I’ve repeatedly tried and failed to run a 54 hour 400G print. Everything starts fine, but a few hours in the actual temperature drops below the melting point of my eSun PLA and it starts printing in air. I’ve run the print both from the SD card and from my Octopi. The last time I ran it without filament loaded and took some screen caps to verify the timing, but I think it’s a little different each time - I’ve seen it go for over 8 hours before failing a couple times. At just short of the 2 hour mark it drops from the set 210 to 194. Then at about the 3 hour mark it drops again to 180. By the 4th hour it settles at 184 and stays there for the remaining 50 or so hours. The whole time the target temp still shows as 210 regardless if printing from SD card or Octopi.
I’ve replaced the heater cartridge to no effect. I’ve also run it with the bed heater disconnected. I’m running off an APC battery backup with a fresh battery and the Octopi (battery side) and lamp (surge only side) plugged into it don’t show any issues, so don’t think it’s the power source, must be internal.