iOS has had widgets since iOS 8. There are some stock widgets that accompany the stock apps and third-party apps that you install come with widgets of their own. iOS has a battery widget at as well. It shows you which devices are connected to your device and their respective battery percentage. You can add the batteries widget the same way you add other widgets on iOS. The widget has been a part of iOS for a long time but for some users, it isn’t even in the list of widgets that can be enabled. This isn’t a bug. It’s more of a default omission by Apple. The missing batteries widget will appear when you pair the right Bluetooth device, and it will stick around even after you remove the device.
Missing Batteries Widget
In order to get the battery widget to show up, you need to pair and connect a device, over Bluetooth, that can report its battery percentage. An obvious choice is Apple’s Airpods. If you pair and connect them to your iPhone, swipe right to the widgets’ panel, and tap edit, you will see Batteries appear in the list.
Other Bluetooth devices can work too but there’s no conclusive list of devices that, when connected, will make the battery widget appear. Some devices will force it to show up, others won’t.
If you pair and connect a Bluetooth device, an icon for the device appears in the status bar. If the icon is accompanied by a battery icon, it very likely means the device will enable the battery widget. If you’re about to buy a Bluetooth device, it’s a good idea to check in advance (Google it) to see if you’ll be able to check the device’s battery information on your phone or not. If you want to force the missing batteries widget to appear, you can probably just borrow a Bluetooth device and pair it to get it to show up.
Compatible Bluetooth Devices
Bluetooth devices that are advertised specifically for the iPhone or iPad are the ones most likely to force show the batteries widget. Other devices that aren’t advertised as such will connect with an Apple device but it’s far less likely that they will force the widget to show.
Devices that cannot force the widget to show will not appear in the widget even after it has been enabled. This is because a device needs to support the widget’s API. Additionally, not all Bluetooth devices make their battery information available which, crazy as it is, happens.