Marvin Sordell swept Charlton back in front after the break with his first goal for the club since joining on loan from Bolton.
Powell said: "It was a real heart-warming performance and all that it lacked was the goals. We need to be more clinical and take chances when they come.
"We could have been two or three up by half-time and at 2-1 we were pegged back by a deflected goal.
"It was a good cup tie that ebbed and flowed but the performance gives me a lot of pleasure and there is a lot to look forward to."
The Addicks have only won once so far this season - against Oxford in the League Cup - and Powell added: "We're going through a tough period.
"We just need something to pick us up. We couldn't see the game out but there are plenty of positives to take us forward."
- Sports & Recreation