How to protect a battery terminal after removing corrosion?

Question

I have repaired a corroded battery terminal by neutralizing it in vinegar and then cleaning it with a wire brush. The result is a terminal lead which now has bare steel visible where the protective chrome layer has been destroyed.

What kind of treatment can be done to this surface to protect it from oxidation now that the steel is exposed? Even if it doesn't corrode again in the future from a battery, I believe oxidation of the steel can still lead to further damage to the surface and it's electrical conductivity.

I am interested in both inexpensive solutions such as an aerosol spray as well as other more expensive options for an electronics hobbyist that relate to this type of repair.

Answer 1

Any spray is likely to be an insulator, negating the function of a contact.

Most solders, whether pure tin, older (non-RoHS) Pb/Sn, or newer Bi-RoHS types, are more corrosion-resistant than plain steel. Having had the same issue, I sand the actual contact area to remove any oxidation and cover just that area with solder. Making solder adhere to steel or iron is more difficult than to copper, though, and may require acid flux and higher temperature.

BTW, you've already done a good job of surface preparation.

Answer 2

WD40 displaces moisture but allows contacts to penetrate the thin film for a reasonable resistance ~ 100 mOhms, if there is sufficient force.

It will eventually dry out and leave a thin residue so it is not permanent.

If you had liquid Tin, after cleaning off oxide, dip then rinse in water. That is better but you have to buy bulk (2L?) so this is not practical.

Solder works but will oxidize rapidly in humid weather >90% RH.

Answer 3

Dielectric grease is suitable for this appliction.

It protects surfaces from corrosion.
While it is an insulator, when two conductive surfaces are mechanically forced together the grease layer is easily displaced.
In very low contact force situations it may act as an insulator but, even in this application, it is likely to work well.

There are many on web exmples of its use on terminals. One example only here -
WHAT IS DIELECTRIC GREASE AND WHAT IS IT USED FOR?

• " ... dielectric grease is specifically formulated to protect and insulate electric systems. It has many practical uses including automotive tune ups, home electrical work, and recreational vehicle wiring. Because dielectric grease does not dissolve in most liquids, it’s also extremely good for marine and outdoor applications. It can be used to lubricate the rubber parts of electrical connectors, spark plug wires or to protect electrical connections on your boat or recreational vehicle.

• Some of the most common uses include Battery terminals. Spark plug boots, Bulb sockets, Trailer connectors, General electrical connections, General plastic or rubber lubrication ... "

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Other references:

Difference Between Dielectric Grease and Silicone Grease

Dielectric Grease

• "... Dielectric grease is often used for battery terminals to prevent fusing and corrosion as well as high-energy ignition systems to prevent voltage leakage; however, it can also be used in combination with other various terminals and connectors, such as butt connectors, ring, spade, and heat shrink terminals. ... "

Answer 4

You can use technical Vaseline (best solution), or - if you haven't - any grease or machine/engine oil. And don't use any vegetable or animal fat, or vegetable oil - these tends to hardening because of oxidation, or to decomposing, and can cause corrosion.

Answer 5

Use dielectric grease or Battery Terminal Protector made by CRC. Terminal protector sprays on red and will last many months. Eventually, the red disappears indicating it needs to be reapplied. It is meant for car battery terminals.

I would use dielectric grease. It has many uses.