The BR lithium coin cell battery is specified to -40C => +85C. Operation outside that is not guaranteed. A little below that, the electrolyte freezes, expands, and can damage the battery seal or separator, causing the electrolyte to leak out when the battery thaws. Common BR chemistry electrolytes are PC and DME.
- PC (propylene carbonate) freezes at -48.8C
- DME (dimethoxyethane) freezes at -58C
Additionally, at high temperatures the battery life is significantly reduced and the temperature values get capped at -41C and 86C so the data logger will clamp readings at the extremes.