Slugs Be Gone!

[ouzle]

OK, I've enjoyed a few days testing the Pyra now. I like lists so here you go...

The following worked perfectly for me without any trouble:
- charging when powered off (using an Anker IQ phone charger) ✓
- first boot ✓
- touch calibration (first attempt with one eye closed wasn't as good as with both eyes open!)✓
- external mouse (I find this easier and faster than using the nubs) ✓
- keyboard, felt awkward at first as there is a learning curve but after a few days practice I'm getting it ✓
- wifi setup using "advanced network configuration" in the MATE application list and network manager ✓
- MATE terminal (<ctrl>+<pyra>) ✓
- sudo apt update && sudo apt upgrade ✓
- debian repository is all there and working fine
- sound and video playback ("sudo apt install audacity vlc") - the speakers are great, much better than a Samsung phone say ✓
- 512GB SD Card in either slot ✓
- bluetooth headset or speaker ✓
- gl4es (for graphics acceleration etc) ✓
- multiple desktops with <ctrl> <alt> {1,2,3,4} is really natural with the key layout
- browser (Chromium from "apt install chromium". I've been using "gl4es chromium" but haven't thought much about it) ✓
- email (Thunderbird from "apt install thunderbird") ✓
- youtube (360p, maybe 480p) / bbc iplayer (works at higher res than youtube) / bbc radio ✓
- DBP packages, put one on the SD Card and the dbpd daemon mounts it and then its there in the menu ✓
- CPU governor and thermal throttle is working fine for me. I added the "CPU freq scaling monitor" to the panel to keep an eye on it). I see the bq27421_0-i2c-1-55 sensor consistently settles to 44C with no oscillation or overshoot. I ran a few stress tests using "stress-ng --matrix 2" and this ran fine at >1GHz for 2 hours at 20C ambient.

I had to tweak the following:
- I needed to add the "Notification Area" to the MATE panel to see the bluetooth; volume, network, and battery icons. The notification icons only work with the MATE high contrast themes (see menu -> "Appearance"). It looks like we need some more icons in the MATE pyra theme.

- Charging when powered up only works in bursts:
The easy fix is to take the battery out and put it in the fridge for 10mins or in the freezer for no more than 5mins! After this the charging continues when use for another 60mins. Its enough to get to full charge with short coffee cool off breaks.

- Battery slightly loose at contacts end - I saw the pyra power off a couple of times when I put it down too hard. I fixed this using a small piece of fluffy velcro on the underside of the battery at the contacts end.

- Risk of slugs getting in the pyra's ports: When I take the battery out after charging and stress testing, I notice there's a localized hot spot centered above the battery. I'm concerned this might attract Gastropods. Also, localized heat means there's an opportunity to shift it somewhere! I immediately reached for the "Slug Be Gone" tape. The external copper tape feels much warmer than the case plastic and I've not had any lock ups the last couple of days. Could making the internal label out of aluminium foil help?

I don't understand the meaning of the bq24297-i2c-1-6b temperature reading. Is this just a flag to trick the governor into throttling when the battery gets too warm? It only has two values of 22C or 60C.

 

[levi]

There in an internal bit of tape taking heat from the CPU to the type-A USB port. It's meant to get hot to dissipate heat from the CPU and stop it warming up the battery excessively. I'm not sure if then taking that heat back to all around the battery via copper tape is the best idea, but I'm not quite sure that's what you've done.

 

[ouzle]

The slug tape is an experiment to try to get more heat from the pyra to the outside world. The hottest surface I found, without taking the case off, is above the battery and the most effective way I've found to cool the pyra is to chill the battery. The top of the battery is always hotter than any external surface of the pyra so seems a good target for getting the heat out.
EDIT: It feels to me that the top of the battery is hotter than the usb port too. Its where I want to put a 'cold finger'

To get more heat out of the pyra I want to get a big area of the outside hot (heat loss [W] = heat transfer coefficent x surface area x temperature-difference).

 

[ible]

- Battery slightly loose at contacts end - I saw the pyra power off a couple of times when I put it down too hard. I fixed this using a small piece of fluffy velcro on the underside of the battery at the contacts end.

this helped me rescue a battery that i thought was dead. i added some electrical tape to the backside so that it would have a tighter connection against the the contacts, and it seems to be charging at least!

The external copper tape feels much warmer than the case plastic and I've not had any lock ups the last couple of days.

if you let it sit by itself for a while (idling), does it still lock up, or does the copper tape fix it?

 

[ouzle]

if you let it sit by itself for a while (idling), does it still lock up, or does the copper tape fix it?

ok, I'll test the idle stability, following your other thread, after my current build finishes. I'll try cold / hot with both discharging and charging. Should I stop MATE / panels for this test?

 

[ible]

either way, i get lockups after logging and letting it sit, but prolly also at the login screen

 

[ouzle]

either way, i get lockups after logging and letting it sit, but prolly also at the login screen

OK, so far no lockups for me.

I've done the following:
0) apt update && apt upgrade
1) discharge cycle at full CPU load (building with "make -j2")
2) idle charge cycle. The lid was closed, back-light and key leds at half. The pyra was on a solid worktop with the copper tape in contact with the worktop
At the finish T_ambient=18C, T_pyra=38C
3) Idle discharge in trouser pocket. The lid was closed (!), back-light and key leds off, base facing ambient.
After 2hours T_pyra=40C

I'm missing the pyra too much to carry on with the pocket discharge but I'll report if I see any hangs.

 

[ouzle]

I've had a look at the original copper strip from the SoC to the USB port. It comes with a nice copper heat-sink hat. I think the copper strip is supposed to be pushed down against the port when the case is on.

I didn't notice the USB the port getting warm so I've tried applying a bit of heat-sink compound between the copper strip and port. I also applied a small dot of cyanoacrylate glue to stop the end of the strip lifting up off the port as well as folding the copper tighter. The port is warming up a lot more now.

To make a bigger heat sink I decided to run a couple of legs of copper tape to the bottom surface of the Pyra. I opened up the little vent to pass the copper legs through. I removed the copper tape Id previously added above the battery and only kept the external copper that was under the ports. l also tried to improve the thermal insulation between the SoC and battery by adding a thin layer of insulating foam on top of the SoC.

I'm not sure this is having much benefit but its fun learning how the thermal design has been done.

 

[ible]

what sort of insulating foam? (link to buy?)

 

[ouzle]

The insulating foam is a very soft polyethylene foam, about 2mm thickness but it easily compresses. It holds the case plastic up a little further off the SoC.
Something like this ebay listing
or some "thermolam" polyester insulation.

Does the pyra have a battery temperature sensor? I dont want to prevent that from working if there is one?

 

[matzesu]

Yes there is a Batterie Temperatur Sensor, which is the thing that tells the Charging Ship when the Pyra Batterie gets i think over 40 degres celsius, and stops the charging, this is also the reason you have to take care of the remaining charge when you make tasks whit the Pyra that makes it quite warm, like rendering stuff or something..

 

[Letalis Sonus]

Does the pyra have a battery temperature sensor? I dont want to prevent that from working if there is one?

The temperature sensors are commonly within the battery package itself, that's why the battery has a 3rd contact.

 

[ouzle]

Here's the next iteration of my thermal hacks. I've not broke the Pyra yet!

This time I've fitted a cold finger to the bottom of the SoC. It is important to use Kapton tape to electrically isolate the copper finger from the SoC contacts! I also applied a layer of heatsink paste.

The pyra has ran at 1.5GHz for the last 2 hours at 44C, with power connected. Previously I got 1Ghz sustained.

The cold finger is a bent piece of copper strip 100 x 30 x 0.5mm. Its held in place by the case screw that goes through a drilled hole in the copper strip:

I made a notch in the side of the case:

Once the pyra is reassembled, I made an ergonomic heatsink out of a folded 0.25mm copper strip. The heatsink strip clips onto the cold finger and can be removed if not needed.

With a 70 x 30mm heatsink, the battery overheat didn't trigger when charging at high CPU load. When I pulled the heatsink strip off, the power button then started to flash a few seconds later. The heatsink temperature is about 43C so is very warm to touch, but not uncomfortably hot.

 

[Askarus]

Do you feel that miece of metal sticking out?
Is it comfortably to hold in your hands?

 

[ouzle]

It depends how big a heatsink I use. This 10mm height one still helps and is only noticeable because its hot. 30mm high sticks up so get in the way a bit. Ideally. it would be more embedded in the case but I don't really want to start sawing big holes yet.

 

[EvilDragon]

This is very interesting. If you find a way to improve the cooling without having such a big strip going outside the case and we can easily add that, I'd do that as improvement when assembling the next Pyras. Please continue your experiments.

The weird thing is though that I tried a metal plate between the battery and CPU board (where you now have the copper) and the result was that the heat didn't go to the heatsink anymore but to the metal plate - thus heating up the battery even more.

How thick is your copper tape?

 

[docbroke]

How thick is your copper tape?

The cold finger is a bent piece of copper strip 100 x 30 x 0.5mm.

 

[Askarus]

@ouzle
There is one idea I had years ago.
Put the copper tape between hinge and lid.
Thers is a little room between both and a small tape would fit there.
All you need to do is to lead the heat/metal up there.

 

[matzesu]

Well because i was quite exited from the fact that whe now have NUB Click and Youtube, i watched a lot Youtube yesterday evening on the Pyra, so i noticed it got slightly warm on the USB Port and the Ventholes on the underside, and also where the holes from the Speakers are..
Seems like whe arend on the Pandora anymore where you can use it on your snowy balcony whit a fur hat ^^.

Hopefully whit some optimacion on the Software Base, this thing dont need to drive full power just for youtube...

 

[ouzle]

This is very interesting. If you find a way to improve the cooling without having such a big strip going outside the case and we can easily add that, I'd do that as improvement when assembling the next Pyras. Please continue your experiments.

The weird thing is though that I tried a metal plate between the battery and CPU board (where you now have the copper) and the result was that the heat didn't go to the heatsink anymore but to the metal plate - thus heating up the battery even more.

How thick is your copper tape?

I wonder if the heat transfer to the battery is less on my Pyra because:
- my case is slightly lifted away from the cpu board and I've still got a foam pad on the battery.
- does the black plastic have a different thermal conductivity than the clear prototype cases?
- Have the production cases changed at all between the cpu and battery? The tolerances are pretty tight for that sheet of case plastic to stay flat. If the plastic between cpu and battery is not flat or has an air gap, then it could significantly reduce the heat transfer to the battery.
- the copper sheet has very low thermal resistance and good contact to the cpu board. What metal and dimensions did you try?