I've seen an explosion on the market of keyless door locks, keyless dead bolts, and so on. Schlage sells a bunch. From the looks of it, most of them are powered either by a 9V battery or some number of AA batteries. Since there's always an actual key slot, you can rest assured that you can still get in even if the battery dies. But what I'm wondering is if there are any keyless locks that don't require a battery? I'm not sure if such a unit exists in the first place. For something like that to even be possible, you'd likely have to run some power wires through the door frame somehow. I am not sure if that is even possible to do, or if any such unit exists. Are they all battery-powered, or is it possible to have a hardwired keyless lock?
There are mechanical combination locks.
I've seen hinges that carry power in commercial settings. I became aware of one in an office I worked in, when it started having issues and heated up a bit.
A bit of googling and I found that Stanley makes one for about $100
Another option similar to the electric strike is a Maglock or Electromagnetic Lock.
The door needs to be ferrous, so if its not mostly steel then a steel plate needs to be securely fastened to the top corner.
The magnet is mounted under the lintel and wired to a power source. When power is applied, the electromagnet attracts the door with hundreds of kilograms of force, which is more than you can generate by yanking on the handle.
- Doors can all be locked and unlocked by a building control system on a timetable.
- Doors can be briefly unlocked by a swipe card / proximity tag reader and then immediately lock again, to limit tailgaiters.
- The door's state can often be read by the maglock - so if someone has wedged the door open then the current drawn by the energised lock is different, so the building control system can raise a "door not secured, please check" alert.
- You have to be mindful of tall people though - losing a couple inches out of an average door height puts it into head-banging range for taller people, which is unpleasant.
- The door lock requires power to stay locked - in the event of power failure, the door will fail to an unlocked state. They're normally backed by an alarm battery good for days, but these can be forgotten. The fix is to have a secondary key lock, and after a day of no-power someone has to go in and lock the doors with the key.
- Cost - there's wiring to be done to each door, and a steel plate fastened to the moving part.
- These don't work with sliding doors, but they tend to have motors which can simply be turned off achieving a similar goal.
- One failure case is if the ferrous plate has come off the door then there's no way for the sensor to know the door is insecure. I saw one that had been in this state for possibly years, but noone had tried it when locked.
- Lastly, these are not bank-vault grade locks. Hundreds of kilograms can be generated by a vehicle yanking at the door via a chain. However this will still slow a forced entry giving time for security guards to respond.
There are systems like Opera iControl that allow to have (possibly custom) control unit next to the door frame. This unit is responsible for decision for opening the door and can be mains powered.
The part inside the door itself is battery powered, and activated by the coded infra red signal from the control unit. The IR sender is embedded into the striker and is both powered and activated by the 12 V input that can come from anywhere.
The "in door part" uses very little power to move the tiny control latch somewhere in the lock. The much larger deadbolt is then moved by a human pressing the handle, but for the outer side this can only be done if the control latch permits. The battery finally needs replacement or recharging, but under the normal door usage (few openings a day) it can probably last for many weeks.
These locks can always be opened from inside, with and without batteries, locked or not, by just pressing the handle. From outside, they can be opened with the key if the battery dies.
I have seen many such locks in the hotels of Italy.
While not provided by the manufacturer, it may be possible to design some kind of induction charging for the battery in the lock, with sender and receiver coming into proximity when the door is closed. Both chargers and receivers are available on the market. Depending on where does the door is, a solar battery may also work.