Charged? allows you to check the charge level of your iOS and macOS devices via bluetooth and iCloud.
Your devices sync their battery status locally via bluetooth and if you have an iCloud account they’ll sync via an internet connection as well. 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.
Should you encounter any problems with local syncing please make sure you have bluetooth enabled. 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.