Please elaborate on cold start condensation, specifically to smart motors sealed in water-tight, and partially air-tight housings. Even in a nitrogen purged enclosure, there will still be moisture in the air, even within the elecetronics PCBs, rubber components, and potential ingress of outside air in limited quantity from leaky seams. The Alaskan pipeline case study touts operation below -40C, which my application desires as well.
You explain condensation may deposite on the encoder wheel and disrupt position feedback, but this is not permanent damage. Is there any permanent damage potential from condensation on the motor electronics or motor coils?
Can the motor boot up, check it's temp first, and pause in an MTB wait state for the coils and PCB to self heat and burn off the moisture? If no power should be delivered to the motor until an attached heater warms up the motor, it will add additional user or host processor monitoring, as well as a power efficiency loss to actuate a lossy relay or MOSFET on the power line.
For the upper limit, is 85C the ambient temperature, or internal thermister? What ambient temperature range can be expected to overheat the NEMA 17 and NEMA 23 motors running intermittantly?