The Addicks, who saw Igor Vetokele open the scoring, have now drawn seven of their 11 league fixtures, with Davis scoring his first Birmingham goal to earn Lee Clark’s side a deserved point.
Both sides went into the game on the back of midweek victories. Charlton had won 1-0 at leaders Norwich on Tuesday while Birmingham returned to south London having beaten Millwall 3-1 at the New Den that night.
The home side had to do without Israel international Tal Ben Haim however as the experienced centre-back was observing the Jewish holy day of Yom Kippur.
The first clear chance was Charlton’s with Vetokele turning marker David Edgar on the right of the box. A goal looked likely but although the striker curled his shot past goalkeeper Darren Randolph it fell beyond the far post.
Vetokele made no mistake with his next opportunity though, burying a header in the 11th minute after a spell of patient possession eventually saw Frederic Bulot swing in a cross from the left that found his team-mate right in front of goal.
Birmingham responded with a spell of pressure that ended when Davis miscued a first-time effort harmlessly wide and there was a let off for the home side when Yoni Buyens dithered to allow Callum Reilly to set up Clayton Donaldson only for the striker to blaze over.
Koby Arthur poked the ball into the Charlton net after 33 minutes after a great run round the back of the home defence by Paul Caddis but the goal was ruled out because Donaldson was offside, although the latter did not touch the ball as it went past him and was not impeding the goalkeeper.
The half ended with defender Andre Bikey-Amougou sending a header from a free-kick just over the Birmingham bar.
The second half began with Vetokele setting up Lawrie Wilson at the back post only for the Charlton midfielder to fire over but the home side soon had goalkeeper Stephen Henderson to thank for keeping out Paul Robinson’s header from a free-kick.
Birmingham were level in the 53rd minute when Stephen Gleeson found Davis on the left of the box and the midfielder turned before planting a low drive across goal and beyond Henderson’s reach.
The home side saw Chris Solly burst forward only to fire wide but Birmingham remained dangerous and substitute Wes Thomas could have won it for the visitors late on had he not slipped in the act of shooting.