A data collector for use in monitoring a lyophilisation process of a product in a test product container in a lyophilisation chamber, said data collector comprising a battery, a measuring device including an electronics unit and a sensor configured for being arranged in said test product container, a first compartment in a first portion, a second compartment in a second portion, a first end surface configured for resting on the support surface, and a second end surface opposite to the first end surface, wherein said first and second portions are arranged side-by-side when seen in a plane defined by the first end surface, and wherein the battery is housed in the first compartment and the electronics unit of the measuring device is housed in the second compartment, such that the battery and the electronics unit are separate from each other.