“Charged?” is a small app that allows you to check the charge level of your iOS and macOS devices via iCloud.

“Charged?” is free on both iOS and macOS.
The iOS version has a small banner at the bottom of your screen which you can remove via the in-app purchase, which also unlocks the widget.

Your devices sync their battery statusses via iCloud and uses bluetooth if they are nearby.
Using iCloud, Mac’s update nearly instantly as long as they are connected to a power source or awake when on battery power.
iOS devices will experience a slight to long delay due to the nature of how iOS background execution works.

You can easily hide devices you don’t care about or unhide them at a later date.

If you have problems with remote syncing please make sure you are signed in to your iCloud account and have iCloud drive enabled on the device in question.