During the period of the pre-transistor era, (45's-60's), portable vacuum tube radio receivers were produced requiring the use of 2 or 3 separate batteries. One of these batteries, the "a" battery, powered the filaments of the radio tubes. The other, called the "b" battery, powered the anode (plate) and cathode circuitry.
The radio doesn't play because the a batteries are dead but the b batteries are fully charged.
AA, AAA, C, D, 9v are some common battery types, but there are no B type batteries. Maybe to avoid confusion with a stutter. pronounced BEBATTERIES (one word).
Made popular by comedian Demitri Martin
Do you have any B Batteries?