Bluetooth Battery Level Indicators May Soon Be Coming To Android (androidandme.com)

The folks over at XDA Developers are reporting that Android may be getting a new feature that could help users identify how much battery life is remaining in their Bluetooth wireless headphones. The feature for "[retrieving] battery level information of [a] remote device" was discovered in the Android Open Source Project (AOSP). Android and Me reports: This hasn't made it to final release just yet, but when it does, it will make it easy for users to quickly ascertain how much battery life is remaining in the Bluetooth headphones that are connected to their device. It doesn't just mean support for Bluetooth headphones, either, as Bluetooth speakers and other accessories that run on battery power will be supported, too. Unfortunately there's no telling on when this feature will see the light of day for the public. There's no set timeframe between a feature that's part of the AOSP and rolling out in a final, public release of the mobile operating system. Some manufacturers have already built support for this feature into their phones, including OnePlus, Samsung, and LG. So while it might not be a completely brand new feature on Android, it would still be good for the Android platform as a whole to support the feature in the stock build.

Comments

It's standard - but support is not.

[Ungrounded Lightning]

There is a "battery service" defined in the standard.
(At least for BLE, aka Bluetooth Smart, but I assume also for Bluetooth Proper, as well.)

While nobody is forced to implement it, or implement it correctly, It's there - and built into the software development kits for the Systems On a Chip. If your device uses a common coin cell and the default power handling, you can just turn it on in the build and have it in your application - and any Bluetooth (or BLE) central can use it.

The BLE one gives you its best guess of the percentage of battery life remaining as a number from 0 10 100.

Now some batteries (for instance, Lithium Thionyl Chloride) can't be measured accurately (or at all before the last 15% of their lifetime). So battery services for them tend to hand you bogus numbers, if there isn't a "gas guage" chip counting switching regulator cycles, and thus electrons, to make a halfway decent guess. But that approach gets less accurate as end-of-life approaches, when you really want it to get better as you approach the wall.