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Archive for October 18th, 2009

More Alkaline Cell Corrosion

Must be something going around…

Corroded clock-thermometer cell

Corroded clock-thermometer cell

The outdoor thermometer over my desk (which also displays UTC so I don’t have to reset the mumble clock twice a year) started blinking. That’s the usual sign of a dead battery and, yup, when I opened it up, that “leakproof” Eveready was pretty far gone.

Surprisingly, at least to me, the cell hovered around 1.1 V open-circuit and 800 mV under the meter’s “battery test” load. Given the amount of corrosion, I thought it would be flat dead.

The corrosion had crawled out of the compartment along the negative terminal and coated the entire metal tab with bluish-green crystals. Some protracted dabbing with vinegar, rinsing with wet cotton swabs, and drying put things pretty much back in order.

I usually scrawl the date on each cell when I install it, but either I didn’t do that here or the corrosion ate the ink. All I know is that it’s been up there for quite a few years; look at the discoloration where it faces the sun through the window!

The thing was a surplus freebie to begin with and has long since been fully depreciated…

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