I’m only half kidding. I’m a bit of a prepper and I have lots of powerbanks and devices that charge from USB but besides idling my truck I really had no other way to charge any of them in case of a long-term power outage which seemed a bit of an oversight on my part.
Not like this solves the issue. 30 watts (under ideal conditions) isn’t much but it’s a start.
It doesn’t. It takes longer to charge to 100, but the efficiency is basically the same. The amp draw drops after 80%. If you are using a engine to charge, you would lose efficiency because of the extra time, but using solar wouldn’t have this issue.