Johnnie Jackson had fired the Addicks ahead at The Valley, only for Reda Johnson (84) and Leroy Lita (89) to earn the Owls a surprise three points in south London.
The result was a shock to play-off contenders Charlton and Powell admitted: "That's football, sometimes you love the game and sometimes you hate it.
"It's one of those days that hasn't gone for us. The turning point was when we hit a post (a Scott Wagstaff effort), that would have sealed the deal for us.
"It's a tough way to lose after playing our part in a tough game. We got stronger and better as the game went on and went ahead through a good goal, but then couldn't see the game out
"It's a bitter pill to swallow but the players have done terrifically well this past month."