Liam Sercombe, John O'Flynn and Ryan Harley, from the penalty spot, netted second-half goals to dent the Addicks` promotion bid.
Bradley Wright-Phillips then netted a fourth goal in five games for his new club but it was too little, too late for Powell`s side.
"I felt we were on the front foot for long periods," said Powell. "Nathan Eccleston had a chance in the first half which produced a fantastic block by their defender. That sort of defending for an away team on a big day like this can crush you but we kept going and that has admiration from me.
"I had to put in a young player, Carl Jenkinson at right-back, who I felt did ever so well. That is a plus point, if you can have one on a day when you lose a game.
"But I'm still pleased with the fact we created chances. It is just about taking them and having that composure when you are in the final third. I'm pleased in that respect because I think it was about 12 chances we had. It was a tough day for everyone because really you are looking at it and you would like to take those chances."
Source: PA
Source: PA