I am using a 5.1 V 2.5 A AC adapter. The batteries lasted for about a week, because this is on my office door and I enter and exit many times a day. In the log there is 44 lock or unlock commands in the last 8 hours (When I am at home) I thing the average is about 10-75 commands per day
It is wired up from the + and - pole inside the battery compartment by soldering one wire to the + pole on a AA battery (Dead of course) and one other to the - pole on a AA battery (Dead of course) Since the batteries is connected in series I installed 2 batteries, the + to the start and the - to the end. of course covered the other pole on the 2 batteries to prevent short circuit
The only damage i made to the lockitron was making a notch in the back housing to get the wires out, it is very deep, to the bottom of the back plate
The AC adapter is connected to my UPS so if the power goes out i have about an hour to unlock the door. However should the UPS shut the power off when I am outside I just use the old office key. If I am without power for long times I will just take the cables/batteries off and use AA batteries.
If you use AC power you could use the API and get the lock to never sleep it’s wifi, if you do this with batteries you will empty them in a few days. I only use Bluetooth (BLE) so I do not care about WiFi