This paper is going to look at real life aged 80+ year old Nickel-Iron cells that are still functional and will explain the simple recovery techniques that were documented in an original Edison Alkaline Storage Battery brochure from the 1920’s.
Some of the cells had been charged intermittently, many had sat off charge for many years, and some had sat off charge and all but empty, but  all  made very substantial recoveries, and when subjected to discharge testing that followed the guidelines of the IEEE 1115 they all were able to pass load tests at their applicable rate.