As someone who had a similar experience several years ago, don't forget that, if you leave the room and remove the key, you won't be charging things either (if you leave something plugged in, hoping it will charge while you're out). I solved that by leaving the second key in the slot when I went out (and yes, making sure all of the lights were turned off...I'm not a monster).
RE: Just sat in the dark for 10 minutes