Says it needs 72 hours of constant light to fully charge. Do you just put it under a light bulb for 72 hours or what?

Hello Yota, There must be a misprint as it should be only 24 hours of light. If you put the cap in place, over a day or two of time it will gather more than enough sunlight - provided that we are not in the depths of winter and overcast skies-to begin to power itself, most-likely before the full 24 hours. Thank you for your inquiry. Your Deckorators Team