The 18M will operate in the temperature range of -30°F - 130°F, however at extremely cold temperatures, your battery life and firing power are reduced.
Between -0°F, 1 igniter max
Between -0°F and 32°F, 2 igniter max
Greater than 32°F, standard maximums
While not required, it's suggested to minimize the amount of time the battery is spent in freezing conditions to optimize the performance. For example, if the temperature is -30°F, and you have the opportunity to keep the LiPo batteries and place them into the modules 45 minutes before showtime, this is better than leaving them in freezing temperatures outdoors for eight hours in advance.
Customers are also known to using a chemical-based hand warmer pad to keep the batteries warm within the module when they cannot be removed from the system to be kept warm. The hand warmer pad can be placed between the battery and the battery compartment. In some cases, removing the battery compartment can help free up room for you to secure the battery pad.