Powell took exception to one of a number of meaty challenges in a fiery London derby against Leyton Orient, which finished 1-1 after extra time.
Johnnie Jackson and Lawrie Wilson then missed Charlton's first two penalties as Orient pulled off a shock against the Championship new boys.
Charlton took the lead after 28 minutes from a swift counter-attack led by new signing Jordan Cook.
The former Sunderland youngster's superb through-ball found Scott Wagstaff whose early, angled drive took a deflection off Gary Sawyer to leave Orient keeper Ryan Allsop with no chance.
But Orient levelled in first-half stoppage time when Sawyer's corner was flicked on by Scott Cuthbert and O's debutant Mathieu Baudry nodded the ball home.
Orient should have taken the lead five minutes into the second half when Charlton new boy Wilson clipped David Mooney in the area.
Former Addicks striker Mooney picked himself up to take the penalty but crashed his effort against the crossbar.
Referee Gavin Ward then banished Powell from the touchline before home winger Danny Green thumped a drive against the post.
Extra time could not separate the sides and Allsop saved from Jackson before Wilson hit the bar and Stoke loanee Ryan Brunt fired Orient into round two.