In regards to batterys - there are AA, AAA, C, D, and 9 volt. What happened to A, CC, DD, and any other volt?

Gnomon

There are lots more than just those. Originally there were A, B, C, D. They wanted a smaller one than A and since there wasn't a letter before A, they got AA. Then they wanted another smaller one so they got AAA. This explains why there are not CC, DD. A and B seem to have died out. The cylindrical ones are technically cells although everyone calls them batteries. They always produce 1.5V because of the chemicals in them. That can't be adjusted. If you want more, you have to string them together. When this is done inside the one case, it is called a battery, so you can get any mutiple of 1.5V. I've never seen 3V or 7.5V but 4.5V batteries are still available and 6V batteries are quite common for torches (flashlights). 9V batteries are very common. Oct 10 02, 7:11 AM

RickF

In the days of valve radios, HT dry batteries in excess of 100V were common, as were 'grid bias' batteries with a variety of tappings for different voltages. Plus, of course, the lead/acid accumulator, charged up weekly at the local cycle shop! Oct 10 02, 9:11 AM