Avoiding Galvanic Corrosion

[HRTKD]

I'm new to welding aluminum, so I'm passing on what I've been taught in that area. The acetone isn't just for contamination. The oxidation layer on aluminum can make it hard to form a puddle because the melting point of the oxidation is much higher than the base aluminum. That's what I was taught.

Using acetone to wipe the terminal clean should help remove any debris from sanding. The nature of the acetone - to me - indicates that it won't leave a residue.

 

[noenegdod]

I'm new to welding aluminum, so I'm passing on what I've been taught in that area. The acetone isn't just for contamination. The oxidation layer on aluminum can make it hard to form a puddle because the melting point of the oxidation is much higher than the base aluminum. That's what I was taught.

Using acetone to wipe the terminal clean should help remove any debris from sanding. The nature of the acetone - to me - indicates that it won't leave a residue.

Im afraid you either misunderstood or the people that were offering up information didnt understand. Acetone does not remove aluminum oxides, that is the job of the wire brush, other form of abrasion or chemical action (of which acetone has none) such as Alumabrite. Acetone is simply a degreaser/solvent that leaves very little behind. Wiping after abrading with acetone is a viable way to remove oxide dust however there is a risk of leaving lint behind on the now rough surface. If you are going to use acetone in this way your better off flushing it. Just blow or brush it off, as said before, any additional oxide formation that may happen as a result of using compressed air is inconsequential. If your at all concerned about blowing it off, dont blow it off with your breath. You will condense moisture on the work and that would be of significantly more consequence (still really not that much) that using compressed air.

 

[Luthj]

The thin aluminum oxide layer that's present on the surface of new-ish terminals isn't going to impact contact resistance. What is more important is that the bus bar surface is flat and very clean of dust etc.

Even if you abrade the oxide layer off (only a few molecules thick), it will return in a few seconds typically.

Using any coarse abrasive is a bad idea. 600+ grit is okay.

 

[Bob B]

Im really curious, The purpose of using a solvent to wipe the surface of an aluminum weldment is to remove grease and oils from the surface so that once you strike the arc and establish a puddle, you dont contaminate it with those hydrocarbons. Why is everyone wiping the terminals with acetone or alcohols (with water in them)? I am asking this because many people subsequently smear an antioxidant on the surface. Is wiping with a solvent just a procedure from the welding industry that has carried over but doesnt really have any practical value?

My cells came with tape over the terminals. Once that tape was removed, I could see residue on some of the terminals from the tape .... So, I cleaned mine with a goo-gone product first to get that residue off and to make sure when I used emery cloth to gently rub the terminals and bus bars that I didn't rub that residue into the terminal.
My last step in the cleaning process was to wipe everything with a mildly damp cloth with 190 proof Everclear that I have been using in my home made hand sanitizer to remove any of the abraded material.

 

[noenegdod]

The thin aluminum oxide layer that's present on the surface of new-ish terminals isn't going to impact contact resistance. What is more important is that the bus bar surface is flat and very clean of dust etc.

Even if you abrade the oxide layer off (only a few molecules thick), it will return in a few seconds typically.

Using any coarse abrasive is a bad idea. 600+ grit is okay.

I agree completely

 

[noenegdod]

My cells came with tape over the terminals. Once that tape was removed, I could see residue on some of the terminals from the tape .... So, I cleaned mine with a goo-gone product first to get that residue off and to make sure when I used emery cloth to gently rub the terminals and bus bars that I didn't rub that residue into the terminal.
My last step in the cleaning process was to wipe everything with a mildly damp cloth with 190 proof Everclear that I have been using in my home made hand sanitizer to remove any of the abraded material.

The final step in the directions for googone products is to wash with hot soapy water.......

 

[Bob B]

The final step in the directions for googone products is to wash with hot soapy water.......

I think I used the Everclear after the goo-gone .... before and after the emery cloth. The Everclear seemed to leave a residue free terminal.

I was more trying to answer your question about .... why use a solvent. In my case it was tape residue

 

[Luthj]

Acetone, lacquer thinner, xylene, and 95% isopropyl are all okay choices. Be aware that adhesive residue won't come off with alcohol though.

 

[Bob B]

Acetone, lacquer thinner, xylene, and 95% isopropyl are all okay choices. Be aware that adhesive residue won't come off with alcohol though.

You are correct that alcohol won't remove the tape residue ..... I tried alcohol and acetone on another surface before I cleaned the tape residue off my terminals .... neither one of them removed the tape residue.
That goo gone is a great product. I didn't look at the label to see what the active ingredients are .... need to go look at that bottle again.

 

[HRTKD]

You are correct that alcohol won't remove the tape residue ..... I tried alcohol and acetone on another surface before I cleaned the tape residue off my terminals .... neither one of them removed the tape residue.
That goo gone is a great product. I didn't look at the label to see what the active ingredients are .... need to go look at that bottle again.

Xylene is in Goo Gone or one of the similar products, like Goof Off. I think it may also have acetone. I used a mix of those products on my RV when removing silicone caulk. Those products don't remove the silicone, but they do seem to release the bond the silicone has on the surface. I'm slowly eliminating all the silicone on my RV. It's a lot of work.

 

[fafrd]

I started this thread and see it has found a second life in my absence.

I have been balancing and capacity testing using standard busbars and have not been doing anything as far as treating/cleaning terminals (just checking that I’m putting the busbars on with any burs facing up).

Has anyone characterized how large of a difference any of these cleaning/treating steps has on characterization of new cells?

Doing things ‘right’ for final battery assembly makes sense but it sounds like a lot of trouble when connections are being moved around during the characterization phase if it’s not going to make much of a difference.

So advice appreciated from anyone who has done anything special to their terminals and/or busbars during top balance & capacity testing - was it worth the trouble?

Any suggestions on making connections good enough for successful top-balance and/or capacity test appreciated...

 

[Bob B]

Xylene is in Goo Gone or one of the similar products, like Goof Off. I think it may also have acetone. I used a mix of those products on my RV when removing silicone caulk. Those products don't remove the silicone, but they do seem to release the bond the silicone has on the surface. I'm slowly eliminating all the silicone on my RV. It's a lot of work.

The label doesn't have any active ingredients listed .... but it smells a little like kerosene.... may just be expensive diesel fuel.

@fafrd .... When I can look at the terminals and see residue on them.... I didn't see any need to do a before and after test. Common sense says clean that crap off first. The whole cleaning process is quick compared to other things that have to be done building the pack. It probably only took me about 5 minutes to clean and rub the cell terminals and bus bars with emery cloth on the 8 cells I used.

 

[HRTKD]

Bob, you're right. Goo Gone does not have Xylene. MSDS for Goo Gone.

I was using Goof Off Professional which does have Xylene and Acetone. MSDS for Goof Off.

 

[Hedges]

https://oregoncoast.edu/wp-content/uploads/files/maintenance-and-janitorial/goo_gone.pdf

JP-TS AVIATION FUEL (cas 64742-47-8) SDS/MSDS download

JP-TS AVIATION FUEL CAS 64742-47-8 SDS including Hazard identification, Composition/information on ingredients, First-aid measures, Fire-fighting measures, Accidental release measures, Handling and storage, Exposure controls/personal protection, Physical and chemical properties etc.

www.guidechem.com

Exactly which "light petroleum distillates" isn't specified.
Perhaps also marketed under the name "Tap Magic" as well as "Kerosene"?

"It's an aluminum cutting fluid AND a degreaser!" (with apologies to Saturday Night Live)

 

[fafrd]

@fafrd .... When I can look at the terminals and see residue on them.... I didn't see any need to do a before and after test. Common sense says clean that crap off first. The whole cleaning process is quick compared to other things that have to be done building the pack. It probably only took me about 5 minutes to clean and rub the cell terminals and bus bars with emery cloth on the 8 cells I used.

OK, guess I’ll be the guinea pig - I don’t see any ‘residue’ on any of my terminals, but many of them have small visible scratches and probably some oxide.

if the recommended ‘treatment’ to clean off an aluminum terminal is to lightly sand with emory paper, that sounds reasonable.

I’ll take one of my outlier cells tested without cleaning and retest with cleaning to see whether it has any impact on the result.

 

[noenegdod]

I think I used the Everclear after the goo-gone .... before and after the emery cloth. The Everclear seemed to leave a residue free terminal.

I was more trying to answer your question about .... why use a solvent. In my case it was tape residue

It was more of a rhetorical question to get people thinking, not that I dont appreciate the answer . It makes perfect sense to remove adhesive and you need to use a solvent for that. Googone wouldnt be my first choice, personally Id use a straight solvent like acetone or xylene to prevent any of the residue that they are recommending washing as the last step to get rid of but that is just me and to each their own.

The question was posed mainly because the solvent wash seems to be mostly a "monkey see monkey do" practice adopted from welding trade which has little to no relevance to what we are doing here, as does but to a lesser extent abrading the terminal (which has obvious merit if there is in fact significant resistive oxide on the terminal).

 

[Gazoo]

The negative terminals on all my 8 cells had some type of gunk on them. The positive terminals were fairly clean. I didn't try goo-gone but acetone didn't work. I bought some 600 grit nail files from Amazon and they did the trick, but left a little powder on the terminals and around the cells.
So I wiped the terminals off using a paper towel and acetone and that cleaned them up nicely. After that I vacuumed all the cells. Acetone evaporates very quickly. I am attaching a photo of what one of my terminals looked like before I cleaned it.

 

[noenegdod]

lightly sand with emory paper, that sounds reasonable.

If you are going to, dont hold just the emery in your hand. stick it on a straight, flat sanding block. I still havent decided if I am going to but If I do I am going to use a very high grit paper stuck on a machined block.

 

[fafrd]

If you are going to, dont hold just the emery in your hand. stick it on a straight, flat sanding block. I still havent decided if I am going to but If I do I am going to use a very high grit paper stuck on a machined block.

Good point. Seems very flat know and wouldn’t want to impact that...

 

[fafrd]

The negative terminals on all my 8 cells had some type of gunk on them. The positive terminals were fairly clean. I didn't try goo-gone but acetone didn't work. I bought some 600 grit nail files from Amazon and they did the trick, but left a little powder on the terminals and around the cells.
So I wiped the terminals off using a paper towel and acetone and that cleaned them up nicely. After that I vacuumed all the cells. Acetone evaporates very quickly. I am attaching a photo of what one of my terminals looked like before I cleaned it.

My terminals have similar small scratches & dents to yours but none of that adhesive / gunk. Where did you purchase your cells from?