Avoiding Galvanic Corrosion

[Opie91]

I believe you have tinned coper busbars. They are tinned to prevent corrosion. So no, no need to replace for copper ones IMO.

+1

 

[Hedges]

At 27 amps, I doubt the IR drop through busbars affects voltage reaching motor, so doubling up shouldn't be detectable.
Maybe you made better contact on the second try.
Any way you can apply a load and check temperature of each busbar?
There was one guy with poor contact and some hot busbars. Once he cleaned oxide and applied a compound, the problem was fixed.
Aluminum has a native oxide, and clamping two flat pieces together won't get through it.

 

[Haugen]

Thanks. I was beginning to think it would all fall apart by the end of the year or something.
I use to make model railroad electronics etc and never had a problem with galvanic anything back then. I am sure it would happen in time but even so. Not weeks or months.

Ok so I have aluminum terminals, aluminum bolts and I just checked and the cross bar are also aluminum that they sent to me.
Even the connections FROM the batteries are aluminum with copper wire for the mobility scooter.

So I am guessing I am fine for now and should not replace the bus bars for copper ones then eh?
Leave well enough alone?
I will only be pulling 27 amps max and then only for a short while [like going up a hill for a few minutes].

Anyhow, thanks for all of the help here guys.

You are correct. Corrosion is a slow process. That is why prevention is so important.
I have frequently said on here that the most important place to prevent corrosion is on the aluminum threads in the terminals. Everyone seems so stressed out that they are not strong enough, but perfectly willing to install a cathodic steel bolt that could promote the degradation of those threads.
I think you are wise to go with the aluminum bolts. Just be careful not to overtorque them.
Edit: if you don't want to have to do terminal maintenance as @Opie91 detailed on your maintenance free cells, do the prevention.

 

[Gazoo]

There was one guy with poor contact and some hot busbars. Once he cleaned oxide and applied a compound, the problem was fixed.

On my cells, on the negative terminals there is tape residue. Hardly any on the positives. I am going to attach a photo that clearly shows it. I didn't notice it until I had looked at it with a flashlight. I will have to clean them up and will do some light sanding on all of the terminals. A clean terminal will be a happy terminal.

 

[Opie91]

You are correct. Corrosion is a slow process. That is why prevention is so important.
I have frequently said on here that the most important place to prevent corrosion is on the aluminum threads in the terminals. Everyone seems so stressed out that they are not strong enough, but perfectly willing to install a cathodic steel bolt that could promote the degradation of those threads.
I think you are wise to go with the aluminum bolts. Just be careful not to overtorque them.
Edit: if you don't want to have to do terminal maintenance as @Opie91 detailed on your maintenance free cells, do the prevention.

If you want to buy aluminum everything than that is fine, it is just unnecessary. This whole galvanic corrosion thread is WAY overdone. The problem with a 7 page thread about galvanic corrosion is that it discourages people from building packs because they start to think "Geez another thing to worry about" or "I need a PHD to make these things work". It is just nonsense. In addition they spend money that is just plain not necessary.

You don't need a $100 jar of miracle juice or super special aluminum bolts/nuts. Clean everything up, torque it down right and maintain it. Even if you use all aluminum, every connection should be periodically inspected and that goes for any type of battery system.

 

[Deleted member 9967]

If you want to buy aluminum everything than that is fine, it is just unnecessary. This whole galvanic corrosion thread is WAY overdone. The problem with a 7 page thread about galvanic corrosion is that it discourages people from building packs because they start to think "Geez another thing to worry about" or "I need a PHD to make these things work". It is just nonsense. In addition they spend money that is just plain not necessary.

You don't need a $100 jar of miracle juice or super special aluminum bolts/nuts. Clean everything up, torque it down right and maintain it. Even if you use all aluminum, every connection should be periodically inspected and that goes for any type of battery system.

Thank. I think we needed this.

 

[Haugen]

If you want to buy aluminum everything than that is fine, it is just unnecessary. This whole galvanic corrosion thread is WAY overdone. The problem with a 7 page thread about galvanic corrosion is that it discourages people from building packs because they start to think "Geez another thing to worry about" or "I need a PHD to make these things work". It is just nonsense. In addition they spend money that is just plain not necessary.

You don't need a $100 jar of miracle juice or super special aluminum bolts/nuts. Clean everything up, torque it down right and maintain it. Even if you use all aluminum, every connection should be periodically inspected and that goes for any type of battery system.

I talk about the Cadillac of connector lubricants because that is what I have done extensive research on. I regularly discourage people from spending that kind of money on it.
The fact is that the light coat of oil provides a self healing barrier against moisture and oxygen reaching the metal. It's a chemical reaction with a triangle, just like fire. (no PhD required! ?)
There are a lot of options out there for someone who can copy and paste the words "connector lubricant" into a search engine. Most are less than $20. Add $20 in hardware for aluminum bolts and aluminum bus bars, and you preserve practically all of the maintenance free aspects of the lithium batteries.

As I have mentioned, low humidity environments are not common in this world, so it is important to protect your investment by taking a couple simple steps to prevent corrosion over the long life of these cells.

 

[Deleted member 9967]

Just found out they can't sell Noalox where I live in Vancouver.
Not safe or something.
Dang.

 

[Opie91]

Just found out they can't sell Noalox where I live in Vancouver.
Not safe or something.
Dang

Check this out, available in Vancouver: OxGuard

 

[Deleted member 9967]

Check this out, available in Vancouver: OxGuard

Wow, a guard against ox's. So cool. ?

Thank you very much actually.
I have to go to home depot soon anyhow, so I will be sure to get some of this when I am there.

 

[aaron_c]

There was one guy with poor contact and some hot busbars. Once he cleaned oxide and applied a compound, the problem was fixed.
Aluminum has a native oxide, and clamping two flat pieces together won't get through it.

Thanks for posting this, that's my situation--well, the part about using two smaller busbars per terminal is--and I hadn't realized I had to clean off the tin oxide on the side where I smoosh the two busbars together.

Would I be ok using a metal file to get this off? Or would that leave the surface too uneven for good contact?

And I assume I'd need to put some ox-gard between the two plates, right?

I know these are probably really basic questions but I've never done this before and it would be nice to get it right

 

[Deleted member 9967]

Thanks for posting this, that's my situation--well, the part about using two smaller busbars per terminal is--and I hadn't realized I had to clean off the tin oxide on the side where I smoosh the two busbars together.

Would I be ok using a metal file to get this off? Or would that leave the surface too uneven for good contact?

And I assume I'd need to put some ox-gard between the two plates, right?

I know these are probably really basic questions but I've never done this before and it would be nice to get it right

I use ox guard but so far I have not noticed a difference.

 

[cinergi]

Thanks for posting this, that's my situation--well, the part about using two smaller busbars per terminal is--and I hadn't realized I had to clean off the tin oxide on the side where I smoosh the two busbars together.

Would I be ok using a metal file to get this off? Or would that leave the surface too uneven for good contact?

And I assume I'd need to put some ox-gard between the two plates, right?

I know these are probably really basic questions but I've never done this before and it would be nice to get it right

A metal file is too coarse. You need ~3,000 grit sandpaper or the like. Just a couple of swipes followed with wiping down and a de-oxidizer will get you amazing results. ox-guard after the fact but only between dissimilar metals (cell terminal and bus bar). A tinned bus bar shouldn't need ox-guard at all. Just be careful not to remove the tinning - it's extremely thin and very easy to expose bare copper. If you do, you'll need ox-guard between the bus bar and the cell terminal (but not between the bus bars).

 

[Deleted member 9967]

A metal file is too coarse. You need ~3,000 grit sandpaper or the like. Just a couple of swipes followed with wiping down and a de-oxidizer will get you amazing results. ox-guard after the fact but only between dissimilar metals (cell terminal and bus bar). A tinned bus bar shouldn't need ox-guard at all. Just be careful not to remove the tinning - it's extremely thin and very easy to expose bare copper. If you do, you'll need ox-guard between the bus bar and the cell terminal (but not between the bus bars).

Aha, ok that is good to know.
Thanks

 

[aaron_c]

A metal file is too coarse. You need ~3,000 grit sandpaper or the like. Just a couple of swipes followed with wiping down and a de-oxidizer will get you amazing results. ox-guard after the fact but only between dissimilar metals (cell terminal and bus bar). A tinned bus bar shouldn't need ox-guard at all. Just be careful not to remove the tinning - it's extremely thin and very easy to expose bare copper. If you do, you'll need ox-guard between the bus bar and the cell terminal (but not between the bus bars).

Oh...so I'm removing the oxidized layer of tin but not the tin itself? Did I understand that correctly? Or are you saying I should be careful not to remove the oxidized layer on the outside of the new bussbar sandwich?

 

[Hedges]

I wouldn't worry about oxide on tin unless you unearthed some tin-plate copper that had been buried underground.
It is the native oxide on aluminum you need to remove.

 

[cinergi]

Yup. I still give it a gentle scrub to remove any junk that got on it.. tape residue, dirt, oils (which is why I follow up with de-ox), etc.

 

[aaron_c]

Yup. I still give it a gentle scrub to remove any junk that got on it.. tape residue, dirt, oils (which is why I follow up with de-ox), etc.

De-ox is to remove oxidation from the soapy water? I'm having trouble finding some, actually. I searched for it in amazon and didn't come up with anything helpful... I did google "how to remove oxidation from copper and came up with a wikihowto article that suggested using a mixture of baking soda and white vinegar. Is that going to work?

Sorry for these basic questions, this is all so new to me

 

[Bob B]

De-ox is to remove oxidation from the soapy water? I'm having trouble finding some, actually. I searched for it in amazon and didn't come up with anything helpful... I did google "how to remove oxidation from copper and came up with a wikihowto article that suggested using a mixture of baking soda and white vinegar. Is that going to work?

Sorry for these basic questions, this is all so new to me

On Amazon, try searching for Noalox or just no-ox .... there are others like ox-guard. The Noalox is designed specifically when there is contact with aluminum.
I did see De-Ox on Ebay.

 

[aaron_c]

On Amazon, try searching for Noalox or just no-ox .... there are others like ox-guard. The Noalox is designed specifically when there is contact with aluminum.
I did see De-Ox on Ebay.

Oh, now I'm confused. I thought that stuff like noalox and Ox Gard were a coating you put on to prevent oxidation. Whereas I thought maybe Cinergi was talking about something different, something that would remove oxidation? But maybe I was wrong.