There are two key issues with smart locks: power consumption and battery life. These issues are, of course, related.
Power consumption is an issue for the manufacturers. Power consumption limits the features that can be added to the lock. For instance, a vendor might want to upload video from the camera to the cloud. But, recording and uploading drains the battery and shortens battery life.
Battery life is a consumer issue. If you forget to replace batteries, you might find yourself locked out of your own home. Some vendors offer a +9V battery plug for emergency operation. If you’re one of the rare folks that leaves home with your keys, phone and a +9V battery in your pocket, you are all set. But if not, the +9V connector does not help you. Other vendors offer a solar cell that can charge a bit off the lamp function in your phone. Innovative, but is it worth it? Even if you remember to replace batteries, it is not convenient. Technology should make our lives easier, not add maintenance chores.
Instead of batteries, you could wire the lock. This would entail routing electrical wires through the door. This might be a difficult or an expensive process.
Is there a better way?
By integrating a wireless power receiver into the lock, batteries are no longer a problem. The lock receives all the power it needs to enable new features such as video recording. The manufacturer can stop worrying about power budgets. The end customer never needs to replace batteries. Wireless charging eliminates the trade-off between functionality and battery life. Customers can get both functionality and convenience. And they don’t need to carry a 9V battery in their pocket.
The video below shows a demo of a smart lock with integrated wireless power.