BatteryZzz 2.0: Low Battery Alarm for Windows Mobile device - MSPoweruser
Battery Alarm Download: Easy and configurable system tray application that monitors the battery life and alerts users on low power via messages and audio
Low Battery Voltage Indicator Alarm
Battery Low Voltage Detector with LED & Audible Alarm 4-16.8V LiPo & 4.8-6V
Low Voltage Alarm Circuit
LM358 12V On-Board Lithium Battery Low Voltage Alarm Buzzer Lipo-Lion Under Vlotage Protection Module LED Indicator Alarm Module : Amazon.ca: Industrial & Scientific