I have always been curious on how and when the rechargeble batteries in the alarm/siren are recharged. Is the car battery continuously charging the alarm/siren even when the car is off or does it only occur when the car is running? If it's the later, then what happens when the car is in winter storage, or the car has a dead battery. How do these factors effect the longevity of the rechargable alarm/siren batteries? It is assumed that cars in hotter climates will have their batteries degrade faster.