Re: GROUND WIRE QUESTION....................
[Re: Adobedude]
#1372362
01/20/13 02:38 PM
01/20/13 02:38 PM
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Joined: Jan 2003
Posts: 32,394
Quicktree
I Win
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I Win
Joined: Jan 2003
Posts: 32,394
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Quote:
Using the frame as a ground (to bare metal) I had issues with starting, charging, fuel pressure...I could lower my fuel pressure by simply turning on the fan. I ran all my grounds back to the battery, problem solved. Granted I have an extra 6' length of welding cable but at least it runs now. And as said, the PCM throws a fit if doesn't get enough power.
seen that more than once
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Re: GROUND WIRE QUESTION....................
[Re: Quicktree]
#1372363
01/20/13 04:28 PM
01/20/13 04:28 PM
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Joined: Nov 2003
Posts: 440 SW pa
goldenlancer
mopar
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mopar
Joined: Nov 2003
Posts: 440
SW pa
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my spark plugs were burning black leaned out to a point to where it wouldn't run right then bumped my head and said it needed grounded from the batteries to the motor lots of problems fixed all at one time charging, ing. and fuel ran a #1/0 wire to the motor and grounded everything off the motor . i thought I had a good ground when I welded a bolt to the cage which is grounded to the body and sub frame The aluminum front motor mount to the motor (I thought would be enough (not) lessons learned
N/SS
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Re: GROUND WIRE QUESTION....................
[Re: dvw]
#1372365
01/20/13 10:14 PM
01/20/13 10:14 PM
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Joined: Nov 2004
Posts: 4,330 Lynchburg, VA
Leon441
master
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master
Joined: Nov 2004
Posts: 4,330
Lynchburg, VA
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I am hearing a lot of rules about electricity that are misused. Sounds like a few to many conversations at the bar.
It doesn't matter which way the current flow is. Cut your + or - cable and insert an ampmeter. The current is the same anywhere in that series circuit. So yes running a 2 gauge + with a 4 gauge - leaves you with a 4 gauge circuit.
We run very low voltage high current stuff at work. If I told you some simple rail circuits and how they worked you would say no way. I'm telling you WAY.
A mild steel car with good welds will carry electricity just fine as long as the connections are good. But, usually they are not. Flat washers don't penectrate and make a good connection. I cut and fix old junk all the time. There are a lot of welds that will not carry electricity well. Don't know how the car stayed together either. CHROME MOLY has trouble carrying electricity. It has carbon in it just like resisters.
My recommendation is run a #4 welding cable from the battery to the engine. Then go from that to a bulkhead. From bulkhead to the body and chassis in as many ways as possible. Use grounding washers otherwise you are pissing in the wind. I have a grounding lug on my chrome moly cage. It is just a conveneint connection point.
If you have concerns about how well a peice of tubing or any steel can carry electricity use an ohm meter and check it. For a better test. Take a 55watt headlight and run copper wires to it from your battery fully charged. Take a current reading. Then unhook the negative wire and hook to your chassis. Take another current reading. If the current is the same and the battery voltage was the same. Guess what, your car is fully capable of carrying electricity.
If you want to run big ground cables and ground busses with plenty of bonding wires it will not hurt a thing. Grounds are good. Better to be well grounded than not. There are many cars with limited grounds that do just fine. The more electronics you have the more you need good grounds.
Leon 22 years of Signal Maintaining and Signal Electronic Specialist Norfolk Southern Corp.
Career best 8.02 @ 169 at 3050# and 10" tires small block power.
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Re: GROUND WIRE QUESTION....................
[Re: Cab_Burge]
#1372367
01/20/13 11:31 PM
01/20/13 11:31 PM
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Joined: May 2008
Posts: 1,131 Thigh-Gap Junction
@#$%&*!
New user name, Same old jerk!
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New user name, Same old jerk!
Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
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But Cab, you never stated whether the battery was charging or discharging or whether you wanted Electron Flow or Conventional Current, which are both equally valid. Add me to the list who use the floor pan as a ground circuit, and it's the biggest conductor in the car. Now, I'm NOT depending on the factory spot welds but have 2x3 frame connectors welded fully and then some. If your engine cranks over fine and you're having ground issues they're NOT in the crank circuit. It's best to keep every wire as short as possible and running miles of ground wires goes against that. Every device on my car is grounded as close as possible. Keep in mind that the big cables are only necessary to crank the engine over. Once the engine is running the charging system supplies the power to run your equipment AND charge the battery. No charging system? Have fun in the bleachers while the rest of us race for the money. My positive cable I took out of another car 25 years ago and I'm pretty sure it has 7 strands. It's very stiff and probably half the weight of the typical welding cable used. Before anyone tells me it won't work I have years of time slips to show for it. Add one ground cable from the torsion bar crossmember to the starter stud and all is well. Quote:
MrP, my point is that most people ASSUME current flows from the positive post to the negative post, which of course it doesn't! :...
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Re: GROUND WIRE QUESTION....................
[Re: dvw]
#1372371
01/21/13 11:48 PM
01/21/13 11:48 PM
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Joined: Jan 2003
Posts: 2,813 Blue Ridge, VA
Plumb Wired
master
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master
Joined: Jan 2003
Posts: 2,813
Blue Ridge, VA
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I am a Spaghetti Menders dealer/installer and I firmly believe in Bob Lapp's "floating ground" system. Does it add some weight? yes, but I will take the piece of mind of a properly operating electrical system vs. a few pounds.
Here is some info from the Spaghetti Menders website, please excuse the way it is written. He tried to use some humor by using his dog Noodles as the author.
"Hi my name is Noodles I'm the inventors helper - I do all the leg work. My job this week is to let you know that all the electricity used in your car needs wires to get from the battery to all the devices you operate.
But the wires are just one of many things that need to be rated for the devise you will be operating. You will have a switch for turn on and off the devise. A fuse is for protecting the wire from damaging your car if the load is higher then the switch or wire can handle. Some times a relay is used if the load is higher then the fuse or switch can operate.
So now that you are confused I can shed some fleas on the problem, The biggest thing I see is that the ground is not installed right, yes the ground wire that hooks to the car frame. When cars where first made in the 1920 they used the car body as ground to save money on wire and half the labor to install (1 wire) for each device, Now it's 2005 and you wired your race car that way and your fuel pump and fans don't work right and you keep burning up switches and blowing fuses and you can't find any shorted wires but it keeps on doing it and you lose the race.
Back to the wires when power from the battery go's to the switch then to the device you turn on ( fuel pump - fan etc. ) it has to get back to the battery ground to make it work, but if you put anything in the path that is not able to handle the load before or after it you can make the fuse blow. Yes I barked at you about bad grounds can blow a fuses. All the power needed to operate your fuel pump and fan has to start at the battery and end at the battery so anything that slows down the power will give you an itch you can't scratch. So the best way not to have problems is to make sure you have the shortest path from battery to the fuel pump and back to the battery that's where relays come in they are remote switches it's by your pump and needs a small amount current (the power that makes things work) to operate and can switch high current like fuel pumps and fans.
So now we have the shortest route from battery to fuse to relay to pump back to battery with wire sized for the current draw of your pump. The best way to size your wire is to go one size bigger than they supplied under 6 feet,Two sizes bigger over 6 feet. The fuse is there to keep high current draw like a shorted wire that rubbed through on sharp piece metal or your pump that shorted out from heat. That's the only need for a fuse to stop the fire when the wire gets to hot from to much current. Now the switch that's mounted by the dash only has to power the relay at 1/4 of a amp draw less then a small light bulb that means very small wires and switches can operate fuel pumps and fans.
Now back to grounds if the power goes through a wire to your pump it has to go through the ground wire to the battery not the car frame, rust that you can't see and steel is not as good a wire as copper. Now this wags my tale, if you have copper wire on your fuel pumps power supply and you hook the ground to the frame what ever is lost in going through steel is felt in the pump because it's like a hose if you stand on one end, the water only flows the amount that get by your foot. So no matter where you put your foot the flow slows down. It's the same with wiring your car, if you slow it down by using steel as your ground, it makes it harder to operate and can blow the fuse and not having a shorted wire, you can slow down your pump making it work hotter and then burn up."
Last edited by Plumb Wired; 01/21/13 11:52 PM.
RIP Monte Smith
aka: OutlawFish '98 Bickel Dodge Dakota PST
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Re: GROUND WIRE QUESTION....................
[Re: Plumb Wired]
#1372372
01/22/13 01:22 PM
01/22/13 01:22 PM
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Joined: May 2008
Posts: 1,131 Thigh-Gap Junction
@#$%&*!
New user name, Same old jerk!
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New user name, Same old jerk!
Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
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Quote:
Here is some info from the Spaghetti Menders website, please excuse the way it is written. He tried to use some humor by using his dog Noodles as the author.
I read through that and am unimpressed as he's written some of the same faulty logic that can be found in this very thread. All current passes through the battery ONLY if you have no charging system. The car chassis can be a good conductor without being made of copper simply because it has an extremely large area compared to ANY wires in the car.
Keep in mind that cars have been designed using chassis grounds forever. The only exceptions that I can think of are computer sensors that have a ground wire back to the computer. This is necessary because the computer is modulating engine timing and fuel mixtures based on subtle (very small) voltage changes from the sensors. You can't do this if the sensor readings change every time you turn on the blower, headlights, brake lights, etc.
CW
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Re: GROUND WIRE QUESTION....................
[Re: @#$%&*!]
#1372373
01/22/13 03:53 PM
01/22/13 03:53 PM
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Joined: Aug 2003
Posts: 43,230 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,230
Bend,OR USA
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Speaking of computers, let me throw in the term "Peremeter ground" Anybody know what that means?
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: GROUND WIRE QUESTION....................
[Re: Cab_Burge]
#1372374
01/22/13 09:28 PM
01/22/13 09:28 PM
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Joined: Nov 2003
Posts: 7,348 Mt.Vernon ,Ohio
VernMotor
master
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master
Joined: Nov 2003
Posts: 7,348
Mt.Vernon ,Ohio
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Quote:
Speaking of computers, let me throw in the term "Peremeter ground" Anybody know what that means?
Ok I bite what is that ?
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Re: GROUND WIRE QUESTION....................
[Re: Cab_Burge]
#1372376
01/22/13 10:01 PM
01/22/13 10:01 PM
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Joined: Nov 2004
Posts: 4,330 Lynchburg, VA
Leon441
master
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master
Joined: Nov 2004
Posts: 4,330
Lynchburg, VA
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Isn't that Perimeter Ground? Used to prevent static and surge damage.
Spegetti Menders must not understand E equals I times R. I am sure that is not the case but when reading this that is the conclusion most EE's would come up with.
A high resistance circuit does not blow fuses. It actually limits current. Take 10 volts to make the math easy. 10 divided by 10 ohms (9 ohms load or appliance plus 1 ohm for your copper feed and ground) That is 1 Amp. Now take 20 ohms. (9 ohms load or appliance and .5 ohms for your copper feed wire and 10.5 ohms in your old Mopar chassis) That's 1/2 Amp.
Spagetti menders knows copper grounds are better they just don't seem to state why correctly for every type of load or appliance. A bad ground does not blow switches and fuses necessarily. A light bulb will only light based on the voltage at the light bulb. An electric motor or anything with inductance on the other hand will act much differently. MIke brought up spagetti menders and they do have some really nice stuff but all auto electronic providers recommend good grounds for the same reason. I hope not to bore you guys to death with what follows that should help explain.
Without getting into mho or J factors and get everyone including myslef thoroughly confused a good ground is never a bad thing. If everything is done correctly a chassis ground works. Star washers, clean welds, and good steel. Sorry anyone who has ever tig welded on Mopars knows the metal is a little funky. So if you run good ground wires from engine to battery you are not wasting any weight or money. And to all your equipment especially including relays and the MSD.
Why would a bad ground burn up switches, fuses, and appliances? A bad ground is never just a bad ground. It comes and goes. So back to resistance in the circuit. When it comes and goes so does the current flow. Well some appliances are very demanding like a spinning fan. Start making and breaking the circuit like a bad kid with your light switch in your home and something is going to give. Your home has at least a 15 AMP breaker so the switch and bulb is usually first to go. On a car the trouble is much harder to find.
Industry leaders are just trying to save you a lot of trouble and recomend running grounds to elliminate these failed circuit possibilities and phone calls trying to find bad circuits in your car.
Race car wiring has come a long way. I know service trucks use the frame for a ground and there is always something malfunctioning and it is 90% of the time ground related. So I am not going to criticize anyone for running grounds on a race car. Just their reasoning. LOL
Leon
Career best 8.02 @ 169 at 3050# and 10" tires small block power.
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