Understand iOS Low Battery logs Good morning everyone. I'm kinda new to this site but I see there are many expert opinions, so I would submit to you my question, hoping it will be helpful for someone else. Before proceeding, I beg your pardon if I make mistakes in my English (I'm italian). Anyway I will try to be as clear as possible. I'm trying to figure out what is the means of the Low Battery logs on iOS.

In particular, I wonder if I can tell if there is a problem on the device, (a process that drains the battery, say,) or if there's actually a problem with the battery itself. For example, let's take as an example this snippet of log, taken from an iPhone 5 from my cousin:

Hardware Model: N42AP
Awake Time: 02:41:19 (9679)
Standby Time: 11:26:34 (41194)
Partial Charge: 0
Capacity: 0
Voltage: 3647 mV


I know that the Awake Time and Standy Time refer to the time that the device has been operative and in standby from the last recharge.
But what is the meaning of Partial charge, Capacity and Voltage?
Your question is a great excuse to update and expand my previous answer on interpreting these diagnostic logs.

The partial charge field is a simple binary field. A zero means you didn't plug in your phone and these logs document how much usage you got out of a full charge. A one value means that you did plug your phone in after the last full charge and that the readings document more than one full charge - perhaps the phone was working for weeks and kept getting plugged in before finally running out of power. 

The log only gets written when the device literally shuts itself off after all of the power warnings.

Voltage documents the voltage of the battery when the device shuts itself off. There usually is still some charge left to power the display briefly and show you that you need to plug it in. Eventually the voltage will decay so low that nothing will run until plugged in again. 

Capacity Documents what the power management chip thinks should be left in the battery at the point the log is written. I've never seen a device where this isn't zero.

Here's one of the logs I've collected on my iPhone six:

Hardware Model: N61AP
Awake Time: 07:48:22 (28101)
Standby Time: 11:30:25 (41425)
Partial Charge: 0
Capacity: 0
Voltage: 3409 mV