Angelcare advise the following on your monitor's battery life:
When the Parent Unit is removed from the Charging Cradle in Power Save Mode the rechargeable piles will last approx. 6 hrs.
When the Parent Unit has the video screen on constantly as with all cordless devices this will naturally drain the re-chargeable piles when it is not placed in the Charging Cradle.
In addition to this the amount of noise in each home is different, therefore as the Parent Unit is constantly transmitting background noises, music etc. these will also drain the battery power in the Parent Unit.
It is recommended that should you wish to use the Parent Unit in Video Mode (out of power save mode) for long periods of time that you keep the Parent Unit in the Charging Cradle as per your manual. Please see below for information on how to set the Power Save Mode.
This is indicative of any product (such as your mobile phone) that constantly streams information, video etc. This function uses more power that when any unit is standby/power save mode.
Many parents who wish to constantly stream video and monitor continuous sound purchase an additional Charging Cradle and AC Adaptor from the Angelcare website in order to do so.