You get this functionality (varied battery level warnings) built into iStat Menus (often available in a bundle from MacUpdate so you may already own it). This is a great free offer for those who don't have iStat Menus but it's one less utility to run if you do own iStat Menus. Highly recommend 20% battery level warnings as 10% doesn't leave you much time.
Have been using iBetterCharge for a couple weeks. It has been a great help. I'm the type to let my phone battery get down to 5% or less. Often being distracted, I wait too long and the phone dies. It is inconvenient to plug in the phone for a few minutes before it will turn back on. iBetterCharge solves my complacency. Even better, they (Softorino) listen to suggestions. They wants to provide a great product and take suggestions seriously.
Very often the iPhone warning of 20% or 10% is enough to charge a battery and feel yourself comfortable. But sometimes the situations happen to be unexpected, when your phone is not near at hand and you totally forget about it. iBetterCharge is a great solution for such cases. Nice app, recommend to try.
Used to be great but it stopped working sometime early this year (2016). Developer asked me to reinstall then, when it still didn't work, told me to wait for a new version. That was in Feb or March I think. 3 stars for support responsiveness and for how well it used to work. Hope it gets fixed. Also, noticed that the self-update now results in an error so it seems the developer has abandoned the update url...
I've been TRYING to like this but it is constantly losing the connection with the phone unless it is connected by usb. It works only about 20% of the time and then only to show a near full charge. I wish you could fix that!!!
This is a great application, but it seems to have stopped working for me now after I installed iTunes (11.2.1).
I have done all the suggested troubleshooting (re-attach via USB, unlock device and trust computer, enable Wi-Fi sync), but when I re-attach my devices, they appear in iBetterCharge, but after 30 minutes or so they disappear. iBetterCharge just seems to constantly search for them even though the device is sitting next to my iMac.