Road.cc had
an article on the conclusion of his trip as well, with a link to an
article of theirs from before he started. It says he carried one spare battery and planned on ~100 miles per day. I'd still love to know the details of how he handled charging and such (did he charge every day, every other day, how often was he riding with the motor shut down, what assist did he usually run, etc). Some pics have him camping but the article notes he travels light and doesn't list camping gear, so maybe he camped sometimes and stayed in motels and such other times?
Super cool though, and its neat that Yamaha supported him. Some people have been dismissive of their ebike efforts but from what I see, the company is enthusiastically supportive of ebikes and their model line. 20,000 miles is a hell of a trip for an ebike!