The 36M and 72M come standard with an internal COBRA LiPo battery. The battery capacity is 900mAh and supports up to 18 hours of active operation and 36 hours of sleep mode operation. When the 18R2 that is synced to the module is off or out of range, the module will automatically go to sleep. When the 18R2 is powered on and in range, the 36M and 72M will wake up automatically.
For backup, the 36M and 72M support 3 x Replacement 9V Alkaline (Energizer Only) batteries. The batteries fit into the same battery compartment as the COBRA LiPo. They can be used as a backup in the event you need a quick replacement for the LiPo battery. The 1P battery powers the system operations such as the radio, LCD display, and LEDs. The two 2P batteries are responsible solely for firing cues. By having a separate power source for firing cues, you will always fire at full power, even if the operational battery voltage goes down. The placement and orientation of the batteries are noted on the back of the battery door. If you are switching between 9V and LiPo batteries, make sure to change the module voltage mode.
Although it is not a commonly used option, the 36M and 72M also support external 12-24V DC power input. This battery option is a good fit for permanent installations, such as theme parks or in cases of extremely cold weather, when a single battery needs to power multiple modules. For example, a 12V car battery kept in warm conditions such as a vehicle can power a high quantity of modules wired in parallel to the battery.