The battery pack in my Explorer XS is labeled "12 volt" and the one that came with my E-Trac is labeled "9.6 volt". I know the alkaline pack is 8 X 1.5v AA batteries and should be 12 volts if they are in series. So my questions: Is the E-Trac rechargeable pack mis-labeled? or is the new alkaline pack wired in a series/parallel configuration to make 9.6 volts? Are the battery packs interchangeable between the two detectors?