bigbill bmw520i

[bigbill]

Hi,Does anyone know how to disarm the alarm system on a 1995 bmw 520i the alarm is the 3tmodel and has one button on the key fob.The problem i am having is if i let the car sit for a few days it will not start.i think the alarm system is the problem as i have checked the battery for charging and any drainage.The alarm system is so sensitive i think if the battery drops below 12volts it will not let me start the car.Anyone any ideas?
Bill