The Addicks were among the pre-season favourites for promotion but Tuesday night's 2-0 defeat at Rochdale left them in the bottom half of the table and 12 points adrift of Bournemouth in sixth.
"We've been paying for not defending correctly and not taking the half-chances that come our way," admitted Powell.
"It's tough for us but but I've told the lads to keep believing, they will go in. I've got to look at it now and make sure we have an eight-game season.
"We have to finish on a high, and on a good note."
Source: PA
Source: PA