k0ua
Epic Contributor
These are the batteries that I found. I have not seen this type of battery used for anything other than emergency lights.
6-Volt-Lead-Calcium-Battery
Lead Calcium grid plated batteries are often used as PBX backup for long life. They typically cost more than a regular lead acid gel cell, but typically last for several years. In the case of the flooded wet cells used in PBX service they can last up to 20 years if not run all the way down too many times. I have never seen them in this form before.