An early goal from Danny Haynes, who later limped off injured, put them in front but Jamie Ward levelled for Derby from the spot midway through the second-half.
The penalty incident also saw the Addicks down to 10 men, with Michael Morrison sent off when he was shown a second yellow card for a foul on Richard Keogh in the box.
Charlton were able to hold on in the closing stages and end a run of three successive defeats but they are still looking for their first Championship win since the end of November.
"We needed that, especially after going down to 10 men. I'm happier than Boxing Day - there were a couple of turning points," Powell said.
"With Morrison getting sent off the players showed a lot of resilience. We've a lot to build on. They were testing conditions, and we dug in to get a point and we move on.
"It was a great strike by Danny, he's been a real livewire. He's got tremendous pace and scored some goals for us - it was a superb goal that lifted everyone."