We should have won it on the balance of chances and our overall performance.Richard Beale
Blues were forced to come from two goals down in the PDL2 fixture, which was played at Charlton's Sparrows Lane training ground.
Despite making the livelier start, Blues were behind after nine minutes when Alfie Doughty fired home from a tight angle.
The hosts then doubled their advantage on 35 when Luke Carey converted from close range.
But Blues hit back just a minute later courtesy of Bailey when he guided the ball home.
Blues had further good chances to add to their account before they finally fashioned a leveller with just four minutes remaining of normal time, after Geraldo Bajrami's free-kick found Martin who headed home a deserved goal.
Senior Professional Development Coach Richard Beale admitted that his his side could have done better with their defending but was generally pleased with their performance.
"We gave away two cheap goals, despite playing well and creating several chances," he said.
"We showed good character to come back into the game and we should have won it on the balance of chances and our overall performance."
Martin's late goal maintained Blues unbeaten start to the league campaign.
They are next in action at the St. Andrew's Trillion Trophy Stadium on Saturday against Colchester United (kick-off 12 noon).
Blues Under-23s: Jake Weaver, Ben Forrest (George Baker, 70), Geraldo Bajrami, Josh Martin, Steve Seddon, Olly McCoy (Ben McLean, 85), Ryan Stirk, Cameron McGilp, Tom Anderson (Ryan Burke, 60), Kyle McFarlane, Odin Bailey. Sub (not used): Michael Luyambula.