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Now that I'm happy that: the battery charging cuts out when the actual battery temperature >39C (measured using a pyrometer) I have thermally separated the CPU from the battery with an air gap My cold-finger and heat-sink on the back of the CPU is working well (it gets hot when the battery...

I wonder what this comment in the wwan-on script means? Maybe summons yomagn:tho in the form of a flaming pyra battery? # PHS8 might be in at^sdata=3/4/5 mode (NEVER NEVER SWITCH TO at^sdata=2 or you are in big trouble!)"

Does it come back when you run "sudo /usr/share/pyra/scripts/letux/wwan-on" ? EDIT: Added hyperlink

With the battery back in, I've not yet managed to trigger the hot battery fault when charging at full CPU load. So it looks like when I first received the Pyra, the hot trigger must have been less than 39C. The thermal gap I added between CPU and battery might be working and/or the hot trigger...

I've made some more measurements now. I'm not sure I understand the results but I'm now happy that I've not got a Pyra-technic... Anyway, without R710 installed, my pyra won't charge when the battery is hotter than 39C (ok), or below -15C (that's too cold). To measure this, I left the...

I don't think I've been near R2001. With metal to metal contacts its normally all or nothing, or shorted to something else. Static, heat and overvoltages can cause a CMOS chip Latch-up. That could cause another current path to be wired in where it isn't expected. I'm not a professional, so...

There's a chance I've shorted a pin on the BQ24297 as I reflow soldered it. I've not had much practice judging exactly how much solder to apply. If I find the Pyra is not working I might try to resolder it but its all working right now. I've still got one spare chip too. I plan to check that...

OK, its not so difficult to choose the resistor to give a hot battery charging cut-off. I've confirmed that the battery has a standard "103AT NTC" 10K thermistor by measuring the resistance as the battery cooled for a few minutes. This means that the example values given on page 26 of the...

If you want to send one command directly, you can use "wwan-on" to find the modem's USB serial port, e.g.: user@pyra:~> sudo /usr/share/pyra/scripts/letux/wwan-on /dev/ttyACM1 Then pipe your AT command to "femtocom" with the serial port as the argument. There's a sleep included when piping the...

I do not plan to leave the Pyra charging unattended with the hot cut-off by-passed! My plan is to calculate a different resistance value for R710 to set the battery hot cutoff to something more practical. I'll try to make sense of the formula in section "9.3.3.3 Thermistor Qualification" of...

Not today, no. Indoor air temp here is only 18C and cpu load was only browsing / scripting. I let the pyra fast charge (2A) on a desk from 40% to full whilst powered up. Insulation is still installed between cpu and battery. The battery felt like slightly above ambient, I guess 30C.

It charges much better without the R710 battery thermal regulation resistor installed, muhahah! I won't hold you responsible for my own pyromania.

I wanted to understand how to talk to the Pyra's modem so I started by studying how hns does it in the wwan-status script. I've tidied this up a bit to give more description in its output and reduced the delay a bit so it runs faster. The original script is from the letux kernel tree and is...

Did you see hns' kernel discussion from 2018 about how over-voltage can cause the modem to power off? Keep an eye on the VSYS voltage with the /usr/share/pyra/letux/charger script. If VSYS exceeds 4.2V then the previous kernel fix has stopped working. Was your battery fully charged when the...

I've done a few more tests (with motherboard removed and CPU disconnected): * R710 is definately 31K in isolation * With R710 removed, the resistance on the R710 board contacts is 37K5.

Apologies, the resistor value change was after putting everything back together and running for a while. I shutdown, removed the battery and measured the resistance off the battery contacts on the motherboard (not the battery). I saw 16K but it was smoothly changing and increased gradually to...

The battery thermistor BTEMP also goes to the CPU module, pin P2001:38. The schematic shows another potential divider (R2001 and R2002, 100K + 33k) at the CPU module. This is in parallel with R710 but should be significantly higher resistance. At BQ24297: BTEMP to R710 to GND should be 31k6...

@hns @EvilDragon I've tried to measure the thermistor resistors on the BQ24297 battery manager chip on my board. The board was removed with no battery or CPU installed. On my board R710 (TS to GND) reads 18K (with the chip in place) but the schematic says 31k6? This is the resistance from...

Now updated to read registers from/sys/class/power_supply/bq24297/device/registers or /dev/i2c-1 if the -i argument is given

Ok, I'll update bqdump24297 and bqdump274 to take the values from /sys/.../registers. That way it won't need sudo to work.