Have you disabled/removed all your mods and add-ons?
Yes
Are you using Developer Mode or made changes in it?
No
Brief description of the issue:
During a completely normal flight, at FL390 at M0.82 the batteries suddenly started to heat up, and to very high temps. Is there something I forgot to do? It’s never happened before. They are now at 1600degC which I’m sure would mean they were on fire in the real world. 
But the plane continues OK.
Edit: They finally stopped increasing in temperature at 1855degC. 
Still no smoke or flames inside our outside
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Edit 2: I then spotted that the environmental control systems seems to have gone nuts. The cabin temps were way up in the multiple hundreds of degrees, and the cockpit temps were negative hundreds. 
See below.
Also, as time goes by in the flight, the high temperatures of both cabin and batteries is recovering towards normal over the period of around 70 minutes. Maybe this is significant?
Edit3: Here was are 1.5hrs later and everything has returned to normal temps. Battery, cabin and cockit. everyone in the plane is fried to a crisp or frozen to death, but the plane is fine. 
I cannot see that I did anything to cause this, so I assume it is a bug or oversight in the current beta code.
Question to the Devs… Could the extreme outside temperature of -68degC haev triggered this behaviour in the plane?
Detailed steps to reproduce the issue encountered:
Just a normal flight on AP at FL390. It’s particualtly cold outside over central Canada at -68degC SAT.
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