I'm not an electrician. Ebay description says it can produce up to 20W for USB devices you've to set it to 5V, online calculator tells me when entering 20W/h and 5V it's 4000mah, my phone's charge capacity is 3000mah.

Makes me almost think I can fully crank up my phone's charger in about 45 minutes of nonstop full powered cranking, it kinda feels like bullshit. Ebay chinesium fake descriptions and all that.

I asked a similiar question here on /diy about foldable mini solar panels and got some answers. At first I asked on that tech board 4chan has, but they suuuuuuuuuck, you can't discuss actual tech there. Given such crank genereator should have /out uses, few here can give me some insight I hope.