How to PROPERLY/COMPLETELY ground your electronics

[PoorManQ45]

Ok guys. I've read enough of this grounding crap. Taking a wire from whatever you want to ground and attaching it to the frame(Bare metal) is not a real ground.

To completely ground your system, you should hook up a ground wire from the part and connect it to the negative terminal on the battery. This will give you a complete/Proper ground.

It is a common mis-conception that the ground and negative wires are different. This is not true. They are one and the same.

If you have any disputes and or questions, feel free to ask.

BTW, the ground and negative on a 110~130V house lead to the same place. It is just because of the Electrical Code that these two wires are kept separate until they reach the breaker/fuse box.

[PoorManQ45]

What I like to do is to run a 12 AWG Romex 3 wire cable into the trunk. The three wires hook up to:Black =Positive battery terminalWhite = Negative terminalGround = Negative terminal

For those of you who don't know what a "Romex" cable is, I'll tell you. It contains three solid wires (Black, White, and bare). The Black and White wires each are seperately insulated. The bare(ground) wire has a construction type paper insulation. All three of these wires are then contained within another insulator.

These wires are rated up to 20amps @ 120v. This means that they are capable of handling ~200amps at 12v (120v/12v = 10. 10 x 20a = 200a). 200amps is ~2400w (200 x 12 = 2400). This should be plenty of power for any system, but if you need more, you can use the "ground" wire as another positve/hot wire. This will effectively double the cables power handling capability.

[slipnfall]

I know this is an old post, but it's good to bring these important points back every once and a while. Just to back PoorMan up on this:

A chassis ground will indeed make it's way back to the battery, but you are fighting against welded joints, corrosion, etc. It is best to have a directly link for *each* ground connection back to the battery. Obviously this isn't always feasible, but none-the-less ideal. The chassis ground is in many was intended for safety purposes. For example if a high-voltage spark plug wire should hit bare metal, it will return to the battery, and not leave the body at a high potential.

You should avoid 'dasiy-chaining' ground or power wires because you will develope impedance(essentially resistance) differences between each point. In other words, don't tap off the keyed ignition power to your stereo, then go from the stereo to neons, then from neons to whatever. Run an individual wire for each device from the source point.

Also when you simply ground to the nearest chassis point, you are introducing ground loops. Basically the return currents will 'loop'/travel to lower resistance paths untill it finally reaches the lowest potential-the battery (-) terminal. This looped path can be longer than the ideal shortest path. In audio applications, ground loops are a HUGE contribution to noise problems.

I realize this probably didn't help to clear things up, but some people like an explaination.

Cheers!-Slip

[Silvia2b]

Also it is a good idea to mention if you are running heavy gauge wire though for the power, you need to upgrade the same size cable for the negative terminal of the Battery. in addition to the existing grounds on the battery. I KNOW THIS IS KINDA LONG SO... HERE GOES.For instance; you are adding an amp. You have a 4 gauge amp kit that has 17' feet of power, a glass style AGU fuse holder, some ring terminals, and 3.5 feet of ground. Here is how I would recommend you connect you amp for the best performance.1. Disconnect the negative terminal of the battery. Cut 10-12 inches of the power, then strip both ends, connect one end to the fuse holder, but don't put a fuse in it yet. Put a ring terminal of the proper size on the other stripped end. This will connect to the + Battery terminal in a later step.

2. Run the remaining wire through the car, starting from the engine compartment, to your chosen amplifier location. Connect the positive terminal of the amp to this wire which is not connected to anything at the other end in the engine compartment.

3. Find a location in close proximity to the amp for a suitable ground. Less than 2 feet is ideal. Save the remaining length of ground for the engine compartment. Then clean the area for you grounding screw or bolt, I mean remove the paint & primer in like 3/4 inch square around this point. I would use a bolt and a lock-washer and nut to secure it if you can access both sides of the area where the ground will connect to the vehicles chassis. Warning! BEFORE DRILLING ANY HOLES BE SURE YOU WILL NOT HIT ANY WIRING HARNESSES OR FLUID LINES. SUCH AS BRAKE LINES OR HYDRALIC FLUIDS. Check underneath the car in this area you will be drilling as well, if you are mounting the ground to an exterior panel, to be sure of no obstructions or vehicle components that will interfere with your ground bolt or the drill bit as you drill the hole. Connect the one end of the ground wire to the negative terminal of the amplifier. Strip the other end of the wire and crimp on a ring terminal to the ground wire. Bolt the terminal to the spot you cleaned up and drilled with your bolt.

4. Run your remote turn on wire and RCA's to your head unit and keep the RCA separated from your power wire if possible. Connect these after all electrical connections are complete at the amp. for example ( Speaker wires, remote turn-on, Power, and Ground)

5. Connect the short length of remaining ground (hopefully 10-12 inches) to the Negative battery terminal. Then bolt it to the chassis where you see other ground wires. Make sure this is also free of paint.

6. You should now have all connections at the amp complete, and the amp mounted. Connect the RCA’s and Remote wire where you ran them to your Head unit.

7. Connect the remaining end of the power wire to the other end of the fuse holder. and insert your fuse.

Last step8. Reconnect the negative terminal & and start the car. Turn on the headunit, adjust amplifier gains and head unit settings and verfy correct operation of all components. Make sure everything that was losened has been re-tighten before operating the vehicle.

ENJOY! Questions anyone?

[slipnfall]

: I skimmed over it, but looks like good info. It is *so* very important to clean the area you are using as a body ground. The washers with the 'teeth' on them are best for this, rather than a traditional flat or lock washer. Some di-electric grease will help keep it from corroding(easily occurs at points of differing metals), AFTER you've tightened it completely.

I'm you-know-what-retentive when it comes to wiring, so I use shielded, multi-conductor cable for my speaker wires. Makes for a cleaner install also.

Anyways, if you have a shielded cable, only ground ONE end of the cable's shield. Trim/insulate the other end. Ground at the end of the cable which is near the audio *source*. ::edit:: My point was that if you ground both ends of a shield, you introduce a ground loop, mentioned above. ::edit::

[audtatious]

I use a wire that hangs out my trunk and drags the ground. Works great.

[slipnfall]

Just a wire? Pfft.. I drag chains...

[audtatious]

Yeah, but my wire is 6" in circumference.

[PoorManQ45]

I use a wire that hangs out my trunk and drags the ground. Works great.

I know you're being sarcastic, but some people might think you're being serious.

For those of you that don't really understand how the car's electrical system works, you MUST ground your equipment to the negative battery terminal. Either directly, or via a chassis ground. Connecting a wire from the positive terminal and running it into the earth does not give you a ground . For current to flow in a battery DC circuit, there must be both a line coming from the battery(positive), and a line returning to the battery(negative) for any current to flow.

I know it should be unnecessary to say this, but I have seen a few idiots try to use an earth ground

[Atomic-S14]

nice write up hehe i should re-do my setup

[91M30]

What I like to do is to run a 12 AWG Romex 3 wire cable into the trunk. The three wires hook up to:Black =Positive battery terminalWhite = Negative terminalGround = Negative terminal

For those of you who don't know what a "Romex" cable is, I'll tell you. It contains three solid wires (Black, White, and bare). The Black and White wires each are seperately insulated. The bare(ground) wire has a construction type paper insulation. All three of these wires are then contained within another insulator.

These wires are rated up to 20amps @ 120v. This means that they are capable of handling ~200amps at 12v (120v/12v = 10. 10 x 20a = 200a). 200amps is ~2400w (200 x 12 = 2400).

This is not a correct analysis. Current carrying capacity does NOT go up as voltage goes down. 12 AWG wires are NOT adequate for carrying 200 amps. Depending on application and insulation, 12 AWG wires are rated to handle only up to about 50 amps. Go to http://www.powerstream.com/Wire_Size.htm or http://www.alphawire.com/pages...art=0 or http://www.vaplastics.com/elec....html for more information.

[PoorManQ45]

You're correct. I goofed big time on that one. Current capacity is NOT dependent on voltage. This is why power lines run at ~14k volts(at the street level). As voltage increases current decreases, but power(watts) remains the same.

This is why I was thinking about installing an 16~18volt alternator in my Q. It'd allow more power to be carried over the same size wires.

Sorry for the misleading remark I made. Thanks for correcting me though

[slipnfall]

This is why power lines run at ~14k volts(at the street level). As voltage increases current decreases, but power(watts) remains the same.

Those voltages are typically only found from between transfer stations, not street level. Also if resistance remains the same, and increase in voltage will cause an increase in current. Remember ohms law: V=I*R.

This is why I was thinking about installing an 16~18volt alternator in my Q. It'd allow more power to be carried over the same size wires.

. You won't increase your current-carrying capacity simply by increasing the voltage. This capacity depends on the type(copper/aluminum), cross-sectional area, and length of your system wiring. Because most modern car electronics expect anywhere from 12-18V constant, it's doubfull that any will utilize any overhead. More likely they will simply regulate down to a fixed known voltage(be it 12V, 5V, whatever). In which case you're simply generating more heat=wasted energy.

Hope that made sense, sorry, it's late(err, early).-Slip

Sorry for the misleading remark I made. Thanks for correcting me though[/QUOTE]
Modified by slipnfall at 1:44 AM 6/1/2005

[Silvia2b]

And I thought this thread was dead and stored in history somewhere.

[PoorManQ45]

Those voltages are typically only found from between transfer stations, not street level. Also if resistance remains the same, and increase in voltage will cause an increase in current. Remember ohms law: V=I*R.

Now that's where you're incorrect.

Increasing the voltage will cause the power(watts to remain the same, well there will be a slight lose in the transformer), but the amperage will DECREASE.

120w @ 120v = 1amp. 120w @ 240v = 0.5amps. As long as the shielding can handle it, any wire can handle any amount of watts as long as the voltage is high enough to be below the maximum ampere capacity. IE, 12awg = NEC rated 20amps. 20amps means nothing without a voltage. mulitple 20 times what ever the voltage is and you can carry that many watts.

So, as voltage increases current Decreases.

You may have been thinking about power(watts), in that case you would be correct as it stays the same.

By street level I meant before the last transformer before entering the house.

. You won't increase your current-carrying capacity simply by increasing the voltage. This capacity depends on the type(copper/aluminum), cross-sectional area, and length of your system wiring. Because most modern car electronics expect anywhere from 12-18V constant, it's doubfull that any will utilize any overhead. More likely they will simply regulate down to a fixed known voltage(be it 12V, 5V, whatever). In which case you're simply generating more heat=wasted energy.

Partially, but refer to above. Power capacity IS dependent on voltage. 120amps @ 18volts = 2160watts is > then 120amps @ 14.4 volts = 1728watts

[slipnfall]

120w @ 120v = 1amp. 120w @ 240v = 0.5amps.

That by itself is correct. However your statement "So, as voltage increases current Decreases.", isn't: so if I put 120V across a 10ohm resistor, your saying that the current will be *less* than if I had 12V across it?? Don't think so...

Increasing the voltage will cause the power(watts to remain the same, well there will be a slight lose in the transformer), but the amperage will DECREASE.

That's the problem, the watts will not remain the same: remember you're changing the voltage, which increases the power. The only way this would be true would be if you were to change the resistance at the same time, which you are not.

I must admit I have never really researched upgrading an alternator: I just always assumed it was able to supply a larger current(thus why a typical alternator is rated at say, 90A).

Respectfully,-Jamie

[PoorManQ45]

That by itself is correct. However your statement "So, as voltage increases current Decreases.", isn't: so if I put 120V across a 10ohm resistor, your saying that the current will be *less* than if I had 12V across it?? Don't think so...

Then what is the point of running such high voltages across the country? Note that they "only" use ~1/0 or 2/0 which are rated for 150 and 175amps, respectively. The way they do this is by running at higher voltages, which allows the wire to carry more watts(power) sinse it requires more watts to equal 1 amp.

Example. 2100000w / 14000v = 150amps. 2100000w / 210v = 10000 amps.

Can you see what I'm getting at here? As the voltage increases the current, for a given amount of power, decreases. Thus why higher voltages are used over long distances, and over such small wire.

That's the problem, the watts will not remain the same: remember you're changing the voltage, which increases the power. The only way this would be true would be if you were to change the resistance at the same time, which you are not.

In this case we are talking about pure wire with almost no resistance.

I must admit I have never really researched upgrading an alternator: I just always assumed it was able to supply a larger current(thus why a typical alternator is rated at say, 90A).

Respectfully,-Jamie

Yeah, most people are fine with the factory altermator. It usually has ~15% headroom.

[slipnfall]

Ok, I think I'm finally catching up with you here. When you said that current decreases with an increase of voltage, I was not factoring in a constant power. My bad. So yeah, I gotcha. I think we were simply revolving around the same truths/principals.

BTW are the Qs' alternator really rated at 120A?

[slipnfall]

You can thank me for that. Just had to add my 0.02...

[PoorManQ45]

BTW are the Qs' alternator really rated at 120A?

Yeah, I think so. IIRC, I installed a Bosch 140a unit. I'm thinking of adding another 120amp alternator just for the hell of it.

Do you, or anyone else, know if there would be any problems with doing this? I mean, The alternators would be putting out more then double that of stock. Would there be any damage to the battery from over charging?

Good Discussion BTW.

Ok, I think I'm finally catching up with you here. When you said that current decreases with an increase of voltage, I was not factoring in a constant power. My bad. So yeah, I gotcha. I think we were simply revolving around the same truths/principals.

Yeah, we were both correct. You were correct in saying that if the resistance(10ohms) stays the same the the current increases as voltage goes up.

[slipnfall]

Umm, not sure. Depends on what you want that extra power for. If it's audio, airbags, etc, you can add a second alternator for *just* those items. Take the strain off the main supply for ECM and stock powered devices. Another way to add a second is to buy two identically-rated alternators and wire them in parallel. This way you wouldn't have to worry with the excessive voltage. I don't think you'd have to worry with an exploding battery or anything at 18V, but I would certainly buy a high quality one(Optima, or other), and request the maximum charge ratings.

[PoorManQ45]

YEah, I know to wire them in parallel. Don't want th evoltages adding up

I might have to invest in a sealed battery sinse I'm moving mine to th etrunk.

[slipnfall]

Well what I meant was you wouldn't have to worry about excessive voltage, from a single higher-voltage alternator. It shouldn't affect the charging rate AFAIK: there is no 'current' limit in an alternator specifically for charging only. Paralleling them would just provide more if needed.

[left channel audio]

i must have missed where someone said they are putting a higher voltage alt. in their car..... replacing your factory alt. with one that is cappable of 140amps is no problem at all. Are you going to increase the voltage out of the alt.???????? no.. still the same voltage just at a higher current.

[Simmsled]

Wow. This thread is outta control. I'll be back at home on the 13th of June and i'll leave one of my crazy long posts. cool.

[audtatious]

Wow. This thread is outta control. I'll be back at home on the 13th of June and i'll leave one of my crazy long posts. cool.

Is that a threat?