The 36M comes standard with the COBRA rechargeable 14.8V LiPo Battery. The module also supports the use of replaceable 9V batteries as a backup option. The 36M firing module also includes 12-24V external power support.
The battery life for the 36M and 72M using 3 x 9V batteries is 8 hours active, 20 hours sleep; using 14.8V LiPo battery, 12 hours active, 30 hours sleep, and with 12-24V external input, the life depends on the mAh rating of the battery as the 36M/72M draws about 50mA in active mode and about 15mA in sleep mode.
When using 9V batteries COBRA recommends that you use Energizer 9V batteries. We have found that Duracell, along with other battery brands, does not produce the proper amount of peak current and typically perform worse in cold weather.