Leyton Orient assistant manager Kevin Nugent admitted his side failed to replicate their first-half showing after the break as Charlton hit back to win 3-1.
Scott McGleish headed Orient in front but the Addicks were back on terms five minutes after the restart when Paul Benson tapped home.
Bradley Wright-Phillips fired Charlton ahead and Jose Semedo`s header sealed the points
Nugent said: "In the first half we thought we played quite well, still not as good as we would have liked to have done but we didn't start well at all in the second half. That was disappointing for us really.
"Key decisions didn't go our way. We had a goal disallowed and then a minute and a half later we are 2-1 down.
"There is still a lot to play for this season. I've not seen any other results today but there are a lot of points to play for, so certainly the players and ourselves won't be giving up and we will be going right until the end of the season."