I have a Scantronic 9448ES with 2 x 9427 remote keypads. Whenever the mains power fails, the external bells sounds until power is restored and then the internal bell sounds until you enter the access code. I have checked the battery in the control unit and that is fine.
It has only just started doing this recently as it never used to!!
Many thanks

Stuart Fitz, October 2007

When the mains power has failed and the panel is running on the internal battery does the power LED flash off and on slowly?
Did you put a small load on the battery when checking it?
Symptoms are that the battery is low.

Ticktock, December 2007

Not sure how you checked the battery if you have only measured for 12 volts then you may find that under load the battery cannot sustain the current required for your system - try changinging it for a new one, 12volt 2.1amp. any more questions email me paul.shade@ntlworld.com - good luck

paul - security installer, October 2007