The early Zenith Transoceanic, often shown in old movies sitting over the fireplace in Alaska, was one radio that used filament cathode circuitry for minimal power consumption.
People living in the boonies would drag in several battery packs before being snow bound, and could listen to the short wave news every day for a very long time.
Or you could run them off 115 if you had it.
The newer transistor Transoceanic of course used transistors. I had one of them, and when I retired gave it to my SIL. I think it cost me maybe $270 in 1968.
They were high quality radios for their time. Now I have a small Grundig.
@irlandes: I have one of the early Transoceanics. I have never tried it on battery (if you can even find a B battery these days), and it’s to the point that it needs to be re-capped, but what a great little radio. If you think smartphone battery life is lousy, I’ll bet one of these is much worse.
Kind of off topic, but I hope it’s tolerated:
Most vacuum tubes need at least ~50V on the plate (anode).
There was a series of space charge tubes for portable use that could operate with 12V anode voltage.
Along with tube radios and being OT a bit I might add that in the late 1940s many Harleys used by police departments started running a Motorola receiver and transmitter radio setup. The receiver was in a box on one side of the rear wheel and the transmitter was in a box on the other side; all powered by a dynamo. Those things weighed a ton.
Those bikes are also 6 volts and the RPMs had to be run up to about 2000 to create enough juice to operate the radio and which then pitted the speaker and microphone against the muffler. So a cop would have to rev and raise their voice.
Imagine operating a throttle and possibly a sidearm with the right hand, while shifting gears with the left hand, with the left and right feet on the clutch and brake pedals respectively, and throwing radio operation and mike into the mix all while having to control the handlebars here and there and maintain balance.