With every iteration of Android it seems that Google adds just a little more to the operating system which makes it that much more useful to users. Those looking to get a taste of things on the bleeding edge before Google rolls these functions out to devices have been able to do so since last year thanks to Google's introduction of the developer preview for the upcoming version of Android. This year, Google released the Android 6.0 Developer preview at Google IO 2015, which at the time was known as Android M, and since then there have been two other releases with the third having been recently made available just this month.
Each version of the preview has brought about some revelation of what users will be able to expect once Android 6.0 Marshmallow begins to hit devices later on this Fall, and alongside some of the features we already know about, the latest discovery shows that the third developer preview gives users a little more detail about their battery statistics. If you're someone who wants to have even the most minute details about your battery usage than this is likely what you've been waiting for, or at least partially. With the latest preview release you can now check your battery usage on a single per app basis in mAh hours.
To be clear, checking out battery usage per app is not new, but being able to see the usage in mAh hours is. This could be particularly useful to people who are curious to know how many mAh from their battery are being eaten up by specific apps each day. It's not likely something which every user is going to care about, but it makes perfect sense for the details to be available since mobile phone batteries are measured in mAh hours. These sorts of details will obviously vary depending on how much you use certain apps, but no matter how large your battery this gives you one more to break down your battery use data. Whether or not Google keeps this function in the final release of Android 6.0 is unknown, but there's no reason why they shouldn't.