I had similar but I got bored with replacing the batteries.I know you can use a DC power supply but just to add to the thread,which is excellent:
The cheap,"Cyclone" alarm I have on my SV650,
http://forums.sv650.org/showthread.p...hlight=cyclone
I could quite easily fit another to my garage door inside near the hinge side and wired to one of my old 12v Car batteries.This would last around a year on that kind of battery.They are REALLY loud and easy to Arm and Disarm and have key-fob adjustable sensitivity.