Boneflour inspired me to go looking for some things. Now I share my bounty with the people.
People who are already into DIY will have heard of this: https://www.pbs.org/newshour/science/isolation-generation-master-inventors-cuba. I wasn’t able to track down an English translation of Con Nuestros Propios Esfuerzos, but there are likely better pamphlets in the prepper community waiting to be found. Nothing against Cubans, but I hear this pamphlet is as much about foraging edible Cuban plants as anything else, and as a rule I prefer to seek out the writing/illustration of American plainstyle writers. I share the story because it’s as much an attitude of mind as anything.
Here’s a great introduction to the theory of electric motors. A generator is the same thing except backwards: you rotate the shaft somehow (e.g. a water wheel) and push current into a chargeable battery. https://odysee.com/@PublicSource:c/How-does-an-Electric-Motor-work–(DC-Motor):0
In general you can find a lot of good “how does X work” videos on Odysee easily because it’s not yet full of nonwhites, women, and other types of reputation hacker. (The secret ingredient to compelling creative content is genuine love.)
Here’s a starter project I want to try building next year after I’ve graduated. http://www.five-gallon-bucket-hydroelectric.org/wp-content/uploads/2013/11/FIve-Gallon-Bucket-Hydroelectric-Generator-Build-Manual-.pdf