Numerous features and improvements currently related to a portable computing and data collection system are presented. It will be appreciated, however, that although the features disclosed herein are disclosed in connection with a small, portable hand-held system, these features can also be used singly or in combination with a variety of other computing or battery powered devices. Disclosed features include an improved battery pack containing a unique battery temperature-based sensing system, a modular radio system having an antenna board, a radio frame designed to accept any of a variety of different radio boards, a sealed hand-held personal computing system, a light transmissive window that also serves as a door providing access to the interior of the device, and a unique compact flash card implementation. Embodiments containing various combinations and relations of these features in a portable computing system are also disclosed.