Last night, I had the A-P 10" Mak-Cass and the 20" Starmaster out on the driveway side-by-side, from sunset 'til 8 pm. By 8 pm, it was 20°F outside and white frosty all over the scope tube and dob shroud. Good thing there was no breeze this time. If there's no breeze, it's actually not too bad. The crisp air drains all of the moisture out. I'm getting used to this, as long as I can get good viewing. That doesn't mean that I'll cancel my move back to CA next month. I still dream of those warm balmy summer evenings outside 'til 3 am. I was I could view the winter sky under those circumstances. A move to Australia would accomplish that.
My two small red LED flashlights had trouble working. One wouldn't light up at all outside after an hour of use until it thawed out back inside the house. My Kerndick 12V 33AH big battery was on the ground for three hours under the NJP160 mount and worked OK. My smaller 9V 12AH dob battery (in the Starmaster rocker box) konked out after a few hours of running in the sub-freezing temps. Batteries start malfunctioning at freezing temps and lower. If you can, leave your mount batteries inside your car and run an extension cable out to your scope. That's hard to do with a dob but I've had good luck doing this with an equatorial mounted scope. A battery lying on the ground in freezing weather under the scope will stop functioning sooner than you think.
The seeing never got that sharp in the three hours I had things outside. The jetstream was back in full force overhead along with the typical valley air layers I get in wintertime.
The temperature of the garage that stores the Mak has been about 50°F. I set up the A-P 10" Mak-Cass in 30°F still air a half an hour before sunset. I oriented the tube horizontally and so that the eyepiece end was higher than the corrector side to let any hotter air out of the tube. I left off the dew shield to hasten the corrector's cooling. A half an hour later, I started observing Jupiter as the sun was setting using a 16mm Zeiss Ortho eyepiece giving me 231X. Jupiter's image was a bit soft but I could immediately see the receding GRS, 6-7 belts and oval detail within the zones. The Jovial moons were dancing a bit but each showed good disk definition. The 20" Starmaster next to the Mak showed a brighter a more colorful Jovian disk that was twice as soft due to mirror cool-down and the mediocre seeing. Saturn showed the same ring and ball detail in the A-P Mak from the beginning (a half an hour after setup) 'til I ended the evening's observing at 8 pm. I was able to see as much Jovian and Saturian detail within the first half an hour after setting up as I ended up seeing during the remaining three hours. As a test for seeing, I pointing the Mak to Castor, in Gemini, and could barely resolve this normally easy double. The double's two stars were immersed in eachother. Switching eyepieces to a 27mm Panoptic, I did get to enjoy some wider field observing of a few wintertime open clusters and M42. The Trapezium in M42 looked fairly well resolved at 371X with a 10mm Zeiss eyepiece, with its four ABCD stars as fineer points than thay looked in the 20" Starmaster. The E and F stars were nowhere to be seen in either scope, though, attesting to the worsening seeing. So, the seeing was getting worse as the evening wore on. If the Mak was getting more temperature stable but the seeing getting worse, then the images might look the same to me as my three hours passed. My only conclusion is that this Mak is cooling down in about half the time that my past Ceravolo 8.5" f/6 Mak-Newtonian did, even with it's fan running. The Ceravolo took at least an hour to stabilize in freezing weather and sometimes, it would never stabilze in constantly changing temperatures-as during those hot summer evenings on warm parking lot surfaces.