A power outage resulted in an indoor temperature drop to -5 Celsius at my Kongsfjord location. When I got power back on, the Perseus (several of them) restarted at around 10:25 UTC. I got some heat in the room, then left around 11:00 for some errands.
I returned at around 12:00, and continued to heat up the room. At around 14:30 the temperature is 20 Celsius. The Perseus "moved" a bit more than 6 Hz at that time and temp span.
I think that's quite a decent result. And the Perseus does run at sub-zero temperatures! Outdoor is -10 C and gale force winds.