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JRouche
01-19-2010, 12:45 AM
So.. I have this grounding stud on my car. It connects the ground from the battery to the frame. Its a 1/2" threaded rod. The cable has a 1/2" lug on it. What I have is a large steel washer at the bottom of the stack (against the frame), then a copper washer, then the cable lug, a copper washer on top of that then a copper lock washer then a copper nut.

I was thinking about putting some electrically conductive paste on the threads of the stud to help with conductivity. It may not be needed but its just something to do. I have 5lbs of this copper powder and cant find a use for it LOL

I have 5lbs of pretty fine copper powder. Im thinking its about 325 mesh, I have to find the paperwork. Its a high density air atomized powder.

Anyway. Im thinking of mixing up a very small amount with a grease or other carrier to make a paste and wipe it on the post prior to assembly.

Any ideas on the carrier?? I have a pretty good assortment of greases. Even thought about petroleum jelly. Or even a silicon based sealant. Or heavy gear oil that will flow off and leave the copper particles.

Im looking for opinions. Yup, open for opinions. That means any suggestions or comments are welcome. Any and all are welcome... JR

Carld
01-19-2010, 12:53 AM
Perhaps you could mix it with silicone grease or buy a tube of dielectric grease. I haven't thought about mixing copper powder with anything for better contact.

The petroleum jelly may work. Can you run a resistance reading before and after to see if it helps?

Highpower
01-19-2010, 01:14 AM
Mix it in a bottle of model paint and slather it on. :D

http://www.permatex.com/documents/tds/Automotive/15067.pdf

http://www.testors.com/category/136648/Acrylic_Paints

SpyGuy
01-19-2010, 01:26 AM
So.. I have this grounding stud on my car. It connects the ground from the battery to the frame. Its a 1/2" threaded rod. The cable has a 1/2" lug on it. What I have is a large steel washer at the bottom of the stack (against the frame), then a copper washer, then the cable lug, a copper washer on top of that then a copper lock washer then a copper nut.

I was thinking about putting some electrically conductive paste on the threads of the stud to help with conductivity. It may not be needed but its just something to do. I have 5lbs of this copper powder and cant find a use for it LOL

There's a product on the market that is a copper-based paste for exactly what you are describing. I have a small tin of it. It was pricey. I think it's made by Wurth, but I can't say for sure.

If I were going to "brew my own", I would not use dielectric paste... that would be going in opposite directions. :eek: Instead I would mix your copper powder with anti-seize. Should work well both for conductivity and for corrosion protection.

Btw, I would not use the steel washer on the bottom. I would use a wire wheel to get the frame bright at the bottom of the stud, wipe on a very thin layer of conductive paste and then place the copper washer right against the frame. Then the cable lug, then a copper washer, then a steel washer, then a steel lock washer, then a steel nut. The copper washers are for both conductivity and deformation. The steel washer protects the copper washer from the steel lock washer. The steel lock washer and steel nut will be more secure than a copper lock washer, and the steel nut will be less likely to round off while tightening.

Btw, if you're looking to dispose of some of that copper powder, I'll take some off your hands. :cool:

Willy
01-19-2010, 01:44 AM
Personally I doubt it will make a bit of difference whether you use the copper paste or not.
I think you may be better off using several grounds, (engine, chassis, body, etc.) and sealing these grounds with a good coat of paint or a moisture proof sealer to prevent loss of conductivity through corrosion. I have installed several such additional grounds on one of my vehicles and after seven years I cannot measure any additional resistance or voltage drop with my Fluke multi-meter.
But if you're bent on using it, it's not going to hurt.
I'm sure there must be other worthy applications for the copper powder but at the moment I can't think of any.

darryl
01-19-2010, 02:03 AM
Your best point of conduction is going to be between the lug and the frame, with nearly as much coming from the other side of the lug and through the stud. Leave out the steel washer. I would probably use shoo goo (aka goop) to mix the copper in with, using a high percentage of copper powder, then coat everything and assemble it. Work quickly once you squeeze out the shoo goo, and wipe away all that you can from the join area when it's put together. Every bit that you're able to wipe away is unable to contribute to the conductivity, so once that's done, leave it to cure. Once it's cured, tighten more if it allows, then apply some paint.

dockrat
01-19-2010, 02:18 AM
If I were going to "brew my own", I would not use dielectric paste... that would be going in opposite directions. :eek: Instead I would mix your copper powder with anti-seize. Should work well both for conductivity and for corrosion protection.

I agree with SpyGuy. Mix it with anti-seize compound. I have a couple of cans of that stuff here( Kopr-Shield ) and it says on the can "Conductive anti-seize compound for the electrical industry"

It looks and spreads just like any other anti-seize compound I have used but is loaded with copper

jatt
01-19-2010, 06:20 AM
Spur washers are a goer in my opinion. They dig into what they are physically connected to. Thats what I used on the ground for my car and welder.

Same same thing as
steel lock washer ?

Copper paste, cant see why not, probably a bit much for the application.

Only my opinion.

A.K. Boomer
01-19-2010, 09:19 AM
Yes like spyguy stated - stay away from the di-electric grease (so no silicone bases)

Most other greases are a no-no also due to the fact that their job is to lubricate and this means it will try to keep the parts "away" from each other, in the application of a massive flat surface area like a washer it could prove counter productive.

You really do need a specific grease and it sounds like dockrat my have found one for you, I also know that when tightening the lugs that hold aluminum wire in panels that there is a very dark paste that is mandatory to apply to all the cable ends before tightening - don't know if its conductive but it is anti-corrosive.

Personally I would check into that black battery post terminal gunk they sell for auto's,,, high corrosion protection yet I dont think its keeps the parts away from each other like grease, Toss your copper particles into that stuff and and tighten everything down and I bet you have very good conductivity with an automatic seal.

larry_g
01-19-2010, 09:46 AM
IMHO you should ground to the MOTOR first and then jumper from the motor to the frame and all other points that need grounded. Running the ground from the battery to the frame and then frame to motor just adds two junctions to the start circuit that are not desired. To test your ground take a voltage reading from the negative post of the battery to the frame of the starter while starting the motor. If you have no voltage drop then your ground is in good shape. If you have voltage drop then there is resistance in the ground path that MAY need attention. GM had to replace some transmissions in the diesel rigs that had the starting current running through them because ground wire was not adequate to carry the current to the starter.

lg
no neat sig line

Willy
01-19-2010, 10:00 AM
I must be missing something here JR.
Once you have zero ohms loss across the junction and no voltage drop across the ground junction under heavy(starting) load, what more is there to gain? A simple dab of paint will maintain that intrinsic bond for a long time. An unacceptable voltage drop under heavy draw would be better helped by an increase in supply and ground wire gauge size.

pcarpenter
01-19-2010, 12:24 PM
The reason for using a conductive paste instead of a coating is that salt water will eventually make it's way under a coating like paint..trapping the moisture and allowing it to do even more damage.

The conductive "greases" are goopy and cling pretty well and prevent galvanic issues. The stuff I have came from the local home center (GB brand) and is designed to go on things like service entrance wire where it's clamped in panel mains. etc. I use this stuff regularly on battery terminals. Unlike the red spray-on stuff, it's conductive and still seems to prevent corrosion.

I had issues from the typical red battery terminal spray years ago. It would "melt" in hot weather, and ran down in and around the battery clamp on a post-type battery. The resultant high-resistance connection caused starting problems. I would pull the terminal, wipe the inside out and put it back and all was well.....just a bit of unsolicited trivia.

Paul

JRouche
01-19-2010, 12:33 PM
Great!! Thanks for all the replies. I have some napa (permatex) anti-seize here that has some aluminum in it. I will make a dryish paste with that and the copper and give it a shot. Thanks, JR

Oh, any other ideas what to use this copper powder for?? Gotta be useful for something?????

lazlo
01-19-2010, 12:41 PM
JR, I have some silver paste from work that's used for heat sinks on prototypes. It's highly thermally conductive, but unlike the consumer "silver" paste ("Arctic Silver" et al) that the kids use to overclock their PC's, it's also highly electrically conductive (i.e., it has a very high silver content).

It's very expensive, but I seem to remember that you could get a sample from the vendor. I'm in Santa Clara this week -- I can look up the brand when I get back.

vincemulhollon
01-19-2010, 12:46 PM
Once you have zero ohms loss across the junction and no voltage drop across the ground junction under heavy(starting) load

Yes good luck getting there, and its even harder to stay there...

Powdered copper is the wrong way to go. Check out the Penetrox series, for example Penetrox-A. A heavy oily grease to keep water out, a gritty substance to break thru any oxide layer while cranking it down (also helps prevent galling), and zinc to act like a sacrificial anode. Real electricians know all about this stuff.

$15 will buy you a lifetime supply in a tiny little bottle. Supposedly the grease goes rancid in a few decades. You will probably have to shake the bottle to mix it.

Alternately, find an electrician, you know, the guy with the dull 24 inch long drill bit thats too expensive to simply toss out, and make the obvious trade, a bottle cap full of the correct Penetrox grease for a nice professionally sharpened drill bit...

Note this Penetrox stuff is conductive. Don't put it inside multi-pin connectors or power outlets.

Boucher
01-19-2010, 01:05 PM
There are several commercial versions made originally for joining Al&Cu in electrical connectors. The one that I like the best is Ox-Gard in the small tube from Home Depot. I have it in all my tool boxes. Very good on marine battery connections. The copper in any grease will probably work. If I were doing it I would try some non hardning silicone grease like Dow 722 or water proof wheel bearing grease.

RPease
01-19-2010, 01:49 PM
Btw, if you're looking to dispose of some of that copper powder, I'll take some off your hands. :cool:


Spyguy........if you want copper powder, just file on some US pennies (dtd btw 1960 & 1982). They are 95% cu & 5% Zn.

5 lbs is only about $5 worth. :D

mcskipper
01-19-2010, 04:05 PM
On high current connections I have always used a Belleville washer then a flat washer under the nut. That spring washer will keep a tight connection as the copper expands and contracts under high current and cooling. I would use undercoat to waterproff the connection.

J. Randall
01-19-2010, 07:23 PM
This whole discussion seems to be centered around the grounds, when in reality you will have very little trouble there. Maybe you intended to use it on the plus side of the circuit also and it was not mentioned, that is where you will have the most corrosion and connectivity problems.
James

darryl
01-19-2010, 09:57 PM
Of course you want all of your connections to be solid, especially high current flow areas. I've seen many times a problem with the ground lead from battery negative to the frame in vehicles. Most times also, a heavy lead goes from negative to the block. That's another spot where that conductive anti-seize should be put. Then consider the starter mounting area- the high current has to flow through that to make it through the starter wiring. If there's a lug on the starter itself where it's own heavy wire is grounded, that's probably the point where the negative cable should go to. I've seen where a starter doesn't quite 'have it' when the mounting bolts aren't tight, and where there's crud between the starter and the engine.

If you're going to look at one high current connection, you might as well consider them all.