The Bulls dominated for long spells of the contest at Osdal, leaving a try brace from Kieran Dixon and a further score from Will Lovell as scant consolation.
And Powell was quick to voice his frustration.
He said: "We were out-enthused and that is what disappoints me the most.
"We did not have the energy from the start of the game and that is a concern.
"We had a lot more reason to come out strongly than they did and we didn't.
"We are very disappointed that after everything we said and did in training this week, we came out and performed like that."
The result sees the Broncos stuck at the foot of the table.
And the coach insists he will leave no stone unturned to reverse that before the end of the campaign.
Powell added: "I want to win games and that is why I want to coach the team.
"There might be this perception that it does not matter to London but that is not the case.
"It is not in my nature to accept losing games and we will be working very hard to put that right over the coming weeks."
An obvious bright spot for the Londoners at Bradford was the performance of Kieran Dixon, who burst over for two tries right out of the top drawer.
And Powell accepted more players have to follow the lead of the speedy winger.
He added: "The pattern through the year for us has been the younger players doing well and outshining the more senior players.
"The positives in our games have often been Kieran, Dan Sarginson and the like and if the senior players had stepped things up we might not have been in this position.
"But it is all about the development of them and the club and they are learning week by we
