Gen 2 Traction Battery Blue Corrosion

This corrosion on the bus bars on this Gen 2 traction battery are blue, not pale blue and not green. In addition, they only occur on the negative battery terminal.

This battery has been sitting in my garage for a couple of years, and I plan to swap the traction battery in my prius. Before I do install it, I want to clean any corrosion that may cause issues. The battery shows 206 volts without any charging or conditioning. I plan to measure the individual cells to ensure within some tolerance.

Is this copper sulfate corrosion, with the sulphur coming from the atmosphere? I don’t think sulphurs is used in the batteries. Why just in the negative terminals. none of the positive terminals have any visible corrosion!

Can you confirm I need to clean the bus bars and hardware, and also suggest what would be best to clean them with?

 

Interesting, I can find chemical formulas for those two minerals. You must be a “rock hound.”

 

I can see you are a creative out of the box thinker. I don’t have a diesel engine running or any sulfuric acid in my garage. The Prius battery in the car this traction battery came from was a Toyota AGM battery.

i do have other paints and shop chemicals in my garage but nothing near this battery.

I took one of the bus strap nuts loose where bluest, and there was no corrosion underneath the nut.

 

WHY JUST THE NEGATIVE TERMINALS?

 

I found these tidbits that a chemist might use to help me?

From Transformation of Copper: A Sequence of Chemical Reactions.

Hydroxide ion (OH-) binds to the copper (II) ion even more strongly than does water. As a result, hydroxide ion can displace water from the copper (II) ion, yielding copper hydroxide, Cu(OH)2, a blue precipitate. Heating copper hydroxide produces copper oxide, CuO, a black solid.

From
Hydrogen: What’s the difference between H, H2, H+, H- and OH- ? - Watermatters.

Hydride is a hydrogen atom which has an extra electron. This means that it is a negatively charged ion, or anion. That is why Hydride ion (H-) has the minus sign distinguishing it from a regular Hydrogen atom (H). The two dots after the H means that this ion has two electrons instead of just one. The extra electron means that H- is not a free radical however it is not stable because this form of hydrogen is a very strong base (extremely alkaline) which reacts with water to produce hydroxide (OH–and molecular hydrogen (H2).

H:– + H2O –> H2O + OH–

Hydride (H:– ) also reacts with metals to form chemical compounds which are reducing agents

From Nickel–metal hydride battery - Wikipedia.

NiMH cells have an alkaline electrolyte, usually potassium hydroxide. The positive electrode is nickel hydroxide, and the negative electrode is hydrogen in the form of an interstitial metal hydride.[20]

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So some hydride is escaping from the negative terminal and combining with the copper to make copper hydroxide???

And I should be able to clean it with maybe a weak acid?? What do you suggest????