the statements I've seen for this spider web of wires is it provides the quickest and cleanest way back to the battery- instead of going through the chassis first and adding resistance which eventually goes to the battery anyway(that is essentially what they are doing, picking up all the grounding on the chassis, and sending them directly to the battery, meeting at a main point to combine them to one wire for the battery-). What's the logical argument against that premise?
              The logical argument for their premise is that they have measured the chassis resistance and engine block and bolt resistances and found that copper cables have less resistance from those points. They should be able to show you their results - and compare with a single short fat cable from batt- to chassis or to the engine block or similar.
              Perhaps too that their cable paths back to the battery have less inductance than the chassis (and maybe therefore the propagation delay is also less?).
              And their spider web does not act like an antenna.

              Not that the above is exhaustive, and readers might think that I'm taking the mickey out of them, but I have heard that some chassis are poor conductors. Admittedly that's been in rusted out VWs etc, plastic and fibrerglass vehicles, and vehicles whose metal chassis are glued and not bolted or welded together.
              Redheadedrod and others claim insufficient spot welding, but I don't recall such on a chassis; body panels yes, but even that seems rare (and who'd put BIG grounds on (thin) sheet metal?).
              However isolating each ground and measuring the voltage drop at a given or required Amperage indicates original or improved ground quality. That should be very easy to show - just like all the Stiffening Cap oscilloscope pics that show the resulting improvement for long burps and peak SPLs.
              Oh dear, I seem to be in a somewhat mocking mood!

              It was response to a thread about a bad day of car audio installation that I viewed those Infiniti/NicoClub pics. It was then I saw the daisy-chained ground straps, etc. (I posted a pic extract and mentioned mp3car.)
              Even without experience or knowledge it should be pretty easy to see some major issues... like one bolt holding several cables/eyelets; the ground path involving multiple transitions between differing metals, etc.
              Older or experience readers might recall how oxygen-free cable lacked the "molecular domains" (crystals?) that distorted audio quality (yes, for the power feed as well as speaker cables). I wonder what copper - eyelet - eyelet - copper or copper - eyelet - alloy would do? And that's not mentioning the surfaces and their oxidisation and tension and gaps etc.
              But even without the knowledge of that old bullsh it should be easy to see how those junctions can get contaminated. (As I wrote, I blew my Alpine display despite a big and very torqued bolt attaching 2 big clean eyelets to the engine block!)
              Then the bolts... They will not expand or vibrate loose or electrolise? And they won't vaporise given a hefty current or fault?
              And of course they can lose any one of those bolts because they have alternate paths (redundancy) - even that bolt with 4 cables?

              I wonder what their battery -ve ground looks like since it is the battery that supplies the real heavy currents? (And often step-increase shortfalls for slower reacting alternators.)

              And again, I'm sure they can provide some evidence of how effective all that has been, and at what price, and compared to the normal ways we would do it.

              You should find that I've been consistent in many of my thread replies - even this thread - where I have paraphrased these same basics or issues repeatedly. The only thing missing from this one is re speed - ie, electricity traveling quicker thru less resistance or copper (LOL!) - though I preemted that re propagation delays (eg house AC grounding versus vehicular DC grounding). (Maybe they avoid that since their cables ground paths are longer than the OEM paths?)

              If someone knowledgeable like Mickz can counter or moderate my views I'd certainly welcome it.
              But as it stands, those Infiniti pics are one of the most pathetic and stupid things I have ever seen implemented. I reckon it beats the fuse that someone inserted into their alternator-to-battery +12V wire which was far more hazardous than no fuse! (Tho that still stands as an example how or when NOT to fuse.)

              I hope I have been clear enough despite this reply length.
              I can go far deeper, but I prefer to stick to one situation until that is understood before adding in different scenarios etc - ie, one bit or issue at a time. (You might think I have diverged, but looking at it from my POV...)

              Actually different scenarios can result in completely different solutions. But until the basis are understood... Hence why we start of simple, then add, then explain why the difference. (I note that's something often missed in discussions. Even tertiary education often misses that.)



              • #8
                In case I haven't been clear enough, FORGET everything in NICOclub's NEED HELP WITH A GROUNDING KIT.

                Apart from having others agree with me (via the grapevine), it is simply crap.

                That was all I wanted to say, but since I had a quick peruse of grounding kits & info on the above site (noting their naysayers and those that point out the difference between normal power grounding for audio etc)...
                IE - here comes my ramble....

                Cases where it does help mean either a degradation or loss of OEM grounds, or a crap OEM design.

                Better grounding of sensors? You mean such sensors do not have their own ground or shield? Bad Design!

                Better grounding of EMS? WTF? How the heck does that improve things? The CPU has its own regulated supply (eg 3.3V, 5V etc) which is unaffected by grounding (assuming there is a GND of course!) and any heavy switching (eg, GND switching of injectors, IgCoils) should not be to that regulated GND.
                Sure, an intermittent or varying GND may effect things, but upgrading EMS grounds should not change things noticeably. As if manufacturers would skimp a few cents on a GND which effects performance and fuel economy! (Design faults excepted.)

                It's as bad as those $80 'power smoothers' that plug into your cig socket that give the EMS etc much smoother DC and hence (sic!) better performance. Now that should have obvious flaws anyhow (EMS's filters & regulators; where the cig socket resides electrically) but those of us in the know know that they are nothing more than a mobile phone charger but without the output lead and a LED instead.
                So how many of you get better acceleration when cig charges are plugged in?.
                Of course that doesn't stop these incredible testimonials, but I suggest that even the non-bogus ones are suffering the placebo effect, or need to justify their wasted expense.

                But now I think I should do the same as my learned friends - it wasn't worth their while posting comments.
                Last edited by OldSpark; 02-22-2014, 09:46 PM.


                • #9
                  No worries, I'm all the way on your thinking. It didn't make much sense to me. I was actually suppose to do the big 3 for the past six months but haven't gotten around to it, then I came across that bird nest of wires and said wtf. Just wanted consigning from someone on that bird nest who knows more than me on this stuff, and more insight on the big 3.