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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 Best reply

Posted on Nov 2, 2020 7:46 AM

That is simply not true, I'm an engineer working in the mobile telecom industry and the discharge rate currently seen on my iPhone12 is a faulty curve. I feel no point in debating that, as this is just a simple scientific observation that I already cross-referenced with a known-to-be-good situation both both the iPhone11 and the iPhone12 under normal conditions.


Please check both curves, on the top you can see a drain, regardless of any handset usage during day OR night AND despite low-power mode. Any engineer can tell you this is abnormal behaviour. On the bottom you will see a 'normal' discharge curve, where you can clearly see it's not a straight line down the hill but is depending on usage etc. Note: both are made on my iPhone12Pro, the bottom one differs in 1) no second 5G SIM (in 4G mode only) enabled and 2) low data mode mode enabled on the first primary eSIM. I'm currently testing to see what actually caused the difference in discharging by disabling low data mode on the first eSIM. If the discharge rate continues to be 'normal' then there is a clear indication that enabling the second SIM caused abnormal behaviour. That is not 'me too', that is just a normal observation. If you think it's normal then you're perfectly entitled to that opinion, but then there is little you can contribute in this topic I'm afraid. It is my personal and professional opinion that this is not normal and considering the fact that Apple has accepted bug reports, fixed the issue and contributed them to me in the release notes I think I'm still doing a useful job here :-)


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2,818 replies

Nov 25, 2020 2:02 AM in response to hdoerner

Tonight the issue hit me again after a few good days. I used Shazam in the early evening and stopped using it. As you can see in the screenshot then suddenly during the night at 23:00 the battery started draining again, the only process causing this was Shazam for 100% or the time. What is particularly odd is that it stopped exactly around 08:00 when the iPhone fired it's alarm and took itself out of 'bedtime' and DND mode. Note: Shazam is configured not to allow background refresh and it was not 'killed' by swiping up. I had exactly the same issue a week ago when Siri was responsible for 100% of my background activity and also this stopped when the bedtime/DND mode was turned off.

Nov 25, 2020 9:22 AM in response to Master26A

I follow this problem from the beginning and I had the same problem with my iPhone 12 pro. The batterie lost 30% over night. Few days ago I did a network reset. Until this moment my batterie lasts 2 days with normal usage. Please everybody try it. There not much to loose.

Nov 25, 2020 7:24 PM in response to askar_berlin

askar_berlin wrote:

I noticed that my iPhone didnt loose a single percent of battery power in about two hours ....

After loading my iPhone for some hours it takes about two hours before the draining begins. Thereafter the drain is constant. Loading for a shoort time does not have the effect. Did you load your iphone before you noticed that?



Nov 26, 2020 1:58 PM in response to Insanejojo

So after two consecutive days/nights of observing my new 12 Pro Max, it’s been doing perfectly good. Here’s a graph of the battery performance. Yesterday as you can see, I fully charged it 1:09PM and I didn’t use it that much just to observe the battery on idle. Just some few texts here and there. I just woke up now at 5:40AM and it’s at 95%. Is it safe to conclude now that my new unit doesn’t have the battery drain issue?

Nov 27, 2020 4:46 AM in response to Master26A

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.


Nov 28, 2020 9:39 AM in response to Master26A

Hi, I’m having the same battery drain when idle with no active apps issue most of the time since I got my iPhone 12 Pro. I believe, I went through all possible troubleshooting steps.


Initially, I restored my phone from encrypted backup because I didn’t want to go through the hassle of setting up everything from scratch. I ended up with battery drain. After chatting with Apple Support, they found no issue with my battery after running diagnostics. So we went through my settings, like location services, background refresh etc. and they all looked good because I manage those very tightly. As a result, they recommended to erase the phone and setup as new, which I did. That didn’t help. After that Apple Support had no idea what else to suggest except using low power mode, which still didn’t help much...


I should note that I’m using both sims, eSim being the main one for calls and data. 5G is turned off completely.


The issue however sometimes resolves on its own and the battery is excellent throughout the whole day, without me making any changes whatsoever. So this very inconsistent for me and it makes any attempts to A/B test pointless...


Many times I thought my change resolved the issue until it came back the next day out of nowhere.

But I did notice that using only one line seems to help a bit. I’ll keep my settings unchanged for few days in order to observe this.


And as many of you mentioned, airplane mode completely resolves battery drain for me too.


Nov 30, 2020 11:48 PM in response to Master26A

my iphone 12 is experiencing battery drain on idle state , even i did all battery saving tips. Its actually work for usage time about 6hrs on 100% battery without gaming. So, i was complaint & give back new one . unfortunately , the new one also has similar problem. I think that all 12 iphone has fucking battery drain issue , especially in idle state.

Dec 2, 2020 5:58 PM in response to zanlyons

I was wrong, partially. The issue is back at least in dual sim mode. When using only one sim, either Telekom eSIM or WindTre physical sim (in roaming o2 DE) no excessive battery drain. When using both lines battery drain, only in idle circa 12% per hour. In dual SIM mode the iPhone 12 Pro doesn’t last a full day. Battery is on par with iPhone SE 2020, probably a bit worse.

Pas soon as I turn off one of the lines the battery drain stops. See the screenshot I turned off the second line roughly around 9pm.

for me, I know not for everybody here, the problem is clearly related to DSDS mode that the new modem can’t handle correctly.

If there are many others here with the same issue just with DSDS I suggest to start a new discussion to get the problem isolated from the other problems here.

iPhone 12 battery draining fast

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