These display modules are easy to work with and provide bright and clear indications.
For temperature display, feedback from the blood bank staff suggests that the bar graph type might be a good starting point. It could be illuminated in a thermometer-style display: the number of illuminated segments increases in proportion to the temperature. The exact temperature, as well as the acceptable temperature range can be conveyed with static markings next to the display. The color of illumination can communicate significance of the temperature reading (e.g. green = good, yellow = close to range edge, red = out of range).
For battery level, the bar graph will likely be a good choice as well.