[Nexus 5X General] roofrider:
Update

Couldn't arrive at anything conclusive. Only have a bunch of screenshots lol.

Charged the phone from 3:55 pm to 5:35 pm. So in 1 hr and 40 mins of charging with screen on, it went from 4% to 84%. However, during this period I only had Ampere open so there wasn't anything CPU-intensive going on. The intention was to find out the charging rate at different temperatures.

According to my thermal-engine-8992.conf and my understanding of it (or lack thereof), the threshold temps are 36°C and 39°C, and thresholds_clr are 34°C and 38°C. Now I'm not entirely sure at which temperature the throttling starts, but from my observations I'd say it is at 39°C.

Screenshot 1: Time: 3:58 pm. In 3 minutes of charging, it went from 4% to 7%. But as soon as the temp crossed 39°C, the amps dropped from 2670 mA to ~500 mA. Temp: 39.2°C

Screenshot 2: Time: 4:02 pm. It went from 7% to 10% in 4 minutes. Amps: ~500 mA. Temp: 39.2°C

Screenshot 3: Time: 4:17 pm. It went from 10% to 21% in 15 minutes. Amps: momentarily at ~2640 mA before dropping. Temp: 38.2°C

Screenshot 4: Time: 4:20 pm. It went from 21% to 23% in 3 minutes. Amps: dropped to ~500 mA. Temp: 40°C

Screenshot 5: Same stats as above. Time: 4:20. Level: 23%. Amps: momentary jump to ~2670 mA. Temp: 40°C

-At this point I reduced my interaction with the device in hopes that the temperature will drop below the 38°C threshold, and it did-​

Screenshot 6: Time: 4:26 pm. It went from 23% to 28% in 6 minutes. Amps: ~2660 mA. Temp: 37.5°C

Screenshot 7: Time: 4:36 pm. It went from 28% to 33% in 10 minutes. Amps: ~2670 mA before dropping. Temp: 39.5°C

-Now I wanted to get the temperature well below the threshold, so I grabbed a bunch of stuff from the freezer and buried the 5X. Things started to get a bit interesting here. Regardless of how low the temperature was, the phone never drew more than 1840 mA-​

Screenshot 8: Time: 4:48 pm. It went from 33% to 44% in 12 minutes. Amps: ~1840 mA. Temp: 33.7°C

Screenshot 9: Time: 4:55 pm. It went from 44% to 54% in 7 minutes. Amps: 1840 mA. Temp: 29.7°C

-I wanted to get the temperature back up to the threshold, so I fired up YouTube and removed the icepack-​

Screenshot 10: Time: 5:07 pm. It went from 54% to 68% in 12 minutes. Amps: eventually dropped to ~520 mA from 1840 mA. Temp: 37.2°C

-Brought the icepack back on to check if temperature reduction would increased the charging rate. However, the draw was limited to ~1000 mA this time regardless of the low temperature-​

Screenshots 11: Time: 5:21 pm. It went from 68% to 75% in 14 minutes. Amps: ~970 mA. Temp: 33°C

Screenshots 12: Time: 5:24 pm. It went from 75% to 77% in 3 minutes. Amps: ~1090 mA. Temp: 33°C

Time: 5:35 pm. It went from 77% to 84% in 10 minutes. Amps: ~1090 mA. Temp: 33°C

Screenshots 13 & 14: Gsam graphs

Observations: (This is in no way definitive and I do not claim it to be accurate as there can be inconsistensies due to various factors.)

-At over 39°C, charging slows down to ~500 mA

-Once below 38°C, at around 37.5°C, the charging picks up. ~2600 mA

-At the mid-way point when the battery is between 33% and 60%, the 5X seems to draw ~1800 mA even at low temperatures

-From about 65% to 85%, the draw is ~1000 mA with the temperatures well below the threshold

-Charging speed does not depend on the temperature alone. Even if the temperatures are low, actually using the device brings the charging rate to a crawl.

I'll do more low-temp tests when I have some free time, and also with a MXPE 25W charger to see if it'll perform better than USB C with the screen on.