The Addicks had to settle for a point after Adam Clayton's late penalty cancelled out Rob Hulse's opener.
It was a spluttering display, particularly after the Terriers were reduced to 10 men when referee Lee Collins controversially red-carded Keith Southern in the first half for a challenge with Michael Morrison.
"We got the breakthrough and had a chance to wrap the game up. It wasn't taken and we had to stand firm. We just couldn't hang on," Powell said.
"We had chances to win it even after that and it wasn't to be. People are frustrated, but have to take positives. It's 10 points from the last 12 and we are in a good place. It keeps our run going."
With his opposite number Simon Grayson furious over the sending off, Powell was sympathetic and added: "It's not a sending off. It's an honest challenge and both didn't pull out.
"He makes a decision and it's 11-10 and it can be tough breaking them down."
And on Arsenal loan signing Emmanuel Frimpong, who impressed during his hour-long debut at The Valley, Powell said: "He was very good for the hour he was on.
"He showed strength, passing ability and we knew we were getting a good player. For a debut, in those conditions, he should be proud."