The Apple iPhone 5s was announced on September 10, 2013. Repair of this device is similar to the previous models, and requires screwdrivers and prying tools. Available as GSM or CDMA / 16, 32, or 64 GB / Silver, Gold, and Space Gray.

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Fast discharging, poor battery life - warm above Sim Tray


I'd like to ask You for Your help. I came across dead iPhone 5S, so I swapped battery for a new one and It came allive. But I ran into a problem and that's poor battery life. Any idea what could cause fast battery discharge? (With everything turned off, even SIM it takes only around 10h to be fully discharged.) Otherwise everything works, sim, bluetooth, wifi, sensors, camera everything OK. I looked for a possible answer the most probable would be the U2 ic chip, but I don't have anny other issues than just poor battery life. It connects to PC OK, I even tried to delete and restore It as a new Phone and downloaded a fresh SW from iTunes and installed it and it is OK, charging is also OK(Even from a dead battery.) I also noticed that the place above Sim tray is always a bit warm(barrely noticeable(NOT hot) when I compare It to my iPhone 5 - that one is stone cold at that place, when just sitting on the table.)

Any Idea what could it be?

Or could this make cheap bad new battery?

Is it normal that iPhone 5S is warm above Sim tray all the time compared to iPhone 5?

Answered! View the answer I have this problem too

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1 Answer

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Even though you can charge from a dead battery, there's still possibly a chance that it could be tristar chip issue(U2IC as it's commonly known)

I would try replacing your battery first but that probably won't be the issue.

Has the device been liquid damaged? Check for any corrosion, and check under the shields also, heat usually signifies that something is shorting, so check around the area that's warming up.

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I can't see any liquid damage. But could be some under the heatshield? I guess there is no easy way how to remove the huge heatshield in the back... maybe with a heatgun? Hmm..

Probably the best thing - remove heatshield... check for corrosion. If there is some clean with isopropylalcohol. If there is none... just to check the place where it heats exactly(can't now with heatshields.)

Or any better advice? :)

I am thankfull for any advice, opinion :)


Shields are removed with heat yes.

Here's a good video from Trents YouTube channel:


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