An emergency system including an auxiliary power supply, a charging circuit, a brown-out circuit, and a controller unit. The auxiliary power supply connected to a device. The charging circuit having an input voltage, provided by a mains power supply, and an output, configured to provide power to the auxiliary power supply. The brown-out circuit operably connected to the charging circuit and configured to sample the input voltage. The control unit receiving the sampled input voltage and activating the device when a brown-out condition is detected, the detection based on the sampled input voltage.