The battery in my daughter-in-law's Stratus was dead so I tried hooking up a charger to it. When I did, the car alarm went off. So I unhooked the positive cable and then hooked up the charger to the battery. The battery appears to have taken a charge, but when I attempt to reconnect the cable to the positive terminal the alarm starts going off.

Any ideas on what I've done / what I need to do to make the alarm stop when I reconnect the battery cable?