XS max standby drain "too high"

Alexander Lake wrote:

Update: Got a replacement phone (a swap by the insurance company) and the new one is WAY better. Took about 4 hours to lose 1%. Oddly, the battery health indicator was only 90% (compared to 91%) so that seems to be only a partial indicator of battery condtion. Something to look out for.

That’s true. Capacity loss is only one battery failure mode. A partial short in the battery can also cause energy drain, and high internal resistance can cause the phone to shut down unexpectedly, or cause the state of charge to jump around. A useful test of what’s called “self discharge” - charge the phone to 100%, unplug it, then shut the phone off completely (hold the Side button and Volume Up until "Slide to power off" appears, and do so). Put the phone in a safe place for at least 8 hours. If the battery is good it should still be at 100% (or very close) when you turn it back on. Some other failure modes can be detected by the battery monitor, and will result in a message that the battery is degraded in Settings/Battery/Battery Health, but not all failure modes. Apple techs do have a more comprehensive diagnostic that can find additional battery issues that aren’t displayed on the phone.

Yes, they can be run remotely. They give you a link to download a profile that can report additional diagnostic data; once the test finishes the profile is deleted.