iPhone 6 discharging WHILE PLUGGED IN

I always check when I'm charging to make sure the indicator turns green and the lightning bolt is displayed (though without my glasses I have to assume that little blob is a lightning bolt). Also, when I'm plugging into my truck, it forces me to unlock the phone before it will use the USB port (that was new with iOS 11 I think), so I pretty much HAVE to look at it.

I've had the lint problem before (bad enough that the plug wouldn't stay in) and this is not that. Ever since then I keep an eye on the lint collection in both the charging port and the headphone jack (which I've had the same problem with). You're right -- that will do it, but it I was literally watching the state of charge go down -- right next to the green battery icon and lightning bolt -- until it hit about 37%, then it rebounded and came back up to 100% in about 20 minutes.

I've come to expect bizarre battery behavior from this phone, but I've never seen it do THIS before. I have sat there and watched it run down before my very eyes, which doesn't seem normal either, but I can't detect anything that would explain it. Unless it's been co-opted into a bot net that's mining bitcoin or something, I can't come up with an explanation. Last night I rebooted it to halt the downward spiral, but tonight I didn't even do that. It just stopped when it hit 37% and started winding back up again.

Weird.

The article kind of supports what my SO and I were speculating -- it's not that the battery is actually changing charge states that quickly, but that the system THINKS it is, and is reporting it accordingly. Which makes some sense, since restarting the phone sometimes appears to fix the problem. But when I got up at 6:00 and unplugged at 100% after charging overnight, I was down to 81% by 6:11 when I sat down to check email. In between? I ran a 2-minute timer in the clock app. That was all. Another point of weirdness I hadn't seen before happened last night. I shut the phone down hoping to reset whatever was running amok, but when I tried to start it back up, the screen displayed the "red-sliver-of-battery-with-charger-cable" symbol on the screen and refused to turn on. But when I plugged it in and turned it on? It said it had an 80% charge.

Background refresh is turned off for any app I'm not currently using, and the worst offenders (Safari and Maps) stay shut down entirely unless I need them. I have no social media apps running (because I have no social media accounts) which are bad for running background activities. So I'm left to conclude that the OS is simply confused. Which doesn't change anything, since the phone will behave as if the charge is running down whether it actually is or not.

But at least after reading the article you linked, I know I'm not crazy. That's something, I suppose. Much as I hate the idea, it's starting to sound like a trek to the Genius Bar may be in order. This looks like it needs more diagnostics than are commonly available to the end user.