alt Hacker NewsThis is amazing to see. I have some audio recordings, digitized from tapes recorded in the 1960s, of my great-grandfather who was raised on a farm in Iowa. He talks about his experiences in amateur radio in the early 1900s-1920s. He mentioned bringing telephones out into the field that could be clipped to the fence wire to make calls back to the house, which was not hooked up to an electric grid but had batteries. Sadly, he did not say how the batteries were re-charged.
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The phone batteries weren't a high load kind of affair. They merely needed to change the varying resistance of the carbon microphone into an audio voltage - on the order of milliwatts of power - to send down the line. A more modern phone, still using a carbon microphone but powered by the line, needed about 20mA of loop current to do this. The telephone terms for the old system vs. the newer is "local" vs. "common" battery.
Heavy duty batteries - specifically the "A" batteries that powered the vacuum tube heaters in early radios - were made rechargeable to save cost.
The batteries were either charged using a "telephone magneto", or were taken to a local town to be charged off of mains electricity:
> Sadly, he did not say how the batteries were re-charged.
Dry-cell batteries had to be changed, they weren't recharged.
https://www.reddit.com/r/diyelectronics/comments/y7qmhq/15v_...
If the batteries were rechargeable at all (some radio 'A' batteries [0] were), they could have been recharged by a small wind turbine [1].
Maybe they used a Delco-Light Plant
My grandmother from rural Saskatchewan said that back then they would exchange their radio batteries when they went to town.
Her husband, my grandfather, lived in Regina but worked on a traveling threshing crew and mentioned seeing a windmill driving an old generator from a car to charge batteries at one stop.