Our Stake has key card locks on all exterior doors, stake offices, bishop and clerk's offices, libraries, baptismal fonts, and mechanical closets. The locks are like the ones at most hotel and motels where you insert the card key in a lock and pull it out. The light flashes green and you can open the door. A number of stakes in our area had them installed about 8 or 9 years ago.
When the locks were installed, our stake asked for permission to purchase the hardware so we could issue the keys and control them. This would be done at the Stake's expense. We were advised that this was not allowed and the FM Group was required to control, maintain and oversee the hardware. Our FM Group is very good at issuing the keys we request.
It is great for managing keys. You can program keys for a few days, months or years. Our FM Manager codes the keys to expire every 2 years. We then re-issue new ones. If a member is released from a calling and won't return their key, or has conveniently lost it, a new key can be issued to deactivate the old key.
They can be programmed allow access to different levels -- common level for all common doors such as the front door, baptismal font, kitchen, etc. A higher level which includes a ward's bishop and clerk's offices or even on the stake presidency's level which opens all key card doors in all 5 buildings in the stake.
The great part is our Stake President only needs to carry one card key around with him which gets him into all of the buildings and any other door with a key card lock.
Magnetics and cell phones can deactivate the key cards. It is amazing how many people don't realize they have a magnet near their key card. One bishop was asking for a replacement key every few days. I told him he needed to be careful and keep his card away from magnets. He said he did and showed me he kept his card in his side coat pocket. Right under his coat pocket was his cell phone. His cell phone clipped to his belt and there was a magnetic closure to keep his phone in place. When I pointed this out to him, he had a Homer Simpson moment - "Doh!"
This system is only made for a limited application and can be very expensive. Our FM Group used this system for 5 or 6 stakes which included some 30 or more buildings. It wasn't designed for this many buildings with all of the potential levels of access in 5 stakes. As a result, we overburdened the system and after so many problems, most of the building are having the locks removed and regular metal key locks installed. If there was one system per stake, it would work fine, but it can be expensive if you run into problems with the locks. Only a factory representative can work on the locks.
If a battery goes dead, then everyone is locked out. They are supposed to flash amber when the battery is getting low, and then the battery can be replaced. However, we have had many instances where the battery just goes dead, and you can't get in. If the lock is completely dead, the memory is lost and the lock has to be reprogrammed.
All of the interior key card locks have a high security metal key lock in them as a back up. We were only issued one of these metal keys for our stake. If a lock was dead, I often got calls to come open a door. The exterior door locks did not have a back-up metal key lock in them. We never had an instance where anyone was locked out of a building because the battery died. This was because we had more than one exterior door with a key card lock.
As a number of stakes in our area are converting back to metal key locks, our stake is hopeful that we will be the only stake using these locks. When this occurs, then it shouldn't be a problem. Our Stake President want to keep the system in place. He like only caring one key with him.
Our area was experimenting with these types of locks. It was deemed a failure because the system was overburdened, any repairs from the factory were expensive, and it consumed too much of the FM mechanic's time to reprogram or replace batteries. Maybe there are other systems that could work, but the system we used was not recommended for use in other areas.