What happens to a burglar alarm (just a stand-alone one, not centrally
monitored) when mains power is off for days? I know that the internal
battery will obviously discharge but does it actually trigger the sounder at
any point, or does it just die quietly?

We're going away for two weeks, during which time the house is being rewired
and I don't want the neighbours being disturbed by a shrieking alarm.

TIA