Why Aren't There Any "A" and "B" Batteries?

Old fashion radios that used vacuum tubes (valves in UK) needed a low voltage and a high voltage.

The low voltage battery, used to up a light bulb like element in the tube that emitted electrons, was called the A battery. The high voltage battery, supplied the current that actually made the radio work, was called the B battery. These were not particular batteries, just terms for the low and high voltages.

When they started creating standard size batteries, they avoided A and B so there wouldn't be confusion.

There also used to sometimes be a third battery that supplied needed voltage in some circuits. This was called the C battery, and there is, confusingly enough, a C size, too.

A couple sizes you don't see much of these days is the F cell, which is like an extra long D cell, and the N cell which is a half length AAA.

B Batteries

A B battery is any battery used to provide the plate voltage of a vacuum tube. It is sometimes colloquially referred to as a "dry battery"

In small print, especially, it is harder to distinguish between "A" and "B". To avoid confusion, the current system was developed.

The last freak that went to the store used them all. lol