iPhone 12 battery draining fast

Do you use DUAL SIM? I'm asking because my iPhone 12 Pro does the same but only when the second SIM is active. If I deactivate the second line the battery consumption is back to normal. Would be nice to know. I have a support call from an Apple engineer coming in later today, let's see what he's got to contribute.

Absolutely right! Today’s night my phone lost only 1% per night(8h), but that happened to me only with the airplane mode ON. The phone stopped heating while browsing social network, safari etc. I’m absolutely sure that the problem of heating and drain is related to a new x55 Qualcomm modem, and I do think this is a software issue. Hope apple will fix this.

Proof of the heating problem is caused by an X55 is the fact from too many users on a Russian 4pda forum, when all of us switched into the AirplaneMode, all of the games were stopped losing frames and the throttling is near to be gone

How did you switch to 3G? I can only switch from 5G to LTE/4G, while latter is the only option available when using DUAL SIM and definitely makes no difference on mine. Still the same drain when using dual sim. When using only one line it's fine, whether it's in 5G Auto or LTE makes no difference, probably because it's mostly in LTE anyways. Also an important note this all happens while on WIFI too. No difference if using cellular data or WIFI.

I have the same issue with my iPhone 12, been a week since I found out that the battery drains 22-29 percent on idle each night. Really frustrating. I took it to the Genius Bar and the engineers there are not able to provide any workable solutions (background refresh off, location service while using or off, swip up and close all opened apps...nothing I dont know), at last their supervisor said it might be an issue with corrupted data and if it is determined to be the true cause, I will have to reset my phone and transfer my data bit by bit and hopefully the "corrupted part" is not transferred. The supervisor also said he read some of the logs and found my Photos app reads and analyse my photos at night and that might be one of the causes too...(wtf..). They did offer the option of a new service unit but they also told me chances are it won't solve the problem. Geez this is driving me crazy.

I've updated my iphone to iOS 14.2 and problem still present. After that i have called to apple support, they made remote diagnostics and told me that iPhone works fine lol. Their recommendation - "go to the service center and give your phone to diagnostics and repair". Nonsense.

Yes, a lot of iPhone users in China report that they have this issue too. Actually I have tried to contact with Apple support engineer. However, they just told me that my device looks good according to their test report and advised me to reset my phone or disable background refresh... Nothing works! I am so disappointed that there are a lot of people complaining this issue but what did Apple do? Just tell us a deadline when this issue will be solved, arrogant Apple!

I also called yesterday, (though I’m still at 14.1) they did diagnostic too, found nothing this way either.

I have asked a refund since I still had my 11 pro, and even not had yet transfer my SIM in the new 12 pro, and frankly, my 11 pro still do the job. Battery is still 100% optimal. So why keep a phone that the battery will have so much cycle done until they fix the problem.

I just hope that they will find the problem with everyone returning their device, and fix it soon, so I can buy another one. I may be tempted by the Max though... but yet I will wait this time to see if the problem exists on them too, and wireless charging is compatible with vertical charger, since I also had this slow/not charging problem with mine. Too much problem. I may skip 12 too...

I also have been experiencing the same issue, typically drains by around 20% overnight with no clear culprit of an app. I was told to turn off Background App Refresh by an Apple Support chat handler which seems to have negligently improved the situation but this clearly is not what is causing the battery drain.

Unfortunately the situation has indeed not improved with 14.2. I strongly encourage everyone to submit feedback to Apple. The best way to do this is by using the Feedback app. You can enable this by enrolling in the beta program and install a beta profile on your phone. After rebooting you will have a new 'feedback' app (you do NOT need to actually install a beta!) and here you can create feedback. Answer all questions, include screenshots of the drain and include diagnostic files for analysis by Apple.

I'm pretty convinced there is a bug in the new radio/DSDS (dual SIM, dual Standby) driver/firmware that is triggered when two SIMs are enabled, it seems that the phone then continuously burns a lot of cpu time and eats away battery at a linear rate without any justification for that.

My 12 pro drains super fast. I am connected to wifi and blue tooth speaker. I have had the phone for a week and all was good til 2 days ago. Phone drained in no time. Support said it's my blue tooth speaker. Not sure about that. Blue tooth does not use any appreciable power. My iphone X ran all day with the speaker and used maybe 30%.

I just realized that only "dual sim" iPhone 12s are suffering from the battery drain. Even if only one sim is inserted, battery drains still. My friend's 12 Pro is regular single sim model and his phone's battery standby is amazing. That explains why my battery doesn't drain when airplane mode is on. But what causes my battery to drain if there's only one sim? Perplexing

You are mistaken. first of all, now all models dual-sim: one regular card and one esim or two regular cards. Second: I have this problem on sim+esim model, moreover, when two cards are active, when any one card active - in any cases when 4G is active i have battery drain.

i will make one experiment - my friend have iphone12 and no problems with battery drain, and i will test my phone with sim-card of his operator. may be this problem are specific to some kinds of 4G networks, and to some kinds are not.

Each active account maintains contact with its cell tower every few minutes, saying “here I am”. It does that so the network knows where you are when a call comes in for you. This “registration” is very expensive in terms of energy, as it is done at full power to assure a connection. If you have 2 active lines it will twice as much energy as one line.

no! wifi enabled, 4G sim enabled, cellular data disabled. Battery drain is about 4% in a hour. When i disable sim or switch to 3G drain is stopped - about 0.5% in a hour. When i disable both wifi and cellular data but continue connection to cellular network - drain still continues. Battery drain does not depends to wifi or mobile data enabled or not, only to sim card connection to 4g network.