Yes, you might lose 10ºC in the worst case, is that so critical? Nope.
No not critical, it was what I observed in T12 test.
I wanted to experience it to learn.
Will it help having a NTC soldered to the pcb, inside the box, measuring ambient temp, compared to using cpu temp?
Did you calibrate the system? Otherwise you're losing your time, of course the readings will be wrong!
Regarding T245, I power on, T245 profile, NTC OFF, wakeup stand, startup sleep.
Station sleeping displays ~37C in tip, 36.7C in CPU and 25.3C in FG100. Ambient temp. in FG100 is 24.5C.
I started the T245 cold tip calibration, I noticed when the station is trying to stabilize 250, shoots at 800, 900C, but at same time tip is bellow 100C.
It stabilizes at 250 but FG100 measures 112C in tip.
I though something was wrong or I did something wrong and didn't proceed doing a manual calibration.
This in both stations, one I only cut R0, I soldered a short wire to PCB jbc pin (lower 6th pin in a row), then to T245 blue handle wire on the other side (with a crocodile).
T245 brown wire to pin 5 and green wire to pin 3 (using front GX12-5 socket).
-EDIT-
Proceeding with manual calibration:
cal 250 defaults to 900 and measures 110C in FG100.
Increasing the value to max 990 measures 120C in FG100.
I aborted the manual calibration and defaulted to 900.
I also ordered another tip.
Without calibration, waking up from sleep and going to the graph, it displays a lot of huge camel bumps, will take a photo, looks like noise? tip is touching nothing.
Going to the the home screen it displays a steady 320C, with a few occasional jumps to 315,326C, but tip is at 128C in FG100