Sunday, February 03, 2008

and in case you were wondering,,,

There are six little 1.5 volt cells inside every 9 volt battery. You can see them here, all connected in series. They are smaller than AAA size, though about the same diameter, only shorter.

Each cell is connected with a metal tab that is spot welded to the end. The case is nothing more than a painted can.

The 9 volt battery was a star of the 1960s, when millions of them powered transistor AM radios for hours on end. This was quite a feat, as only a few years before, portable radios had two batteries, and used current-hogging tubes, so the battery life was short.

These are called "dry cells" but they aren't really dry. If you open them up, which you should not do, you will find they have a pasty electrolyte in them. Sometimes that electrolyte leaks out, gets into the radio, and makes a corroded mess. Nasty stuff, but it usually can be cleaned up.

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