[FP2] Metal case for better cooling / heat sink

Hey all,

I have met 2 other fairphoners in my life and we all 3 have the same problems, most important one being overheating.
I have already contacted FP on this issue but nothing really helped. One of my friends simply take off the metal back case when overheating with the risk of losing the battery .

My question to FP-team: could you please make a metal case? It can greatly help as a heat-sink and if the phone is attached to the car AC, it’s even more efficient.
(overheating happens mostly while using GPS + 3G)

My question to FP-community: has anybody tried to make a hole in the back case around the internal heat-sink (where “YOURS TO OPEN YOURS TO KEEP” is written) and fill this hole with some sort of heat conducting materials (e.g., you guessed it: metal).

Or any other solution before I go ahead and break my case?

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How long does it take to drain the battery?

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Not sure how this is related. The processor heat sink is overheating, not the battery.

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You can only make requests to the Fairphone team via the official support channels (e.g. https://fairphone.com/asksupport ). This forum is led by the community and no official support channel.

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I think it’s normal that the FP2 gets warm to hot when it’s actually used. We have with a smartphone a powerful computer in our hands and also a PC/laptop gets warm (and need a fan). You only have to worry if the FP2 gets warm when not in use.

I don’t think anybody has tried as it will void the warranty for his/her FP2.

Do we have negative effects with a metal casing like worse signal reception or increased electromagnetic radiation?
Another point of view: Will a metal casing have the same grip and will not feel “cold” in winter?


That is a diagnostic question. If your FP2 gets warm and you have an unusual high battery drain when not in use, something is wrong. Probably an app which actively runs in the background.


Thanks for your answer.

The FP gets so warm that it turns off sometimes (e.g. when not in direct contact with air conditioning when I use it as a GPS). That is a problem that my previous phone (Nexus 4) didn’t have.

Fairphone say other manufacturers using the same chip opted for a metal case because of this problem: https://fairphone.zendesk.com/hc/en-us/articles/213228026-My-Fairphone-2-gets-hot

You are right to say other problems could rise with a metal case. But the case doesn’t need to be full metal: only the area just above the chip. Because there is no air convection and only limited radiation for the heat-sink to cool down under the plastic case, this is why metal is important.

I didn’t know the warranty could be voided if I rework the case. Thanks for pointing that out.

To say it clear:

If your Smartphone needs a heatsink or a fan, then it is defective! Change it via warranty.

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I could experience the highest temperatures while using location service with Navmii or OsmAnd app and also charging.

There were no crashes, but I was worried.
This is definitely something that can get your phone to sweat, even without sun.

If your phone is rooted maybe I have a workaround for you:
Try the app “kernel adiutor” (last F-Droid version) and enable in menu kernel/temperature the SoC temp limit. Additionally you can enable in menu kernel/cpu the conservative cpu governor and turning down sync-threshold-freq and input-boost-freq.

If you are ill and the doctor says “go to bed and rest” then you are not less ill …

Forget the kernel-adiutor and the governor. I played a lot with those and nothing was better than the normal settings. Workaround: that could be the advice “shutdown your phone and everything is cool” which is natually shit.

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I would only suggest the workaround if someone don’t want to send the phone to support for exchanging under warranty for whatever reason. My friend have one FP2 which is now usable without crashes after applying this workaround and remounted the back cover.

I also wondered about the heat in my phone and how to better/faster remove the heat from the CPU area.
I don’t want to throttle the CPU to reduce heat and I don’t think that I have a broken phone as Spielmops suggested.
All I want to know is: Can I or somebody else mod the phone so that the heat gets away faster from where it is generated. I considered removing the whole plastic thing with the inscription “YOURS TO OPEN…” because it tells me to do so. I don’t care about warranty because that’s only money. But I don’t want to destroy the phone, because that would be resources wasted.

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How long lasts the battery of your phone?

I though I made it clear that I don’t want to discuss whether my phone is defective or not.
Anyway, I guess you mean: How long lasts the battery of your phone if you don’t use your phone? I cannot answer this question because there has never been a day without heavy usage.
So here my question again: Can I ore somebody else mod the phone so that the heat gets away faster from where it is generated during heavy CPU usage.

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I have asked the Fairphone support if they could publish the CAD file of the back cover. With today 3D printers, we can build silicon pieces (the soft thing holding the back cover), hard plastic and even metal.
If they answer positively, I will modify it to include a metal piece.

Otherwise we’ll need to design it from scratch. If there are mechanical engineering reading this thing, I believe we could use your help.



No, what is interesting for me: how long lasts the battery with your normal usage?

I would be careful with a metal case because it will have an effect on the radio signal. Some possible effects:

  • Shielding (faraday cage effect).
  • Reflection: You, but not the mobile tower get the microwaves.
  • Reduced performance because of de-tuning of internal antenna.
  • Radio signal travels to other parts of the phone and causes trouble.

Thanks mate, that wouldn’t explain why other phone manufacturers, who might have tons of EM engineers, offer metal back covers.
Besides, I’m just offering to make a piece of metal of the same size as the already existing heat sink.

I think your question leads to nothing. What is normal usage? Weekday usage? Weekend usage? Recreation usage? I always charge the battery to the fullest before I leave, so I could not answer your question even if we define normal usage.

I think your answer is directed to wli but he/she did not talk about a full metal case, only a metal piece. I don’t see how adding a small heat sink at the back of the phone could cause the problems you mentioned.