iPhone X Battery draining overnight - Apple support not much help - thoughts are welcome

My iPhone X is still under monthly warranty. In fact, I had a battery replacement done once already, I think about a year and a half ago. Currently Settings > Battery > Battery health says it’s at 97%. And an Apple remote diagnostic doesn’t report any problems.

Last night was an example of the problem. When I went to sleep the battery was charged at 80%. When I got up it was down to 9% with low power warnings, and then died before I was able to plug it in.

I usually charge wireless, but in cases like this I will plug it in or it will take forever to charge up again.

In Settings > Battery nothing seems to be using a lot of power. Here are the first items on the list. Are these the last 24 hours?

Screen on 3 h 29 min, Screen off 4 h 8 m

If that’s since I went to bed it’s really strange that it would report screen on for that long a time.

  • Words 2 - 17%
  • MapMyRun - 9%
  • App Store - 9%
  • Home & Lock Screen - 7%
  • Facebook - 7%
  • Mail - 6%
  • Outlook - 5%
  • Messages - 5%
  • Reddit - 4%
  • Google Photos - 4%
  • Photos - 4%
  • Amazon Music - 4%
  • Safari - 3%
  • LINE - 2%
  • MyFitnessPal - 2%
  • BBC News - 2%
  • Camera - 2%

and so on.

It’s also sometimes hard to charge past 80% because the iPhone goes into some “intelligent charging” mode where it decides it should stop charging at that point.

Any ideas?


Just to answer this, you can turn this off in Settings / Battery / Battery Health. At the bottom, you can turn off Optimized Battery Charging.

I’ll check that out after the 15.0.1 upgrade is done. I’ve never been clear why they have that mode. I thought modern batteries couldn’t “overcharge.”


It’s better for long-term battery health to hold charge at 80% while the phone is plugged I for a long time and the charge to 100 when the phone calculates when you normally take the phone off charge. So, it watches for charge patterns to see if you tend to always plug in at 11 pm and take the phone off charge at roughly 6 am (this is my typical pattern), charge to 80% and hold it there until a couple of hours before you normally stop charging, and the continue the charge to full. That way you almost always wake up with a fully charged phone but it has been fully charged a minimal amount of time.

Also, this:

Weird. Well, it’s obviously bad at learning my pattern, which is to keep it on the wireless charger until I go to bed at about 10 pm, at which point I take it off the charger. If it was good at learning it would let me charge to 100% before I went to sleep.

It might not make a practical difference as to long-term battery health because I keep my iPhone under AppleCare+ warranty.

I got rid of Outlook and Spark, both of which seemed to be making use of batter overnight.

The battery still drained from 82% to 29% overnight.

Looking at the hour-by-hour usage it seems that most of the remaining battery drain is due to Siri. Does it really use that much battery just sitting there listening?