Only one of the previous 14 games between these two had produced more than two goals, so it came as no surprise that this was another tight encounter of few opportunities.
There was little to speak of in the opening exchanges before the hosts had numerous sights of goal in quick succession midway through the first half.
Strong work from Greg Docherty in midfield teed up Lyndon Dykes, but the striker’s effort from 30 yards was off target.
Moments later, Harry Clarke found Kai Wagner in the way of his goalbound effort, and from the resulting corner Blues keeper Ryan Allsopp did enough to divert the ball away from Connor Coventry.
It was the same story after the break, and Blues’ backline was called into action again when Campbell found himself clean through on goal, and it took a perfectly-timed challenge from Klarer to keep the score goalless.
The breakthrough came with just under 20 minutes remaining from Kelman’s first touch after coming off the bench.
The striker brought down a long throw-in that had been flicked on, and fired home beyond Allsopp.
Birmingham – who had made five changes from the 3-1 defeat at home by Middlesbrough last time out – threatened late on via a counter attack that saw Ibrahim Osman fire just wide, but ultimately slipped to a third straight league defeat.
Miles Leaburn almost added some gloss to the scoreline for Charlton in injury time but could not direct his effort on target.
