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I have a battery cover that is supposed to make contact between two batteries. Some batteries were left in too long and now there is corrosion on the metal flange.

The corrosion is beyond repair (IE: I cannot file it down to new metal). What can I do to make contact again? I thought of using tinfoil, but that will eventually tear. I also thought of using a whole pile of solder, but I'm not sure how effective that will be.

What is the best way to re-connect the batteries when the cover is corroded? I don't think I can get a new cover from the manufacturer.

Sorry for the delay, here's the image corroded battery cover

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    \$\begingroup\$ Either the contact is still there, in which case some unoxidized metal must still be there, or it's all crumbled and gone. It doesn't make sense that it's there but can't be filed down to bare metal. If there were no metal, it would just crumble. Keep filing or sanding. \$\endgroup\$ Jan 1, 2012 at 0:59
  • \$\begingroup\$ You can't disassemble the device? If you can, you might be able to replace the contact. Photo or some representation of the thing you're fixing would help, as others have said. \$\endgroup\$
    – Rab
    Jan 1, 2012 at 7:44

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Can you post a photo of the rest of the battery compartment? Judging by the photo it looks like this piece connects the positive end of one AA cell with the negative end of another. So all you need is a little piece of metal with a bump on it, that can replace or overlay the original one.

There are a lot of places you can get a patch of metal thick enough to do the job. If the hardware store doesn't have sheet aluminum you can check the hobby store. Even simpler is to cut the ends off a soda can, flatten out the rest, and sand off the ink with wet/dry sandpaper. It's soft enough you can put a dimple in the right place with a phillips screwdriver or chopstick and cut it to shape with heavy scissors. If it's not thick enough you can double or triple it over.

The original metal piece is probably held in place by that hole in the middle, where a bump in the plastic was melted a little, flattened, and allowed to cool to shape. To get it out you might have to whittle that plastic away from the metal, or soften it with a soldering iron (being careful not to distort the rest of the piece).

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Olin is correct - but it can be hard in practice and may result in destruction of what is left.

Ideas only:

  • Shim brass may work well for you - brass sheet is available in thickness of a few thousands of an inch up. Wrapping a sleeve or "U" of suitably thin brass over the dead contact metal should work.

  • You can get aluminum foil that is much solider than what is sold for food wrap. And, failing in in time and needing replacing seems preferable to the alternative.

  • You can buy conductive epoxies, which are often just "ordinary" epoxy loaded with a conductive material - perhaps copper, perhaps carbon black. You can probably make your own by experimenting. Copper filings and epoxy a good starting point. My experience with similar (lacquer loaded with silver for flexible PC track repair, is that you can get connections which do not work but they improve as the epoxy sets. You need pressure on the grains to make a contact to conduct.

  • Ask your local industrial chemical suppliers about "Wood's metal". This melts at about 70oC so can be melted with hot water then poured onto the contact area. I have no experience with this - it may or may not work in this application.

    • Wood's metal is useful as a low-melting solder, low-temperature casting metal, ...

    Other uses include making custom-shaped apertures and blocks (for example, electron-beam cutouts and lung blocks) for medical radiation treatment, and making metal inlays in wood.

    Wood's metal is also useful for repairing antiques. For example, a bent piece of sheet metal may be repaired by casting a Wood's metal die. The low melting temperature of Wood's metal makes it unlikely this will harm the original. The damaged piece can then be clamped in the die and slowly tightened to form it back into shape.

Wood's metal has long been used by model railroad enthusiasts to add weight to locomotives, increasing traction, and the number of cars that can be pulled.


  • Wood's metal is also used in the making of extracellular electrode for the electro-physiological recording of neural activity.2

  • Also - unlikely to be a major issue here, but: : Wood's metal is toxic because it contains lead and cadmium, and therefore contact with the bare skin is thought to be harmful, especially in the molten state. Vapor from cadmium-containing alloys is also known to pose a danger to humans
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