Downloading BatteryNotifier 1.3 for Mac from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this free software for Mac is Kalvin Loc. The application lies within System Tools, more precisely Battery Utilities. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe.
From the developer:
BatteryNotifier is an OS X tool that warns you if your iOS devices need a charge. iOS devices broadcast service announcements continuously when they are awake. Once they go to sleep, they broadcast exponentially such as after 1 second, 3 seconds, 9 seconds, 27 seconds, and so on, up to a maximum interval of one hour. An iOS device and your Mac must be on the same network or connected via USB for BatteryNotifier to work.
You may want to check out more software for Mac, such as DssW Sleep Monitor, iPodBatteryIndicator or Battery Checker, which might be related to BatteryNotifier.