Big Three Upgrade

[TechNova]

wouldnt it be better to just ensure good contact without a star washer and to use a tiny bit of threadlocker? thats if torque was the concern. to mme the idea of using a washer, with less surface area, is asking for 1) more spots for corrosion to start 2) less contact . Like you said, coated, if you have proper surface to proper surface, a proper application of protective coating should fix the concern of future issues for a long time.

Locktite is probably not needed but can be used, Often body grounds are in sheetmetal so locktite isn't going to do much good with the small amount of thread engagement. Star washers are also lock washers, not as heavy duty as a true lock washer. I am guessing that the OEM concern about proper torque applies to sheetmetal. It is very easy to strip out the threads when using a lag type screw in sheet metal. The stud shown above solves the lo thread engagement issue giving better torque. In an engine block torque shouldn't be an issue other than the weight of the cable bouncing while driving can loosen a bolt. I try to route the cable to tighten or at least not loosen from vibrations.
The OEM use coated fasteners, dry coating, I can't see it on the ones I have in my drawer but was told they were coated. Adding a coating after install like paint, undercoat, di-ellectric grease is essential with a star washer to keep the corrosion points sealed. The star washer points help provide contact and prevent loosening by digging into the metal. The trade off is they need to be covered up to prevent corrosion.

 

[SAATR]

I can't imagine a carbon-laden paste has very low resistance. Yes, it might be "conductive", meaning it might provide a electrical path of a sort, but the resistance I would expect be on the order of 100-1000ohms or greater and, if so, that wouldn't help much in a automotive environment where the currents are typically in the range of 1-100amps.

Indeed, the product mentioned above "prevents static buildup"... which is a very high-voltage scenario in which a "conductive" paste with even 1megaohm path resistance would fill the requirement.

My $0.02

Smear some of that carbon grease on a piece of glass and stick the probes from an ohmmeter into it. Take a picture and report-back on what you've found.


It does reportedly "repels moisture, inhibits corrosion", which is good in an automotive application. They claim "Resistivity of 23Ω.cm"... not sure what that means because: Resistance is linearly proportional to the path length (OK, they mentioned "cm") and inversely proportional to the cross-sectional area (they mentioned nothing of this). Hmm.

It seems the purpose for using dielectric grease is to protect the connection from corrosion, and do so over a long period of time... I quote: "Permatex dielectric tune-up grease protects electrical connections and wiring from salt, dirt and corrosion."

Net-net IMHO (I've been wrong before so today won't be my first):

- either will suffice in the automotive application
- don't believe the carbon stuff will function any better

Here's the formula and explanation of the unit of measure:

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Here's the volume resistivity of the carbon based lube from the technical data sheet:

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And here's the volume resistivity of Permatex dielectric grease, also from their TDS:

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As you can see, that's 5.67x10^13 versus 23.

The volume resistivity of steel and copper are significantly lower than either of those, and obviously are carrying the vast majority of current in the connection.

But why fill all the voids and asperities in any electrical connection you make with something that is designed as an insulator, the definition of dielectric? It's nonsensical.

Given that most folks that are looking to do a "Big 3" upgrade are actually just looking for a functional starting and charging system, it makes sense to recommend a product specifically engineered to give a low resistance, corrosion free connection.

 

[1998_K1500_Sub]

The volume resistivity of steel and copper are significantly lower than either of those, and obviously are carrying the vast majority of current in the connection.

But why fill all the voids and asperities in any electrical connection you make with something that is designed as an insulator, the definition of dielectric? It's nonsensical.

Given that most folks that are looking to do a "Big 3" upgrade are actually just looking for a functional starting and charging system, it makes sense to recommend a product specifically engineered to give a low resistance, corrosion free connection.

@SAATR, I appreciate the detailed response.

The carbon lube seems to be as fine as dielectric grease as a means of preserving the integrity of a metal - metal electrical junction.

Your reference indicates the volume resistivity ρ of the carbon lube is many orders of magnitude lower than dielectric grease. I'll ask "Does it matter? Does it make it better?"

You rightly point out that "the volume resistivity of steel and copper are significantly lower". Let's compare them to the carbon lube.

First, I need to convert so I'm using common units with those of copper and steel. For the carbon lube, the value of ρ = 23 (Ω•cm) is equivalently ρ = .23 (Ω•m).

From Wikipedia I obtained the ρ values for copper and carbon steel.

Electrical resistivity and conductivity - Wikipedia

en.wikipedia.org

In common units, all three values are:

For carbon lube, ρ = .23 (Ω•m).
For copper ρ = 1.6×10−8 (Ω•m)
For carbon steel ρ = 14×10−8 (Ω•m)

This is better illustrated by moving the decimal point:

carbon lube, ρ = 23,000,000×10−8 (Ω•m).
copper ρ = 1.6×10−8 (Ω•m)
carbon steel ρ = 14×10−8 (Ω•m)

The carbon lube is ~6 orders of magnitude poorer, in terms of volume resistivity, than mild steel(!). That's telling.

So what is being accomplished, electrically, by using the carbon lube?
Well, what one is doing is effectively placing resistors in parallel, i.e., the resistance "R1" of the metal - metal connection in parallel with the resistance "R2" of the metal - carbon lube - metal connection.

"R1" is clearly much, much less than "R2", and putting them in parallel makes no practical difference, i.e., R1 || R2 = ~R1

So if we trust the numbers, using the carbon lube is an exercise in getting one's fingers greasy but does little to improve (reduce) the resistance of any reasonable copper - steel or steel - steel connection.

Having said this, I am certainly guilty of "fixing things that aren't broken" and "if a little is good then too-much is best", so I can appreciate the enthusiasm of using the carbon grease instead of dielectric grease.

But I'm willing to state plainly that the difference in performance will be practically immeasurable in the context of automotive electrical systems. Stating this differently, if a connection is improved by using the carbon grease, then it must have been a very poorly made connection from the beginning and will be unusable regardless. Thus, using the carbon lube instead of dielectric grease, from an electrical perspective, isn't worth the effort.

My $0.02

 

[AuroraGirl]

Here's the formula and explanation of the unit of measure:

You must be registered for see images attach

Here's the volume resistivity of the carbon based lube from the technical data sheet:

You must be registered for see images attach

And here's the volume resistivity of Permatex dielectric grease, also from their TDS:

You must be registered for see images attach

As you can see, that's 5.67x10^13 versus 23.

The volume resistivity of steel and copper are significantly lower than either of those, and obviously are carrying the vast majority of current in the connection.

But why fill all the voids and asperities in any electrical connection you make with something that is designed as an insulator, the definition of dielectric? It's nonsensical.

Given that most folks that are looking to do a "Big 3" upgrade are actually just looking for a functional starting and charging system, it makes sense to recommend a product specifically engineered to give a low resistance, corrosion free connection.

nerd

(said lovingly from a nerd myself)

 

[1998_K1500_Sub]

The link below points to an interesting story, written reasonably well, covering various greases used in various electrical applications.

The claims made in the story aren't surprising to me.

Dielectric Grease vs Conductive Grease

"Other articles tell people to use conductive grease on connections, such as between battery terminals and an automotive battery. Tests show this claim is completely wishful thinking, and the type of grease has virtually no impact on terminal-to-post voltage drop."

"Using aluminum and copper blocks with various surface conditions, I've never been able to actually verify connection improvement from specialized conductive greases."

"In bolted or clamped connections, I have no opinion if conductive greases help or are necessary. I feel like they help, but I'm not sure if that is true."

 

[SAATR]

My original source for my assertion that, to paraphrase, "thou shalt not use dielectric grease in electrical connections" came from a service bulletin from Caterpillar, for whom I work. It is as follows:

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That has been my scripture, chapter and verse, as long as I have worked for the company. Connectors of any ilk are installed with their pins and sockets DRY, no exceptions. In my zeal to find corroborating evidence of this practice outside Cat circles, I came across this article from TE Connectivity, who happen to make the Deutsch branded connectors common in Cat equipment. This is from their connector usage documentation, of which Note 1 is of interest:

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While this does back up Cat's guidance on the subject, I needed to see if any other manufacturer used similar protocols. Further digging uncovered this:

https://www.nyelubricants.com/service-bulletin-nyogel-760g

On that page, I found the following list of service bulletins and TSB's specifying Nye's 760G dielectric product:

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Lo and behold, Caterpillar is second on the list! After further investigation, I find the following:

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So apparently Cat engineering isn't immune to being wishy-washy on the subject.

Also, there are several references to GM TSB's that specify FLOODING connectors on certain modules with dielectric grease. There are similar TSB's from Ford that are not listed in this document. Obviously, there are vastly different points of view within the engineering and manufacturing sectors on the use of dielectric greases in electrical connections, but the prevailing wisdom seems to be that using it directly on conductors and contacts is perfectly fine. My bit of inductive reasoning from Cat to industry at large was wrong, and I stand corrected.

On the subject of the conductive grease, however, I must still respectfully disagree. I do agree that such greases do not improve clean, bright, solid, metal to metal connections. That was never in contention. I posit that they can and will decrease current draw due to pitted, corroded, warped, and otherwise poor fitting connections. Situations common in the starting circuits of vehicles and equipment in corrosive environments, or simply due to age and use. I have dealt with situations where cleaning and smoothing contacts was not enough simply due to damage from arcing or surface corrosion. Typically high amp starting circuits, like this one:

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A poorly formed crimp at the factory allowed arcing in the wire, which overheated the starter terminals and caused a no-crank condition. The broken wire was cut to clean copper, a new lug crimped on, and the starter connections were removed and cleaned. Unfortunately, there was heat damage to the terminals, pitting, and surface deformation that I could not readily fix. A new starter bridge cable and a new starter solenoid were required, as the amp draw was still peaking too high during cold crank, and there was arcing in the connection. I applied the carbon paste, sparingly, and the arcing stopped, and the current draw dropped about 50A. Still too high, but the starters were able to spin the engine fast enough to start. The substance does work but, again, it will not improve clean connections. Dielectric grease would not do that, and has no chance of actually helping the connection, only protecting it.

 

[SAATR]

And some math, based on the 23 ohm cm volume resistivity figure. I'm not sure where to dig up the unicode for rho and ohms, so I'll just post a picture.

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In case my handwriting is totally illegible, that's an area A of 1 square centimeter, and a film thickness of .005" or .0127cm. The final resistance figure of the joint is 0.29 ohm.

The film thickness and area of the layer are obviously arbitrary, but the idea stands. It isn't magic, and it isn't ideal, but it does work and can improve marginal connections.

 

[1998_K1500_Sub]

The film thickness and area of the layer are obviously arbitrary, but the idea stands. It isn't magic, and it isn't ideal, but it does work and
can improve marginal connections.

Ah, the tyranny of numbers. Which numbers are good? Which are bad?

I like your approach and I like your result. Now I want you to carry it one step further. I'll help...

A .29Ω resistance will yield a .29V drop when 1A flows through it, or 2.9V drop @ 10A (Ohm's Law, which I'm pretty sure you're acquainted with). That's hardly useful in an automotive environment in the context of this thread (low voltage drop / high-current circuits), and it's not going to improve (much) upon the .005Ω - .001Ω resistance of a metal-metal connection... that was my point in my earlier discussion when I mentioned that the two resistances in parallel ("R1" of the metal - metal connection in parallel with the resistance "R2" of the metal - carbon lube - metal connection) won't be any better because one of them is so large compared to the other (R1 || R2 = ~R1).

Just for the sake of numbers, .29Ω in parallel with .005Ω yields .004915Ω, an almost insignificant improvement.

The .005 film thickness you assumed is reasonable to me and could arguably be lower, with a proportionate reduction in the resistance you calculated and which I've called R2, but it's still not very low.

A .29Ω resistance would be tolerable in a signal path, e.g., the circuit containing a sensor, but that's not the topic

Meanwhile, I scanned but have yet to study your post just prior, with the references to Caterpiller and TE Connectivity, and also to your field experience with at least one starter. It looks like an interesting read and I will likely comment.

 

[1998_K1500_Sub]

Let's study this (below). It's a very good example and relevant to the automotive scenario.

A poorly formed crimp at the factory allowed arcing in the wire, which overheated the starter terminals and caused a no-crank condition. The broken wire was cut to clean copper, a new lug crimped on, and the starter connections were removed and cleaned. Unfortunately, there was heat damage to the terminals, pitting, and surface deformation that I could not readily fix. A new starter bridge cable and a new starter solenoid were required, as the amp draw was still peaking too high during cold crank, and there was arcing in the connection. I applied the carbon paste, sparingly, and the arcing stopped, and the current draw dropped about 50A. Still too high, but the starters were able to spin the engine fast enough to start. The substance does work but, again, it will not improve clean connections. Dielectric grease would not do that, and has no chance of actually helping the connection, only protecting it.

You mentioned "A new starter bridge cable and a new starter solenoid were required, as the amp draw was still peaking too high during cold crank."

Hmm... well, a compromised cable and solenoid would increase the resistance of the circuit, causing....

- a reduction in total current

- heat in the cable (most notably in the area of higher resistance) and

- heat in the contacts of the starter solenoid and / or arcing if the contacts were in poor condition

- reduction in performance of the starter motor because of the added resistance in the circuit due to the items above

The increased resistance of the cable and solenoid contacts would have reduced the current ("amp draw") in the circuit, not increased it ("the amp draw was still peaking too high during cold crank"), so there's some disparity, here.

You said "I applied the carbon paste, sparingly, and the arcing stopped, and the current draw dropped about 50A". Explain to me where you applied the paste, exactly. A 50A current draw is low in a starter circuit, akin to that of simply the solenoid. Also explain where the arcing was occurring, as the carbon paste may have simply mitigated the arc (i.e, if the carbon paste reduced the resistance of any connection then the current should have increased)

I can speculate more, but I'll ask you to reflect on what you wrote earlier and make sure it's accurate, because something seems amiss.

I think this is a great story and would like to get to the bottom of what really happened and the paste's role (arc mitigation? lowered resistance?) in the outcome.

 

[Erik the Awful]

I like my connectors clean and dry with no lubricant. If there's a problem with water intrusion, dab some dielectric grease into the connector and snap it back together. I see no other reason the average truck owner needs to worry about this stuff.