Dell UPS Tower 1920W HV shuts down without shutting down the server

Hello everybody,

We purchased a Dell PowerEdge T620 and a Dell UPS Tower 1920W HV. The server is connected to the UPS by USB cable and runs the Dell UPS Management Software. We don't run the newer ULMN because shutdowns cannot be scheduled, which is something we need.

Fully charged batteries should run for around 6 hours after a power cut, that's what is displayed in the management software and on the UPS itself. However, when a power cut occurs, the batteries only last for around 3 h 30 min. The problem is, that a "Battery Low" event does not even occur, so that the UPS eventually shuts down (or dies because of empty batteries) without shutting down the server gracefully.

That is very strange because scheduled shutdown (every evening) works like a charm.

I hope you can help me with this issue.

Cheers