Before moving in to our new office, we in IT needed to setup user pin numbers for our front door lock. We quickly found that the battery that keeps it running was dead. It was a five cell 7.5v battery. After looking online we couldn’t find any that could be delivered as fast as we needed.
After taking apart the existing battery pack I found that it was just 5 normal AA batteries (Duracell) soldered together and connected via a small connector. It seemed so unnecessary to me. Why go through all this work for 5 batteries that will need to be replaced?
I wanted to add some sort of bracket that would allow batteries to be replaced regularly with ease. I came up with a small 3D printed insert that would house the batteries inside the empty space in the lock.
After routing some wire to contact all the batteries in the correct series I reused the connector from the old battery to get the lock up and running.
As of the writing of this post the door has been running for about a year!