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What Happened To Duracell PowerCheck?
(hackaday.com)
This is a most excellent place for technology news and articles.
The tongue test works great. Be warned, though, that a full battery will make your tongue go numb. It'll feel like you have a big hole in the middle. Try it.
Ouch, I never had that problem, but I only barely touch it, lol. It's a little shock and slightly numb briefly. But fortunately I never had full numbness that lasted more than a second or two. But I haven't done it in a long time since I have a tester now. ๐