Guly Do Prado and Lee Barnard scored in either half as Saints boosted their promotion bid, while another season in League One beckons for the Addicks.
Powell said: "We were beaten by a good team who are flying.
"You need to make a good start when you come to a place like this and we did have some little passages of play but they scored 10 minutes in and that is a mountain to climb.
"We did have one or two moments but we were beaten by a better team.
"They`ve got it right with their team and they can go on and play Championship football. If they keep their calm they will make it."
Source: PA
Source: PA