iPhone 12 battery draining fast

same here. Dual sim excessive discharge. I suggest to call Apple support. We need more people reposting the issue. They are currently investigating my issue. At least they are taking it seriously as it got escalated to senior staff.

This is the same with my iPhone 12 pro. When using both line battery drain in standby is about 10% - 15% per hour. The phone barely lasts a day. Battery life is like my iPhone SE 2020. When I turn off the second line the battery drain stops. I had the same setup on all my prior iPhones as iPhone 11 Pro and pro Max with no issues. Here you can see my results while playing with second line on and off. Not being able to use the second line or having it to turn off most of the times is no solution.

It looks like there are actually two problems, one has to do with dual sim and the other only appears while using one sim. I'm using one sim and after I replaced my iPhone 12 the drain was "only" 12% last night (down from 30%). It's still way too much. I will continue to activate airplane mode, which leads to 3-4% drain overnight. I'm not sure if Apple did some behind the scenes fixing or if it's actually an hardware issue.

I think the widgets might not be related to this issue because the discharge curve of my iPhone 12 is back to normal while I didn't kill any widgets.

Odiebla wrote:

Agree. Disabling the second SIM definitely makes things better, but the discharge curve is still not what I'm expecting. Last night I've killed all my widgets, Safari tabs and closed all 'open' apps (swiping them up) and then my fully charged 12Pro (single SIM) stayed on 100% for over 4 (!) hours, then slowly started to discharge at about 1% per hour. Last night I then enabled the second SIM but assured that all Apps and Safari tabs are closed and the discharge rate increased, but was still more or less 'acceptable'.

So I'm going to focus my own investigation on the widgets, open apps and open tabs. Potentially one of these prevents the handset from entering idle-mode. So indeed, it seems there are multiple issues.

1. When I use dual sims(China Mobile and China Unicom), if I set China Unicom as the cellular data sim, the battery drains 20%-30% over night. But if I set China Mobile as the cellular data sim, the discharge curve of the battery is back to normal.
2. When I use single sim(China Unicom), the discharge curve of the battery is still good.

The above results indicate that it is a potential bug in iOS.

In the evening, completely ruined the phone to zero that it would turn off, then put on 1A charging, from 3 am to 9 am result 100% ! All services are included

and WiFi, e-sim, widgets are off ! Is the problem with widgets ? Try it the same way !

Yes, I just got something in my mind. There are 2 possibilities, which are very likely:

1. There are 2 4G/5G cell towers, which are on similar distance from the phone. If there is actual problem with locking to a specific tower, it constantly changes the tower which leads to battery drain.

2. There isn't a 4G/5G cell tower in close range, which also can lead to battery drain.

If it is the first one, I believe that it can be fixed by a software update. For the second one - I'm not sure. We need someone from Apple to acknowledge the issue, which is 100% there.

I couldn’t agree more !

OK, at 7 this morning I did a full DFU restore on my 12 mini and set it up as a new phone with nothing from my old backup. I have installed 10 or 12 applications from scratch, all of which ran quite happily on my SE and did not cause power drain. And I am still, 4 hours later, seeing the same rate of power drain as previously.

I'm giving up on this phone - mine is going back for a refund. I'm starting to think that those of us who are seeing this problem have modem chips which have a hardware fault; I've now tried everything I can think of to fix this through software. If Apple address this in future, I might buy another 12 mini in 6 months time, when they have fixed the bugs, but for now, this is not fit for purpose.

Now that's very interesting. I'd wondered if it might actually be that some SIMs have a compatibility problem with the modem; your post suggests that this problem is network-specific, so it may be that some networks need to update their profiles to work properly with the modem in the 12. I had considered asking O2 for a replacement SIM or an eSIM to see if that made any difference - maybe I should do that before I give up and give the phone back...

This is interesting and also something I had considered. Now which network drains and which doesn’t. The reason why I have no problems with my Telekom eSIM (EE is part owned by Telekom) while adding the Vodafone Italia sim the drain starts. So either a dual sim problem or perhaps really a network problem? It might be the most logical explanation other then a firmware bug.

I’m sure though that turning off data will jot make a difference. It’s has nothing to do with data, it’s the connection to cell operator itself even without data. I tried this by turning off roaming for my Vodafone Italia sim with no change in battery drain.

Yes, your point nr. 3 is solving the problem, as the issue is with the new modem on 4G/5G networks.

The challenge is, that most of the service providers who offer 5G, have this option removed, so users can only choose between 4G / 5G / 5G Auto.

On top of it, using a smartphone on 3G at the end of 2020 is not an acceptable compromise, even if wifi can compensate for the speed.

this is an Apple forum, be sure that Apple knows about the problem.

They will not react yet, because first they need to analyse the problem and figure out possible solutions: is it software related? they will work on it for the next release. Is it hardware related? Can it be fixed without replacement? Do they need a callback? How many people even recognize it?

Sometimes admitting a mistake costs more than handling the issues one by one - if they react ANYTHING now, it will be leaked and many people will choose to avoid iPhone. They can't allow that.

My personal solution is that I'm giving back this 12 mini and ordered another one - and will keep doing this as long as I find a properly working one. The good ones exist too, this issue may be an early production batch problem - at least I hope so.

I did a test yesterday. I had my phone 100% at 10am. I turned it on airplane mode then didnt use it for 24 hours other than just checking the battery. It drained to 84% by the next day. That is much better than what i had been getting previously which would have been at least 30%. This does suggest it is down to the network.

I then tried a 30 minute youtube video. This drained 4% with airplane mode on and also 4% with airplane mode off. No difference.

I guess this proves that it's only when idle this issue seems to occur and not really impacting when the phone is in use. Not sure if this is helpful or not. I'm going to turn everything back on now and just enjoy the phone until someone comes up with a fix. I will put it in airplane mode overnight each night.

I live in Russia, a YOTA operator. At night, my iPhone 12 mini is drained by 17-21%. Today I put it in flight mode for the night but left WI-FI enabled.the phone was 3% dead. At work, for some reason, it discharges more slowly

I think i might have figured out the root cause. When buying new phones, usually it is advised to charge the phone full for the first 12 hours without turning it off. However, Apple's software stops charging the phone beyond a certain percentage to extend battery's life. I think this might be the reason the battery performs poorly during the initial phase. So i would advise you do this.

1) Turn off the machine learning optimization of battery

2) Charge the phone for 12 hours. Intermittenly, plug out and plug in back deliberately if needed

3) Do the observation the next night.

TURN ON EVERYTHING. Wifi, bluetooth, 4g/5g, background app refresh etc., This is to ensure that the problem is isolated just to warm up the battery to full.

Please try this. I had earlier posted a picture with a worse battery status drain. But now my iPhone is back to normal. I did not do any software update. I just kept charging and charging for 12 hours.