SMX3000RMLV2U faults after power failure

[SubnetMask]

I have two SMX3000RMLV2U units running my 'home lab', which have been working fine for some time. They periodically go on battery due to 'distorted input' without issue and return to line power after a few seconds. 

This morning, we had a brief power failure where the power flickered a bit and went out for 10-50 seconds, came back for 15 seconds or so, went back out for another 30-90 seconds and came back, and has been on since. When the power went out, both units dropped the load and everything came down hard. This has never happened before with these. While the power was out, both units still were powered on, with one indicating 'The battery voltage exceeds the nominal battery voltage rating.', yet it was at I believe 79% SOC, and below the 132.6V the other unit indicates at full charge, and the other indicating 'PFC Fault'. When the power returned, the one indicating 'excessive battery voltage' returned to supplying power to the rack, the other did not. The one indicating 'PFC Fault' appears to have returned to normal function after I unplugged it from the wall and disconnected the battery and let it sit for a few minutes. 

The unit indicating 'Excessive battery voltage', I noticed afterward, was no longer holding charge level - with both units supplying the load, I unplugged the one with the 'Excessive voltage', and it kept supplying power to the load from battery. It may have been indicating 'The battery voltage exceeds the nominal battery voltage rating.' for a bit, but it's always kept the batteries full, and they've always been near or below 132V. Now after this event, it's not charging the batteries and the SOC continues to drop while on grid power.

The unit that was indicating PFC Fault, as I mentioned, seems to have returned to normal operation after removing all power for a few minutes. From what I've read, 'PFC Fault' is usually a non-recoverable error that required repair or replacement. With the first unit supplying the load, I unplugged the one that was indicating PFC Fault from the wall, and it too kept supplying power off battery.

The batteries in both units are 6-8 months old.

It seems that something about this power failure did not play nice with these units. and may have damaged one or both of them. 

These units are well out of warranty, purchased second hand, so I'm not expecting APC/Schneider to do anything, mainly looking to see if anyone else has seen anything like this and if the cause was determined or known.

Has anyone seen (mis)behavior like this with these units or similar? Any thoughts/suggestions? 

[JonPro]

Hi @SubnetMask 

Thank you for reaching out to the SE Community, my name is Jon and I will assist you with this query.  Apologies for the late revert, may I ask if you have a network management card installed on the UPS or PowerChute Business Edition on a computer that is monitoring the UPS that is showing excessive voltage?

We can download the log files from them and see what kind of event it has encountered.  I also recommend that you do the cold start and brain dead procedure on the UPS and see if it'll make any changes.

Video: How to perform a cold start and brain dead on Smart-UPS