Helge Sensor cooling over 90% performance (to -20c°)
Your 12V supply/cable might be stressed. Did you measure the under-load voltage at the cemra itself when running under such conditions?
That percentage is not a performance value, but how much the cooling system is stressed. Try to keep it below 90% all the time (already more than 2.5A).
Unless you are in a Bortle 2 zone and running exposure times of 1000 seconds or more, the dark current noise of an ASI2600 is not going to change SNR perceptably between -10ºC and -20ºC. Just knock it to -10ºC, and your current power supply and power cable may be able to handle it better.
Otherwise, you need a power supply (just for the camera) that is good for 5A or more capacity just for the camera (and not droop by more than 0.5V under 3A load), and at least 18 AWG cable that is no more than 3 meters long. Remember that a "3A supply" already droops outside its specs when you run it at 3A; and the cheap ZWO and Amazon power bricks may not even meet their own specs.
I did a test run at home (3 x 60 images, cooling 50% performance) and there were no problems.
At 50% stress, your power supply now only has to handle 1.5A, and that could be the reason why it worked fine.
Chen
