Hi, hey it turns out that “B” batteries were quite the thing at one time, actually for quite some time. They were used to provide plate voltage for portable tube-type equipment until transistors came along. Common types of “B” batteries provided 22.5, 45, 67.5, and 90 volts, and were commonly used in hearing aids, portable radios, portable amplifiers, phonographs, and other ancient tube-type stuff. One other interesting feature of this equipment is that aside from battery power, it will usually run on 110 ac or dc. By the by, the “A” batteries were used to power the filaments for the tubes. Have a good one, Bill.
The column in question is “How come you never see any B batteries?”, at http://www.straightdope.com/classics/a4_005b.html
It the early days of radio, with three-element vacuum tubes, you used up to three batteries to control the currents to each of the elements. According to my copy of “Letters of a Radio-engineer to his Son” (Mills, 1922), the A battery was connected to the filament, the B-battery to the plate, and the C-battery to the grid.
At this time, car batteries were commonly used as the B batteries, but I don’t think there was any standard voltage or design for these A, B and C batteries. And I don’t think these B batteries have anything to do with the later standards sizes that Cecil’s column talks about–it was just a way to keep track of the three batteries used in the radio set.