The battery cartridge connections of the RBC63, APCRBC107 / 108 and SBATT are very ridged and difficult to manipulate. At times it appears the male and female connectors will not line up.
When connecting the internal battery, it is recommended the customer slide the battery out of the chassis approximately ½ to 1in before attempting to align the battery connectors. Attempting to connect the battery while it is fully installed can be difficult due to the rigidity of the battery cable.
After several failed attempts to mate the two connections, the customer may find two small black tabs on the battery connector have bent over. These tabs should be straightened out prior to attempting to reconnect.
FYI; Too many failed attempts will likely result in these tabs breaking off. This will not affect the operation of the unit and the customer should resume their attempt to connect.