Manager Alan Pardew has said he is keen to turn Powell's loan move into a permanent deal.
"I would like him to stay. He is Alan Curbishley's player and I would like to thank him and Charlton for letting us have him.
"But I don't know how much he is going to feature for them this year and I think Chris wants to play - so I think there is a chance we could get him," Pardew told the Hammers official website.