What are safe temperatures? Building a thermal-engine.conf?

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SilentDevGuy

Senior Member
  • Feb 10, 2021
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    As the title states, what are safe temperatures for modern phones with heat pipes, fans, etc?

    My current daily driver a Snapdragon 855+ consistently hits 60-75c CPU temps whilst gaming or heavy web browsing, however despite this my battery never exceeds 45c.

    Is this safe for the phone in the long run?

    Are modern phones keeping the nand far from the cpu?(main heat source)

    Reason I ask is because nands deteriorate rapidly starting at 48c+..

    There is also NO documentation whatsoever that I can locate on hardware shutoff temperatures for modern phone socs..

    Any insight at all would be great.

    As a side note what do you put in a thermal engine if you wanted it to underclock at 55c until 40c?
     

    ineedroot69

    Senior Member
  • Nov 13, 2019
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    ctemp is cpu temp
    btemp is battery temp

    completely stand by 33celcius
    Screenshot_20210312-102643.png


    while mid way of CPU stress test
    Screenshot_20210312-103141.png


    highest recorded CPU temp is 38celcius also i just notice i need to change my CPU governor only 4 are doing heavy work hmmn 🤔 okay how da fvck do i change my CPU governor🙃
     

    blackhawk

    Senior Member
  • Jun 23, 2020
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    105°F is getting too warm for a phone battery... and you're going above that.
    While Li's can operate up to 150°F, for a phone a more conservative limit of 102°F is best.

    In direct sunlight with those temperatures you could fry a display before the thermal shutdown kicked in.
     

    ineedroot69

    Senior Member
  • Nov 13, 2019
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    105°F is getting too warm for a phone battery... and you're going above that.
    While Li's can operate up to 150°F, for a phone a more conservative limit of 102°F is best.

    In direct sunlight with those temperatures you could fry a display before the thermal shutdown kicked in.
    okay i was about to change my CPU governor but after i read what you had said i provably stick to the default then
     

    blackhawk

    Senior Member
  • Jun 23, 2020
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    okay i was about to change my CPU governor but after i read what you had said i provably stick to the default then
    I would. I fried a stock Android display like that with the conservative stock settings🤣
    It's not just the cpu you that can be damaged.
    You need to take into account temperature hysteresis as well and leave a decent safety margin.
     
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    SilentDevGuy

    Senior Member
  • Feb 10, 2021
    71
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    I would. I fried a stock Android display like that with the conservative stock settings🤣
    It's not just the cpu you that can be damaged.
    You need to take into account temperature hysteresis as well and leave a decent safety margin.
    Interesting information you provided, what temps would a display fry at? One of my phones is capable of running the cpu to 75c (yes i know thats extreme, it was a stress test) for over half an hour while the remaining components never exceeded 45c according to available sensors
    How would you build a thermal engine?
     

    blackhawk

    Senior Member
  • Jun 23, 2020
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    Interesting information you provided, what temps would a display fry at? One of my phones is capable of running the cpu to 75c (yes i know thats extreme, it was a stress test) for over half an hour while the remaining components never exceeded 45c according to available sensors
    How would you build a thermal engine?

    While the phone has a lot of temperature sensors in the display there are thousands of mosfets as wells as the OLEDs.
    No way to monitor all those microscopic P/N junctions.
    Not much heat sinking/porting other than the glass of the display it's self.
    Glass is not an efficient thermal conductor... the back panel if ceramic maybe better. Most cases also help trap heat.

    Temperatures that pose no issue for a freestanding mobo/cpu can quickly become one in a small sealed unit with densely packed components.
    You may be able to get away with 200°F temps sometimes but it will take little to tip the balance. It can happen so fast that even auto shutdown will be useless. Weakest link... the last to be seen and the first to go.

    Using a damp microfiber cloth can help cool it down a lot especially with dry moving air.
     

    SilentDevGuy

    Senior Member
  • Feb 10, 2021
    71
    21
    While the phone has a lot of temperature sensors in the display there are thousands of mosfets as wells as the OLEDs.
    No way to monitor all those microscopic P/N junctions.
    Not much heat sinking/porting other than the glass of the display it's self.
    Glass is not an efficient thermal conductor... the back panel if ceramic maybe better. Most cases also help trap heat.

    Temperatures that pose no issue for a freestanding mobo/cpu can quickly become one in a small sealed unit with densely packed components.
    You may be able to get away with 200°F temps sometimes but it will take little to tip the balance. It can happen so fast that even auto shutdown will be useless. Weakest link... the last to be seen and the first to go.

    Using a damp microfiber cloth can help cool it down a lot especially with dry moving air.
    The phone in question contains a cooling fan and vapor chamber, the components genuinely do not reach the cpus temp using a laser thermometer, however I agree that the temperature isnt safe and thus brings me to my original question, how would you build a thermal engine? Everyone seems to agree with me that the temps arent safe. Also the phone has a full metal body to cool faster then a glass sandwhich, and I typically do not use a case but the one I have is designed for cooling and doesnt create a general heat increase
     

    blackhawk

    Senior Member
  • Jun 23, 2020
    3,339
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    The phone in question contains a cooling fan and vapor chamber, the components genuinely do not reach the cpus temp using a laser thermometer, however I agree that the temperature isnt safe and thus brings me to my original question, how would you build a thermal engine? Everyone seems to agree with me that the temps arent safe. Also the phone has a full metal body to cool faster then a glass sandwhich, and I typically do not use a case but the one I have is designed for cooling and doesnt create a general heat increase

    If you were sinking enough of the heat thermal throttling be no issue... inadequate heat sinking is the issue.
    A full imersion liquid cooled phone be more effective... no more hot spots and plenty of potential btu sinking capacity.
     

    SilentDevGuy

    Senior Member
  • Feb 10, 2021
    71
    21
    If you were sinking enough of the heat thermal throttling be no issue... inadequate heat sinking is the issue.
    A full imersion liquid cooled phone be more effective... no more hot spots and plenty of potential btu sinking capacity.
    A slight misunderstanding, my device NEVER thermal throttles, it always releases the heat perfectly fine. My question is in regards to ME wanting to throttle my phone, not stop it.
     

    blackhawk

    Senior Member
  • Jun 23, 2020
    3,339
    829
    A slight misunderstanding, my device NEVER thermal throttles, it always releases the heat perfectly fine. My question is in regards to ME wanting to throttle my phone, not stop it.
    Because it's rooted you need to modify it; as it is now it just keep running no matter how hot it gets?
    That's a rather serious rom issue.
    I have no clue how to do that with Androids... someone here probably does.
    You should probably use the stock profile as they most likely use many of the temp sensors readouts in conjunction for throttling.
     

    SilentDevGuy

    Senior Member
  • Feb 10, 2021
    71
    21
    Because it's rooted you need to modify it; as it is now it just keep running no matter how hot it gets?
    That's a rather serious rom issue.
    I have no clue how to do that with Androids... someone here probably does.
    You should probably use the stock profile as they most likely use many of the temp sensors readouts in conjunction for throttling.
    On android the thermal engine is built around the same sensors and is actually what the rom uses, i see where the misunderstanding was now. To get you up to speed on all android roms the throttling is handled by the thermal engine which is modifiable by the end user, I personally am only aware of about 50% of the parameters and was seeking someone with more knowledge to teach me on how to build it from scratch. In regards to the "no matter how hot it gets", to clarify my phone has not physically reached shutdown temperatures and/or throttling because it is CAPABLE of releasing the heat WHILST RETAINING high cpu freqs/usage. The only way I can force a throttle is to apply external heat, the phone itselfs has a cooling system, that is cooling past what its cpu is capable of creating in heat.
     

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      okay i was about to change my CPU governor but after i read what you had said i provably stick to the default then
      I would. I fried a stock Android display like that with the conservative stock settings🤣
      It's not just the cpu you that can be damaged.
      You need to take into account temperature hysteresis as well and leave a decent safety margin.
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