Bests & Worsts Reviews from Amazon

The basic gist of the battery problem is that the lock has two modes of motorized operation: low energy and high energy (this is clearly described in the manual). When you install the lock, you *need* to make sure that the hole for the deadbolt is big enough for it, aligns correctly, and leaves room for expansion from heat (if you live in a climate where this is a concern). If everything is right, the lock will use low energy, and your battery usage will be low. How do you know you're using low or high? After you initially set up the lock, the lock will try low energy first, *then* if it can't move the bolt, it will go to high energy. It will do this the first three times you open/close it (again, this is all in the manual). Each "try" is a pair of sounds (so if it sounds "brrr [pause] brrr", that's one try). If it goes three times without being able to use low-energy, it will use high-energy ALWAYS. Hence, lots of batteries. As for everything else, there are enough reviews out there. The product works as advertised, and is very high quality. If you don't have a deadbolt already, or it gets kind of stuck sometimes, or you don't trust you can get a smoot motion for the bolt, spring for a professional installation. It is worth it to avoid wasting money on batteries.