When my Tachyon is plugged and the battery is charging the under-side components becomes extremely hot (I’m not exactly sure which components are below vs which are above the PCB). They are not exactly scalding to the touch, but it’s close.
Is it normal?
Also the battery capacity (both in the desktop widget or as shown by the /sys/class/power_supply/battery/capacity file) is very imprecise. Basically I see 43%, 60% or something above 90%. But nothing in between.
If this is expected, maybe the capacity should be given with a smaller scale (like 1 to 5)?
Is this using the single cell battery that we shipped with Tachyon or the 3 cell battery? This sounds like the battery SoC is not readying correctly and the module getting hot is very likely the thermal management not running - love to know how you got into this state as this subsystem had a lot of fingers on it and I think this would be the first I've heard of this issue!
If you can provide a brief description of your setup and use case, that would be amazing. If you are ok, I'll share a tool that can provide a 'log dump' as a ZIP file that you can run and then share with us (with no personal info in it etc..!).
Yes, this happened while charging the 3-cell battery (from the kickstarter), plugged into a USB-C hub with desktop mode active. I indeed did not notice that with the 1-cell battery.
This also happens in headless mode (that is, running the desktop version of the OS, but with the device connected into a 65W USB-C charger and not connected to a screen). The battery itself is quite cool (reported at 30°), but the tachyon underside is super hot (it’s possible to touch it, but barely, I’m not sure what temp that is on a scientific scale...).
I did not observe that same high temperature when charging the 1-cell battery.
The sensors command does not show much except that the battery is charging at 2.98 amp. Going through all thermal zones in /sys/class, there is one that has a higher temp than the other with type pm7250b_tz and temp being 79°.
As a side note, it took me a little less than 3 days of the device continuously running to deplete the 3-cell battery (wifi + cellular on, but almost no activity). This is reasonable but maybe not huge. One thing of note is that just 2 hours before the device switched itself off, it was still showing a battery capacity of 56% (according to /sys/class/power_supply/battery/capacity). When I rebooted it up after it shut down, the capacity was shown as 0%.
Maybe the most important symptom is that the Tachyon feels extremely sluggish while charging (e.g. lag with the characters echoing over SSH, poor performance of a remote vscode instance, etc.).
I couldn’t find any direct indication that the CPUs are throttled, but the cpufreq-info util consistently shows all the core at their lowest frequency.
If I unplug the device the pm7250b_tz temperature starts to lower, the device feels more reactive and the cpufreq-info command will in general show 2 of the small cores running at 1.96 GHz instead of having them all at 691 GHz.
So it seems that the CPU is being throttled when the device is charging.