City got the point they needed to secure Premier League football next season, but the in-form Addicks came very close to spoiling the party.
Cardiff's David Marshall was the busier of the two goalkeepers, pushing Johnnie Jackson's first-half free-kick onto the post before pulling off a stunning stop to deny Ricardo Fuller his second goal in four days.
"We had good spells," said Powell. "I said to the players we had our moments, we definitely played our part.
"It keeps our unbeaten run going and it is another clean sheet. My players played some good stuff at times in a hostile atmosphere.
"We showed a lot of character and we've taken four points off Cardiff so we are not that far off. I am very pleased with the display."