Some devices may actually discharge when they are charged from port that don't supply enough power. See http://uros.com/public/blog/how-to-charge-your-mobile-device

The device is not useful. I don't understand why make such a fuss about it, because it doesn't work if you change shoes, get drunk or do anything that makes you walk diffrently than before. Seems that there is no cure for this, without breaking the usability of device.