I have bought an used iphone 8 plus yesterday. It s working all right after some testing, before I I got to sleep, I charged it 100%, when I woke up today I found it 80%. I find it completely not normal, what might I check to see what s the problem so I can contact the seller?

  • What does Settings / Battery / Battery Health say?
    – lhf
    Sep 18, 2020 at 12:55
  • it says 80. How bad is that?
    – Papa
    Sep 18, 2020 at 13:02
  • 1
    80% charge just means one cycle didn’t finish. 80% capacity is different - that’s where you start to notice a slightly shorter run time but still quite good for 3 year old device typically. Hopefully my answer helps you get some more details on what your health is. Used phones typically have used batteries so check what a service would cost so you know how to approach the seller if you feel mislead.
    – bmike
    Sep 18, 2020 at 13:10
  • I have in battery usage by app 26% for home lock screen, 22% camera as main ones, ant tips?
    – Papa
    Sep 18, 2020 at 13:27

1 Answer 1


I love the new graphs that show you what happens in the battery for this over time.

iPad Pro battery curve showing overnight charge in the settings app

Here’s what an iPad Pro that’s cranky after updating to iOS 14 and not recognizing the Magic Keyboard looks like sitting on a desk overnight, power to the keyboard hinge port and clearly not taking a charge. The gap before the brief charge was caused by a forced reset requested by Apple Support to triage and isolate what’s going on.

Here’s an iPhone getting much better charge results than the human did last night.

iPhone battery curve showing overnight charge in the settings app

You can track things each day and get an excellent picture of what your device is doing before needing support to run a battery diagnostic in my experience.

Once you have some details and have read about the terms, maybe get Apple to see if you want a battery service?

I generally wait till it’s 45% to pay as I’m ok managing it and want to get the most life out of a safe but aging battery. You’ll want to be sure it’s not software or a busy app, though before any repair since a stuck app can drain a perfect battery rapidly.

  • I see. Well, I just bought it yesterday. It is was charged super super fast. Now, I never used an iphone before, when I double clicked on the home button, I found I had 12 apps remained active during the night. That s what got the 100 to 80 in 12 hours. I got Iphone 8 plus with 390$ with battery health 80% and it seems not scratched and everything, is that a good deal?
    – Papa
    Sep 18, 2020 at 15:38
  • You can’t tell if an app is active from the multitasking tray. Every app you ever launch shows there. Power down the phone and restart, the saved image of the app when it went to sleep is preserved even when the process is killed. I’d see what Apple offers for trade in on that device to start a value chain. I have no idea what things go for and prices should be depressed now as people unload devices in anticipation of new release. They really drop when people can buy the new hotness (in past years).
    – bmike
    Sep 18, 2020 at 15:50
  • 1
    I played a video on youtube for 1 hour and it consumed -10%, convenient?
    – Papa
    Sep 18, 2020 at 16:44

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