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Use solder paste on terminals-busbar to improve conductivity?

I normally use copper for bus-bars and terminals.

The issue is that the battery terminals on these are aluminium. There are a couple of issues with that. For one, aluminium oxide is not a conductor, so the terminals should be sanded before use (this, by the way, is also mentioned in the datasheet). However since this oxide is formed very quickly, you should do this while applying some sort of grease to seal out air to prevent this. Additionally, putting copper in direct contact with aluminium leads to galvanic corrosion.
In addition, you can combine this grease with a conductive filler to make a very good contact. I'm experimenting with carbon conductive paste (MG Chemicals 847) with some very good preliminary results.
 
You beat me to it :)

With Copper to copper, oxidation isn't much an issue. Under tention/pressure/ compacted the oxidation on both surfaces doesn't behave like insulation.

Aluminium is way different, in a few seconds after cleaning (removing the old oxidation) new oxidation is getting formed up to a level where it has enough insulating properties to have effect on the connection.

I now have Ox-gard what works really amazing.

Vaseline, di-electric grease and all that other stuff works fine on copper.

Not aluminium.
Absolutely different approach, can't even start to compare, besides it both conduct electricity.

2 metals will easily give galvanic corrosion. Adding a third as sacrifice (zinc, tin, magnesium) will help/ prevent.
(Electroplating or other method to apply layer)
 
Will it make that much of a difference? I have never had to use any grease or paste on connections, unless they were exposed to weather somehow, never had a situation where it was called for. I just make sure that the contact surfaces are clean and flat and torqued down to spec. Every once in while I spray some stuff on our car battery terminals and it keeps them clean. Your application could be different. I normally use copper for bus-bars and terminals.
Google "galvanic corrosion".

Aluminum oxide is a terrible conductor, and the action of galvanic corrosion will make the interface of copper and aluminum preferentially corrode the aluminum terminal.

Now, if you live in the desert like myself, it is probably not as big a concern as anywhere else. If you live in a high humidity environment, you will be affected within a couple of years.
 
Yeah I try to stay away from aluminum when ever possible. And I do leave in the dessert too.
 
I read a few pages. Flux is acidic. Dielectric grease keeps voltage from leaking between terminals. Vaseline becomes white waxy powder. All true

spray Fluid Film on things after tightening your connections. Clean-to-clean. And aluminum will need periodic maintenance of it’s sandwiched to copper.
Anything you put between bolted conductors other than conductive grease is detrimental imho. WD40 is a short term solution but Fluid Film lasts a long time.
 
I am totally tripped out on how much a simple suggestion like anti-oxidant use produces! :)

What we know:
At our terminal is a wide variety of dis-similar metals. Perhaps aluminum terminals, stainless bolts, copper/nickel busbars, and a few weedy little steel bms balancing eyelets.

That's one thing. Go to any home improvement store in your area, and you will find some sort of ***LOX tube. It's not for your bagel breakfast, but typically for homes (older) that have aluminum wiring and more modern copper outlets. Depending on where I go, I find either PeneTrox, or NoAlox.

Specifically designed for dis-similar metal connections.

The secondary benefit with a LIGHT coat on flat surfaces is to keep out natural oxidation from the air we breathe. NO matter how tight you get it, it still gets in.

(Does anyone have any thin busbars "double-upped" on each other. Pull them apart after a few years, and take a look.)

The actual issue, other than minute amounts connections going higher in resistance over time, is that these higher-resistance connections add up to your cell's own internal resistance, and may fool balancing.

Super-bad connections where things melt are one thing. But in my weedy little installs, I don't want the balancers getting fooled by the additional resistance and not treating the cells like they should over time.
 
Maybe this will help out the younger folk. :)

I use NoAlox out of an abundance of caution with my dissimilar metals, mostly so that very minute amounts of additional resistance in series with my cells doesn't make the bms balancers work harder than they have to or mistreat the cells a few years down the road.

BUT - for most "modern" aluminum alloys you dont HAVE to. But I don't actually KNOW what type of aluminum alloy my cells are using! So I play it safe.

One of the most intelligent vids on this subject is right here:

WARNING!! There is a bad word or two thrown out.



The takeaway is

1) Most modern aluminum alloys don't need it.
2) It is often applied improperly
3) Not mandatory in some areas
4) But will not hurt if you do.
5) Might make diy LiFeP04 setups and their bms balancers not work harder than they need to. (he forgot that!) :)
 
He indicates local circumstances so that’s regional based on whether your local environment makes it useful.

in northern New England I’d use it.
Or what I’ve been doing for at least five years now: spray-can Fluid Film after assembling cleaned battery terminals or low voltage junction boxes, terminal blocks. Even on utility trailer and RV wiring. Nasty, messy, terrible to work on later BUT I haven’t needed to fix a single thing I’ve done that to. Assemble clean, lock out oxygen.
He also said “nobody” cleans terminals and wire...I’m also a nobody I guess.
 
Hi fhorst
I just bought some Ox-Gard at Home Depot here in Canada if that helps. :)
I realize this is an old post, but here's my two scents this material is anti corrosion but has no conductivity properties even though it states it does, in my opinion. I have been using a paste in automotive application that is I believe to be composed of Dielectric grease and carbon dust materials it is not cheap but works real well and conductivity when tested with a Fluke Ohm reading was 0.05 at that time.
 
I realize this is an old post, but here's my two scents this material is anti corrosion but has no conductivity properties even though it states it does, in my opinion. I have been using a paste in automotive application that is I believe to be composed of Dielectric grease and carbon dust materials it is not cheap but works real well and conductivity when tested with a Fluke Ohm reading was 0.05 at that time.
Here's my thought.

Ox-Gard, Noalox, etc. have been used and accepted by electrical inspectors for more than 40 years. They are cheap, and don't cause shorts if they drip. Done.
 
Yeah,

We have seen several hundreds of different *excellent conductive and corrosion prevention* grease.
Some "home (small Factory) made, some from large companies.

We know that professional LiFePO4 installers in telecom use silver based paste, not our price class...

Almost all other installers use noalox or ox-guard, and with good reason, approved by most inspection regulations.

Almost all others of the Hundreds are, with good reason, not approved by most inspection regulations.

Naturally, feel free to use what ever you like.

If you need any approval, better stay on the paved road side.

Personally, I really would have liked to use that silver based.
With a price of $230 (ex transport and taxes) for a small jar, and 160 terminals that's not going to happen.

It will never match the stability from laser welded aluminium Bus-bars, packs of +/- 50 kg, with strong and large enough contact points..

Instead...
We are dealing with grubscrews in weak aluminium and copper plated Bus-bars to mimic this, but won't even get close.

We don't need to, as it's solar, and not heavily loaded.
Perhaps 400-500A, like my setup, most won't pass the 200A.
None will go in the regions EV would drain (+2100A@51.2v)(or 700A @144v), what needs different levels of contact.

I tried a few of the "hundreds", being thick headed, stubborn, or ignorant or... Just me?

Anyways..
Now I use ox-gard and that finally works, as it should and none of the others did.

As many have gone before me and many will go follow as it is a (the?) best available working solution.

Please try, and inform us of the progress of the carbon dust.

Till then, folks, don't be an idiot like me, and just follow the paved paths.

The need for several remounts will cost you your threads, for what I have made excellent guide on how to repair :)

Your not the first that's making a DC contact, and you won't be the last.
It's done for many decades, don't try to reinvent the wheel that is round and running smoothly :) for decades.
 
Regarding using silver paste, here is a video of an electrician talking about using Noalox anti-corrosion paste to improve the long-term conductivity of a cable crimp:

Noalox claims to "penetrate and cut aluminum oxidation improving efficiency and service life of aluminum electrical connections".
 
Thanks for the video,
Noalox and oxi-guard do about the same, and both are approved by most regulations.

I'm missing the link with silver here,
I did not hear them about it in the video.

Good idea to put antioxidation for crimping wires!
As "all" lugs are electroplated copper, I don't really see the benefit here, but it won't hurt, that's for sure!

Noalox / oxi-guard aren't "good" enough to put bare copper on aluminium.
That will give galvanic corrosion.
It probably will delay it some, but without middle metal like tin, zinc or nickel... You have a probelm (in time)

For this thread is/was not so much about crimping, more about the terminal - bus-bar connection, and how to get that most optimal.

Most optimal stays zilver, second best shared is oxi-guard/noalox :)
 
Noalox / oxi-guard aren't "good" enough to put bare copper on aluminium.
That will give galvanic corrosion.
It probably will delay it some, but without middle metal like tin, zinc or nickel... You have a probelm (in time)
Right. Noalox is anti oxidation stuff; any unequal material electrical or water connection will corrode regardless of preventing air “contamination”
 
Right. Noalox is anti oxidation stuff; any unequal material electrical or water connection will corrode regardless of preventing air “contamination”
Just asking a question from someone who doesn't know ...... doesn't oxidation require oxygen ... and maybe humidity?
 
Just asking a question from someone who doesn't know ...... doesn't oxidation require oxygen ... and maybe humidity?
Yes, that's why both products (ox-gard and noalox) are designed to exclude air and water from the join.
 
So much combined knowledge here I don't want to miss the chance on asking.

For LiFePO4 higher Amperage cells you connect the terminals with bus-bars.
Bus-bars that are bolted onto the terminal.

I personally use headless bolts as they place less stress at he weak shallow aluminium thread (only 6mm deep and max 8Nm torque!!!)

Anyway, to improve connection between bus-bar and terminal they obviously need to be cleaned and flat as possible.

I read that professional installers use silver electricity conductive paste. Expensive stuff!!

Many people use nothing in between.

Would something simple as solder paste improve the connections between the terminal and bus-bars??

Solder paste flux is non-corrosive
Solder paste have about 50% solder.

Naturally, a really thin layer, just to maximize conductivity.

It won't be as good as silver, but I think a lot better then nothing!

Positive is that it's easy to obtain, easy to use and not crazy expensive!

Both terminal and bus-bars (this is not yet bus-bar, now just copper bar) have minimal damages and the terminals have circles.
View attachment 20490
View attachment 20491
Flatening by filling the mini gaps should improve total contact surface, yes??

Or is it a dumb idea??
And if it is, why?

I already have 1.4ml silver conductive paste, and use this.
Probably won't be enough....
The order from 3 * 2.5ml turns out to be 3 * 0.2ml....
That will go back to the shop.
Price wasn't like 0.2ml
Here is an interesting read: https://www.practical-sailor.com/boat-maintenance/conductive-greases-vs-corrosion
 
First picture, first thing I notice is the tube of "Super Lube" which is a thermal transfer compound that is not conductive (hence it is called a dielectric).

Commonly used with an insulator for high power components to insulate them, yet thermally conduct to a metal heatsink.
Please do NOT use this on any connections. It belongs as a heatsink compound in your switching power supply, but not anywhere near your battery terminals.



Also, unless you are on a boat, keep seawater away from your connections, it will corrode anything.

This 10 year old article is interesting:


I'm not finding testing in a solution of 30% saltwater to realistic test conditions, unless you are on a boat with a leak.
Unless you are within sight of the ocean, shouldn't be any saltwater, even in humid air. Saltwater will corrode pretty much ANYTHING.

Interesting that the article you linked, and the article that is 10 years old (and linked in the one you posted) came to such different conclusions.


"Best Anti-corrosion Coating

Noalox (aluminum wiring corrosion preventative) and No-Ox-Id (terminal grease), out performed all others by a wide range."

vs

"However, it actually accelerated corrosion on the copper and solder test samples, which were significantly damaged."

Test procedure that says Noalox is bad:

"To find out, we modified a rock tumbler to provide a gentle washing. Testers filled the tumbler jar about two-thirds full with brackish water and mounted a bundle of standard metal samples (coupons) to one end. Aluminum, copper, and brass are galvanically coupled in one sample set, and cast iron and cold-rolled SAE 1020 steel are coupled in another sample set. The setup insulates the two coupon groups from each other, the tie bolt, and the brass legs.

Testers applied a uniform, thin coating of grease to each sample coupon and allowed the coupons to gently splash in the tumbler for 10 days; testers changed the water and cleaned the container daily to minimize grease re-deposition. We then observed and measured both corrosion and remaining grease coatings."

Test procedure that says Noalox is the best:

Unfortunately the testing used in the "best anti-corrosion coating" won't let me cut, it's a PDF.


I think the key difference is not being put in a rock tumbler.

Screenshot 2021-07-15 195432.jpg
 
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I'm experimenting with carbon conductive paste (MG Chemicals 847) with some very good preliminary results.
I recently reworked my bus bars with this material (along with nickel plating the copper). The improvement was significant, with cell IR deltas dropping over 50%.
 
I recently reworked my bus bars with this material (along with nickel plating the copper). The improvement was significant, with cell IR deltas dropping over 50%.
You do realize that carbon coated aluminum is part of the chemistry that makes LiFePO4 work, right?
 
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