Electrical Contacts: conduction improving agents

[DingusMcGee]

Electrical wires in operating ebikes corrode, but not all claims of satisfactory conducting agents lead to what will work well for the low and high DC voltage contacts of these machines.

Dielectric grease. Why not? It is non conducting.

[AC]Electricians use:



High DC voltages contacts can use some forms of anti-ox, but GB OX-Guard changes state with DC current and eventually or soon works quite poorly for conducting when DC contact interfaces are coated with it.

The FIX

Clean all contacts that have been coated with substances like GB Ox-Gard, Dielectric Grease, NoAlox and the likes. If the coating agents contain silicone, removing the compound may be difficult.



What agents are suitable for enhancing DC current flow?

I say carefully choose - - - -an Electrical Contact Grease product— Google will pull up non-conductors when queried by this word group. Our world of getting and giving CRAP.

A good electrical contact grease:




Or for an Amazon USA version see:

https://www.amazon.com/MG-Chemicals-Carbon-Conductive-Grease/dp/B005T8ROWA?th=1

These contact conduction enhancing greases are messy as they have a low viscosity, are very tenacious and so will smear easily. Conduction becomes everywhere there are connected smears — especially a problem for low voltage multiple wire connectors.

You have to be very discrete when applying these conducting greases to low voltage contacts like the Hall Wires. Any grease left on the plastic face surface of the female contact set can leads to a short circuit of these wires. Whereas such wiped thin coating on the Phase Wires will burn off these connections.

But it is false to think that a thin coat of GB Ox-Gard will burn off on phase wires.

 

[E-HP]

DeoxIT seems to work well on connectors, as well as switch contacts and potentiometers. I haven't tried many other products.

 

[Chalo]

Any conductive coating presents the possibility of exaggerating galvanic corrosion. Dielectric grease is better to use where dissimilar metals or platings come into contact with each other.

 

[DogDipstick]

Penetrox makes a full line of compatible metal to metal contact and conductivity improving compounds that make noble table dissimilarity work well together. Stopping all galvanic corrosion of the precious conductors. In its tracks.

Certainly always conductive on errything high current ... but except low current sensor wires, brake cuts hall hookups, throttle, they get dielectric for me.

Copper to aluminum., Copper to copper. Copper to silver. Copper to steel. Aluminium to steel. You name it. Made to specifically stop galvanic corrosion. Well known by millwrights, tradesmen, and mechanics.

Example line of product ( Made in the USA too), one of many PENETROX makes.

https://objects.eanixter.com/PD372804.PDF

( Also: required to be used in many circumstances, by the NEC, quite possibly in your area... )

 

[liveforphysics]

Unfilled dielectric gels and greases actually measure lower R joints in the last few hundred tests I've ran.

I even tried to do my own filled grease with single wall carbon nanotubes and one with micronized silver metal. Both performed worse than unfilled dielectric grease/gel.

 

[DogDipstick]

Unfilled dielectric gels and greases actually measure lower R joints in the last few hundred tests I've ran.

I even tried to do my own

Longevity, cost too? Given environment ( where "it" is) or economy ( what "it" is and what "its" cost was) ?

Or just current handling? What did you ( exactly... ) test? All those things?

I would love to see the results. Bah .

i wonder whey it is required, per so many codes around the nation. Shrug.

I know it is required in most 2017 codes around here.

Do they use dielectric grease on the high current connection in a modern EV? Or a conductive filled grease? Do they leave it bare?

What do they do ( coat with) about the copper to aluminum connections in permanent assembly? For longevity? Might I ask? In a modern EV battery? Is it just bare? I know a typical EV pack is filled with copper in direct contact with aluminum. Perhaps a special alloy? From what I know they coat the whole tab in some kind of oxygen blocking film? Post weld. I dont know though. Just what I think I have seen. I dont know.

 

[liveforphysics]

We have 5,600Amp CC-CV supplies and 7.5digit nano-volt meters at our lab I use to test.

The most important function is to displace humidity and vapor from the clean contact surfaces. Many have corrosion inhibitors to further reduce rates of corrosion.

All the filled greases I tried just had things in the way of the joint conductivity path and performed worse than a clean dielectric gel/grease.

 

[DogDipstick]

We have 5,600Amp CC-CV supplies and 7.5digit nano-volt meters at our lab I use to test.

Many have corrosion inhibitors to further reduce rates of corrosion.

Ok but do you have salt covered roads, other vehicles kicking up dust, and mass fractions of water vapor i the testing environment ( humidity control and temp swings) ? Do you test that with your fancy testing machines? Your 7.5 nanodigit meter? Can tell long term performance in salty roads in the winter of Alaska or heat of Alabama summer by the Gulf? Your 67,000 amp data helps there? Doya test that?

Did you do .. any long term performance testing in inclement environments?

... Real world data? Or are we just quoting the lab data?

last i checked its ot a perfect world.. ? What good is a " clean bright joint' when we all know it might tarnish in the enviroment and performance ( of the conductor) drop to nil... ( and or dangerous levels creating hotspots in the high current line.. and inherent connections... ie why the goop is required by NEC... to prevent that long term)?

I can vouch for the Penetrox.. I put that on a bright, shiny surface.. Dont put it on another...Set it by the seaside, and come back in three years, and one will still be bright and one will tarnish... Road or sea sald does not get inside the connectrions i slathered in Penetrox. The bare one will be green with verdigris by then. Whats it matter tho.

I guess those " tenths and hundredths of a milliohm " impeding the current dont matter much. If the circuit conductor is covered in verdigris.

Can you r meter measure that? nano digit meter? luke? the difference in conductivity of verdigris covered conductor, vs a weather protected sample?

....is it that sophisticated? That lil testin machine?

Wonder why it is so adamantly required in most code books. Shrug.

I suppose they leave it " bare" on a real EV battery assembly?

I wonder why those four Chevy Volt modules out in the shop, that i have, have not acquired any rot?

They certainly oxidize when I clean the tabs with sandpaper and let them sit exposed for time. Oh yeah those tabs corrode if left to the environments. However, something in the OEM module keeps that from happening.

Shrug.

 

[liveforphysics]

I do test joint performance in extreme conditions.

High G force vibe, multi salt blend salt spray testing and temperature cycles from -140degC to +100degC.

We also use much more extreme mixed corrosive acid vapor exposure tests, which tend to destroy all the metal parts that aren't covered in a film of dielectric grease/gel.

 

[liveforphysics]

With respect to precision, I test tiny connectors at 10Amps R measurement, medium connectors at 100Amp, and beefy connectors at 1,000-5,0000Amps.

With the voltage drop across the joint instrumented with the Nanovolt meter, I'm able to see changes in resistance repeatably at 0.0001mOhm or 0.1uOhm.

Coppers resistance change with temp becomes the biggest factor in repeating the readings, even 1degC warmer copper clearly shows its R change.

 

[DingusMcGee]

There are two regions of electrical conduction impeding processes/sites that happen in, on and around electrical contacts.

1. The zone on a contact that is the pathway for current carrying likely does better at conducting with a conducting grease applied to it’s mating surfaces. The connection must have a lower resistance after adding the conducting grease. But does adding a conducting grease to contact surfaces lead to faster corrosion of those surfaces? It is all about what happens at the boundary. Does that coated surface enhance stray ion transfer? If so, follow step 2 below.

And yes a two different metals contact zone often does better with some special conducting mix designed to work with both metals.

2. The zone which lies just beyond the contact zone must not have conducting grease or other current flow enhancers. Substances that prevent ion/electron transfer will arrest contact surface corrosion/degradation. This region can, when suitable, use water-proof connections. The 6 pin mechanical waterproof connectors that are used for Hall wires on some modern controllers does not need any external non-conducting coating or dielectric grease to stop corrosive agent transfer.

A well sealed mechanical connector:





https://www.ebay.com/itm/6-Way-Pin-Automotive-Car-Connector-Plug-Electrical-Sealed-Waterproof/195331575383?var=495101629749&pageci=4fa25133-5cb2-459a-b5c2-00c3b49070e2&redirect=mobile

Gold contacts do not corrode, But the metals that hold the gold may corrode. Which treatments then?

Likely a zone 2 treatment as I doubt there is a single substance that both enhances electron transfer and then does a good job at stopping stray ion transfer. Yes, when it comes about, it will be called a “smart” material, DNA?

 

[liveforphysics]

Ive tested this type of connectors sealing. It only passes corrosive vapor testing when it's packed with dielectric grease inside the cavity.

Gold plating only buys a few volts of electrolysis. Little round wire seals mating into square connector body ports has never passed a vapor sealing validation test for me yet.

Remember, passing IP67 or IP69 is super easy, as it's liquid water. Passing vapor intrusion testing is what it really needs to live in wild, that style pin sealing will not do it without being packed with dielectric grease.

 

[DingusMcGee]

liveforphysics,

Thanks for vapor intrusion issue detail of the 6 pin plug I mention.

For zone 2 protection, how does the thermal glue enhanced heat shrink tubing applied with a tight fit to single wires hold up to vapor intrusion? It does seem to [am I getting serious vapor intrusion?] work with most ebike power connections.

Additionally, how good of a vapor seal does one get when covering single wire connections with silicone or urethane sealants. Sealants that bond well to the various wire coverings.

Vapor intrusion: is the problem mostly water vapor or low concentration acidic vapors?

 

[DingusMcGee]

Plugs aside it seems our vapor expert has vanished and dropped the ball of this topic?

So be it, I will make a statement of my mildly empirically gained knowledge of lessening vapor intrusion — no pico meters used here.

If you want good conduction in those Hall Wires under “wild” environmental conditions, get rid of any form of a plug. You are wasting your time testing plugs under these condition for if you succeed, the wild environment status is made harsher — the Catch22 of life recurring.

Simply soldier those bastard wires and as a prophylactic measure cover ‘em with thermal coated heat shrink. But any dyke can cut ‘em faster than you can separate the ultimate vapor sealing male and female plug combination.