But then how to safely wake a sleeping beauty BMS? Or charge a device when you are in the boonies?
Your USB fan won't do those things. I don't know much about BMS, but maybe a wall wart would wake one up. Amazon ships devices only to the address on my charge card, so why would I want to charge them when I was in the boonies?
In the 70s, I had a friend who was a custodian. He loved long-life incandescent bulbs. They were designed for something like 135 volts. They were advertised for high-vibration environments, where the cooler filament would be less fragile. They were also good for hard-to-change locations and places where a generator might surge well above 120 volts. They were less efficient, requiring more watts for the same light. Considering both power and bulb costs, the standard bulb was usually more economical.
The Centennial bulb runs so cool that it provides little light for the power it consumes. Edison produced a bulb that would last 1200 hours, but the industry later reduced it to 750 for a 100 watt bulb. It meant more bulb sales, but it also helped the consumer because the hotter filament could produce the light you needed for less electricity.
Edison said the problem was not bulb life but switch life because the homeowner couldn't simply screw in a replacement switch. He predicted that the light bulb wouldn't really be a success until somebody invented a better wall switch. It was an immediate hit in commerce and industry because brighter, safer, cheaper artificial light meant they could operate longer hours in winter, but in 1900, after 20 years, only 3% of homes had electricity. The primary motive for these homeowners was probably appliances, not lights.
Compared to a store, a home lit smaller areas at lower intensity. Gas and oil lamps were adequate. Switching on a light would have been more convenient than lighting a lamp with a match, especially coming home to a dark house, when one needed to carry matches in a safe. But it would be terribly inconvenient if the switch didn't work.
Electricity came to this town in 1918. The farmer who built my house saw it as the solution to two problems: the uselessness of his wind-powered well pump on windless days, and the toil of doing launry in a hand-cranked washer. He paid the power company to bring lines to a concrete building he erected in 1920 beside his house to be his pump house and laundry. It still made more sense to light his house with oil lamps.
In fact, the problem had been solved. In 1919, a better switch had been patented. The house was wired in 1926. Inside the front door was a pair of push-button switches, to operate the porch light outside and the chandelier inside. After 99 years, those switches work flawlessly. Unlike the Centennial bulb, they don't waste electricity.
In 1920, 41 years after Edison's light bulb, only 1/3 of American homes had electricity. By 1930, 11 years after the switch was patented, 2/3s were wired and the remaining 1/3 were clamoring for service to be brought to their area.
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BULB 
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