Webbie,
Do you mean the white plastic casing with the contacts. If so I changed some of these before. The casing seemed to be sort of welded together but could be prised open with a flat blade screwdriver or similar. The battery contacts are attached to a pcb which in turn is connected to the battery via +ve & -ve and two thermister (i assume) wires. The casings clipped back together but just watch you don't make too much of a mess of the casing when prising it open. Also be careful when opening it that the two springs on the catch don't escape.
Hope this helps
