Sorry guys, I didn't provided all the details regarding this issue.
I didn't get any "Batt Light" so I went ahead and loaded the program again into the PLC.
Later the electrical panel got the power cycle by a maintenance personnel and the PLC lost the program again.
I found a new PLC with a new battery and replace it for the old one that was losing the program. After loading the PLC program back into the new CPU, power was cycle to test and the plc program got lost from the CPU.
The old PLC that I removed from the electrical panel, I put it ON a chassis I had in my office. I loaded a program into it, cycle power to it three time and it never lost the plc program.
Could I have an issue with the "Chassis" or the "Power Supply" on the electrical panel where the problem is located that is causing the PLC to lose its program. I forgot to mention that the "Batteries" on both PLC's were measuring 3.5V