Enoch Showunmi pounced on a defensive slip to put Tranmere in front midway through the first half, but Miguel Angel Llera marked his return to the side with a 54th-minute equaliser for the Addicks direct from a free-kick.
Charlton had several penalty appeals turned down by referee David Coote and Powell was careful to choose his words carefully.
Powell said: "Referees have a tough job to do. They'll always be under pressure. All you ask of them is to be fair and do the right things.
"They'll get things wrong and right and that's all I can say on it. It's important that we've stopped the rot.
"When you lose games it will eat away at players' confidence, especially at home. We've lost the last two here and everyone was edgy."
Source: PA
Source: PA