Min Voltage devo 7e

Minimum voltage on batteries of devo 7e. Because I often panic happened 5,84v.
What is it normal operating voltage knowing that it is equipped with an internal UBEC. I thought that was the minimum 5v

it has an very ldo reg (drops about 0.3V) so minimum pack voltage is about 3.8V to stay safe, though 4V would be a better area to set your alarm for i think