tanstaafl:
What devices have you seen that use batteries in parallel? This isn’t usually done to get higher current, because you can’t rely on most batteries, particularly low-internal-resistance ones to divide larger currents, than one of them is designed for, equally among them. For a current one could handle for its rated lifetime, you might get more in parallel to handle same for a longer time. To get multiple more-or-less voltage-source batteries to increase their common load current you’d have to connect them to separate inputs of some kind of common regulator.
Arjuna34:
When you speak of “adapters that can convert a[n]. . .AA or AAA battery into [a] larger size [battery],” I assume you just mean that these adapters merely reposition the device’s power terminals so as to be able to take higher-current batteries. You certainly don’t mean that these adapters produce more juice out of the small batteries themselves, do you?
Besides different voltage and current requirements of different devices/toys, there’s this thing called ‘form factor’. Small devices/toys may turn out more effective with their power sources crammed into different, possibly odd, shapes.
As an ex-hardware electronics engineer, I see these software geeks program all kinds of things, but I ain’t seen no one give 'em a battery yet they could program (for current, voltage, size and form factor). 
Just 'cause 'lectronics is exploding in complexity and sheer mass, doesn’t mean any of that messy battery chemistry can do the same with ions. That stuff is still a black art. I worked a little while, not too long ago, at company in Berkeley trying to develop a lithium-sulphur battery. I don’t know anything at all about electrochemistry, but they sure didn’t seem to know what they were doing, although they sure seemed to know how to convince investors to let loose of their bucks, at that time Monsanto, the other day the gov’ment. . .now some 10 yr down the pike (definitely not an electronic/software timescale).
For the Y2K meltdown, they showed on the TV news tonight a hand lantern you just crank about 20 revs and it’ll give you approx. 1/2 an hr of flashlight beam. Not sure the kids are into that much cranking. Could return to the old spring-wound toys. . .if you’re not into more dangerous sources of power – say CO2 cartridges.
Is there no relation between the letter designations of electrochemical cells and those associated with the different power inputs to old tube-employing radios? Those radios had ‘A’ inputs to heat the tubes’ filaments (low voltage, high current), ‘B’ inputs (high voltage, moderate current) for high-voltage for their anodes/plates for electron attraction, and negative ‘C’ inputs (moderate voltage, essentially no current) to bias the tubes’ control grids. The 'A’s and 'C’s then would seem to maybe correlate, and the nature of the radio 'B’s would explain their absence in modern life, where small devices no longer need high voltages. In the days of tube radios, in AC-powerless locations, a ‘B’ “battery” was truly a battery of small cells, in series in order to get the high voltage, usually 67 1/2 v minimum.
Ray (My calculator does very well on a solar cell I never have to change, thank you.)
