HP R5500 UPS power remaning indication?

[Mandosa]

We have some work to be completed in our server room that requires a brief power outtage (10-15 min)  Is there a way to tell with these UPS's that they are getting close to shutting down?  I'm thinking without connecting anything to the serial port.  The front panels only seem to indicate %  usage, not battery capacity.  Does it make any beeping or any indication when it is about to shutdown?

thankyou