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?
It's been my suspicion for a while that the greenish stuff is chemically malachite and that the deep-blue stuff is azurite. I'm pretty much unqualified to suspect anything in that department, but the color seems kinda right. The formula doesn't seem to involve any sulfur: Azurite: Mineral information, data and localities.
Copper sulfate is also blue, although usually a little lighter than the blue in the OP's picture. There might be sulfur in the atmosphere in that garage if it contains chemicals which release sulfur compounds. Does the OP happen to have a vat of sulfuric acid sitting in the corner of the garage, or a diesel truck or generator running inside on high sulfur fuel? Hmm, is the 12V in this car the right type? If it has been replaced with a typical car battery that might be an issue.
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.
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] ____ 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????
Boric acid solutions are mentioned in the Toyota manuals for neutralizing spilled NiMH electrolyte....
I cleaned mine on a wire wheel, then final polish on fine grade wet & dry sandpaper using kero as the lubricant/washing agent. Dried them off and coated them with Alminox, but any electrical paste designed to protect copper in a mixed metal contact area where current passes through will do the job. The seal around the negative terminal is leaking, probably due to high internal pressure caused by the pressure relief valve being stuck in each module. They are designed to release at 80psi, but on the module reconditioning thread, a member tested their aged module and found it required more than 125psi to get the valve to release, but it returned to the 80psi once it was dislodge. T1 Terry
