• If the Handheld lights all 6 LEDs and does an 3 second beep immediately upon pressing a button the Handheld has a low battery and you should consider changing them soon. The unit was designed to still have several hours of working life upon first detecting a low battery.
  • If the Handheld only lights the LED just polled and also does the 3 second beep that is your indication that the Sensor unit just polled has a low battery. The unit was designed to still have several hours of working life upon first detecting a low battery.