Galvanic Corrosion

[NinjaDeathMonk]

Hi, everyone. How significant is galvanic corrosion in a portable DIY system? Like when soldering an aluminum wire to a copper XT60 terminal. Or soldering a copper wire to a circuit board. Or just soldering or crimping copper and aluminum wires together. Thanks.

 

[svetz]

Really great question! Can't wait to see the responses... definitely bookmarking this thread!

Although I suspect the folks on boats will have different responses from those living in the desert. Conformal coatings might make a difference too.

 

[wntstr]

Galvanic corrosion is a real problem in electrical connections exposed to the elements. On high current carrying connections, it's effect on system performance is not significant, but the effect on overall life, reliability, etc can't be ignored.

Galavanic corrosion in sensing connections (Kelvin terminals on shunts, for example) can cause very large measurement errors. due to electro-chemical potentials induced in the contacts. In addition, the use of dissimilar metals can cause spurious voltages in the contacts due to the Seebeck effect.

 

[gnubie]

A little bit of moisture is all it takes and everything goes to hell when you have different metals unless they are well matched. Take a look at how quickly your telephone line is stripped of copper, and that's around 48V idle. Aluminium will suffer a quick death when in contact with copper in the presence of a little water.

Why are you using aluminium wire?

 

[NinjaDeathMonk]

Galvanic corrosion is a real problem in electrical connections exposed to the elements.

So exposure is the key? If the connection is protected, then the problem is lessened?

Why are you using aluminium wire?

I'm basing a portable DIY solar system on a uninterrupted power supply (UPS), which already has aluminum wires in it. I was thinking of upgrading the wires to copper, but I may be causing more problems than helping. Additionally, I'm using XT60 connectors with copper terminals, an AiLi Battery Monitor that has a copper shunt, and standard 120v outlets that have copper terminals too.

 

[svetz]

From Wikipedia"

Galvanic corrosion (also called bimetallic corrosion) is an electrochemical process in which one metal corrodes preferentially when it is in electrical contact with another, in the presence of an electrolyte.

That's why I was wondering if a conformal coating would help.

 

[gnubie]

I'm basing a portable DIY solar system on a uninterrupted power supply (UPS), which already has aluminum wires in it. I was thinking of upgrading the wires to copper, but I may be causing more problems than helping. Additionally, I'm using XT60 connectors with copper terminals, an AiLi Battery Monitor that has a copper shunt, and standard 120v outlets that have copper terminals too.

OK. I'm guessing the UPS itself isn't exposed to the elements so if the copper / aluminium joint is inside the UPS it's not going to be a problem. Seal the joint up if it worries you.

 

[wntstr]

So exposure is the key? If the connection is protected, then the problem is lessened?

Yes. If these are crimped connections, cover with exterior grade UV stable caulking compound or any other suitable potting compound. For connections in sensing wires, use silicone spray or other moisture repellent products designed for electrical contacts.

 

[Rider]

I use Plasti-Dip spray.

 

[Supervstech]

Hi, everyone. How significant is galvanic corrosion in a portable DIY system? Like when soldering an aluminum wire to a copper XT60 terminal. Or soldering a copper wire to a circuit board. Or just soldering or crimping copper and aluminum wires together. Thanks.

I don’t think you can solder aluminum to copper connections... good coatings, and quality crimped connectors, sealed with moisture lock shrink wrap should be the best I think...

hmmm... maybe copper clad aluminum can be soldered. But... I still think crimp sealed is he best.

 

[gnubie]

Hit it with some alusol to wet the aluminium then good old 60/40 on the copper and it should take. Crimp is always a good idea when dealing with a lot of current.

 

[bulrush]

I'm guessing this will be more of a problem at times of high humidity, like any Michigan summers. The humidity will increase the corrosion (chemical reaction). Michigan seasons are so humid that my table saw in the garage locked up from rust. Since I don't have a basement I will not replace the saw.

 

[b.james]

Boaties use a cream like zinc cream , the purpose of which is to pass current whilst filling the miniscule gaps between the items joined . This stops water from getting in between the pieces and forming a battery which corrodes out one of the metals.

Often used betweeen alloy and stainless is tef-gel and the like.
Dielectric Grease is also used.

I used to grease all my battery terminals after hitting them with boiling water to dissolve away the lead acid corrosion.
I tried lanolin grease on my battery terminals years ago and it stopped current flowing through the teminals so make sure you get the right one for your needs.

Grease and Petroleum jelly work, but I now use copper based grease directly on the terminals and although the corrosion factor is gone with LFP batteries, galling and seizing and the dissimilar metal effects of connector bolts terminals and straps and washers will still happen so I still use a little copper based grease on my connections.

 

[RandyP]

Noalox compound, a standard in the electrical utility industry for Cu/Al terminations ?

iDEAL Noalox Anti-Oxidant Compound 4 oz. 30-026 - The Home Depot

Use the IDEAL NOALOX 4 oz. Anti-Oxidant Compound to improve the efficiency of aluminum conductor connections. This compound provides additional inner-strand and inner-conductor current paths. For use with pressure type wire connectors including screw-on, tap, service entrance and split-bolts.

www.homedepot.com

 

[NinjaDeathMonk]

Noalox compound, a standard in the electrical utility industry for Cu/Al terminations

That seems fantastic. Thank you.

 

[tb-av]

There are many aluminum to copper connectors available. How hard would it be to get rid of your aluminum? I don;t understand why the aluminum wire inside your inverter would be connecting to copper outside. But maybe I am misunderstanding.

If you are using something as small as an XT60... you might as well put the Al/Cu connector in between.

I've never seen a circuit board that wasn't copper... so soldering copper to a circuit board is a non-issue.

 

[b.james]

Usually they have alloy terminals on the battery. Copper and aluminium are very close on the conductivity scale.

 

[tb-av]

You know, I'm going out on a limb here. Since we are all new. To the OP, is it possible you are seeing "silver wire" or "silver solder pads" and assuming they are aluminum?

In most modern devices those two would be 'tinned copper" IOW, copper pre-treated with solder. A good example is Ancor Marine wire. It's silvr in color but it's copper wire that has been 'tinned' . Or a circuit board that has silver pads.... same thing.

I didn't realize any modern gear had aluminum wire in it.

 

[b.james]

Alloy is easier to machine and the pouches are bolted to it inside the pack . See if you can grab a look at a dropin and you will see it immediately. anyway looking at what others read into the OP .

 

[NinjaDeathMonk]

You know, I'm going out on a limb here. Since we are all new. To the OP, is it possible you are seeing "silver wire" or "silver solder pads" and assuming they are aluminum?

? Well, that's embarrassing. Yeah, that... that pretty much explains everything.