I have a second gen motion sensor that is going throug its battery in a week or less. I called in and all they had me do was remove it at re-pair it to the hub and said that should fix the problem. The CS-Rep also said that the device might need a firmware update but he couldn't perform the procedure. Why? Why aren't firmware updates auto pushed to my devices when they are required?
My motion sensor is still destroying batteries. I have taken it out of service as the battery usage is rediculous!
If you can get a hold of a battery reading device that you put the batteries in and it digitally returns whether or not the batteries are truly dead or not, it might be of some help. It might be simply a case where the motion sensor is misreading the battery level and the device itself needs replaced. Either way, it's obvious that you can't continue replacing batteries weekly. My motion sensor batteries have never been replace yet and it's been close to 6 months.
I had one that did this a while back, took it back to the store and swapped it as defective, and didn't have anymore problems.