SMX1500RM2U Run Time Issue

[BillP]

Hi all, I have a SMX1500RM2U with an external battery SMX48RMBP2U. I'm currently trying to troubleshoot an issue where the UPS is reporting an 18hr. (and change) run time which I know is not the case. 

This started when I had the SMX1500RM2U by itself and did a test by unplugging the UPS from the wall to test out the run time. At the time, the UPS reported a 6 hr. and change run time but only lasted less than 30 minutes with an 8-9% load. I let the battery charge up and did a calibration test which led to the 18 hr. run time report.

Thinking it was maybe the battery, I took out the battery in the SMX1500 UPS and connected the SMX48 external battery which has two batteries with newly installed cells. I let the batteries charge to 100% and also added more load to the UPS which is now about 28-30% load. I unplugged the UPS from the wall and the run time percentage went from 100% to 18% and remained there for about a minute or two before I plugged the UPS back in to the wall (I didn't let it sit longer as I had servers connected which needed to remain up). During the time the UPS was unplugged, the run time was still reporting as 18hrs. even though the percentage reported dropped as mentioned above. I then ran another run time calibration test when the UPS reported 100% but no change to the run time when the test was completed.

During the tests, the battery percentage would drop but the run time remains at 18hrs. Is this an issue with the batteries or with the UPS unit itself? Let me know what other information I can provide.