I posted two pictures at this link below.
http://f1.pg.photos.yahoo.com/ph/mlc...+stuff&.view=t
The left picture shows the detachable charger.
The charging system is simple, there are two metal tabs on the bottom of the car that lay vertical that slide up against the metal strips on the drive through charging base.
The cars cannot be charged in reverse because there is a little tab of plastic on the car bottom that must go into the groove on the charging base to allow the charging tabs to connect.