iPhone 12 battery draining fast

Hi all,


Trying to work out if I have a defective unit I need to send back or if there's a wider issue here. The iPhone 12 Pro is advertised as having a smaller battery than the iPhone 11 Pro so I expected to have slightly reduced battery life (which is fine as 11 Pro was excellent).


However I'm noticing that the iPhone 12 Pro is draining when idle with almost no background activity at a rate of 4% which is much faster than my previous iPhone 11 Pro, and to be honest a faster idle drain than I can actually remember from a new iPhone. First instinct was to disable Mobile data to see if it was a 5G thing, but I actually don't see any real difference from doing that (which makes sense as I've been on Wifi 98% of the time since I got it).


No matter what I try, it seems to be going down oddly quick. Not to an useable level or anything world ending, but I guess its sort of suspicious. I check the battery report, and it's not showing any real culprit, just a rapid decline for no clear reason.


If anyone can share their idle battery with either 12 or 12 Pro I'd really appreciate it.



[Re-Titled by Moderator]

iPhone 12 Pro, iOS 14

Posted on Oct 25, 2020 8:14 AM

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Question marked as Top-ranking reply

Posted on Jan 1, 2021 5:25 AM

After a couple days of experimenting.


Let me give you scenarios/examples with no regard to any other settings other than those mentioned being turned on or off.


iPhone 12 Pro running iOS 14.3


SIM card installed, WiFi on, Cellular On, Bluetooth in Standby (Turned off in CC to disable new connections, but still enabled)

Battery drops between 15 and 30% over an eight hour time frame while not being in use. (This was the case for a couple days, until I realized something was clearly wrong)


SIM card installed, WiFi off, Cellular off, Bluetooth standby same as before

Battery drops around 10% over the same time frame (Better, but still not satisfying)


Now get this!


SIM card taken out, Wifi on, Cellular off, Bluetooth same as before, I also turned Airplane Mode on for the sake of it

Draining between 1 and 3% , over the span of 8 hours.


I know, it seems absolutely silly to use an iPhone without a SIM card, but as long as this bug is not fixed taking out the Sim card might be your best option to prevent your battery from draining over night. Or you just simply keep it on a charger. Keeping the SIM and at least turning off WiFi and cellular or putting the device into airplane mode should make the battery drain a little less too.


Some other things you might want to switch off, if only to test for a couple days to see if battery life improves and slows the drain. Keep in mind, you can disable everything temporarily and don't have to worry about anything breaking. If something needs a certain thing enabled, iOS will most likely give you a prompt anyways. You can go back and enable everything again, but until a version of iOS 14.3.x or 14.4 is released that addresses the those kind of issues, it's the best and to be frank, the only thing you can do.


  • Location Services > System Services. Be bold and turn off EVERYTHING. Toggle the status bar icon (the switch on the very bottom) so when you slowly enable them one by one again, you can keep an eye on what triggers the location to update. With the status bar icon on, you can check and investigate closely how and when a certain service is updating. I found the Find my iPhone location feature updates like crazy.

System customization also updates in the background constantly ( if you turn it off, Dark Mode/ Appearance will still be able to work in sunset/sunrise mode, night mode however will work only when you put it on a custom schedule, and optimized battery charging will not work (even the option itself in the battery menu is enabled) if you have Significant Location and/or System Customization disabled).


  • Put Bluetooth into standby so it stops searching for new devices (Toggle it via Control Center so the icon becomes white.)


  • Turn off 'Ask to Join Networks' and set 'Auto-join Hotspot' to Never in Wi-Fi settings to stop the device from constantly checking for sources, notifying you and trying to connect to other routers.


I don't mention any of those things like turning off Background App refresh, dimming your display etc as those can be found in literary every 'iPhone battery savings' video or article.


It is clear that the issue can be pinpointed to the cellular modem, which can only be put into completely pause if there is no SIM card in the device. Airplane mode alone does not seem to fix the issue fully nor does turning off Cellular data help much if anything.



Similar questions

2,818 replies

Jan 26, 2021 5:31 AM in response to ticuor

I’ve been through that tedious effort and now have a replacement device which still has the same problem. Apple senior support wants me to run diagnostics again on this replacement device and is not willing to connect me to engineering when I tell all their iPhone 12 Pros are throwing issues. I declined saying i don’t want to be a lab rat and will find a workaround myself.

Jan 26, 2021 9:31 PM in response to sudharshanj25

Hello, your right ios 14.4 had not fixed the battery drain issue. I lose a lot of battery even with normal usage. With the kind of usage i have the phone should be able to last for about 2 days but thr fact that it at least lasts me a day is a really big thing. If apple is not interested in recognising the problem faced by its users, its time that we take some action. A company like apple is never expected to mess around with customers after charging 1000’s of dollars. Apple customer care, any moderators, if you are reading this and deleting this comment its of no use. Apple has already lost its market and theres no way its getting it back.

Jan 27, 2021 4:54 AM in response to ColinFromSussex

When I reported my issue with battery drain in December, I asked Apple operator, if he is aware about this issue widely discussed on Apple Forum. I sent also link to this thread. He said yes, they are aware. But it was just 1 operator. Nobody knows if any escalation was done.

So if there is no reaction until today via SW update, problem can be more difficult and perhaps in hardware, as it was already mentioned.

Jan 30, 2021 8:48 AM in response to Guim4uve

I use a 5W Apple charger still too. It is plenty fast imh. Doesn't heat up the device at all, or at least I have not noticed. Also I barely use it while it is charging. I stay away from wireless charging because of the heat created by it and I don't see the point of it. → Creates noticeably more heat and takes way longer??!? So I do not entirely get the point of it. I will however get (or build it myself) some sort of Magsafe mount that charges simultaneously for my car as this is really a convenient thing to have. I have one of those magnetic swivel mounts that has previously worked with a thin metal plate that is either put onto the back of the phone or between the case and the phone and I absolutely wouldn't want to miss having that. Built-in charging capability would make it perfect, and having it right next to an air vent it can cool the entire thing also. But as of yet, there is only the Belkin which is a total hit and miss because it lacks charging and anything else offered at this moment in time is kind of cheap and doesn't satisfy my need.


Fun Fact: The iPhone 12 Pro charging with a 5W brick takes exactly as long as charging an 2018 12,9inch iPad Pro with the included 18W adapter.


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iPhone 12 battery draining fast

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