Head unit not charging iPad
In my car i have an after market HU with a usb port that my iPad 3/ iPhone 4s / iPods can connect to. However when my iPad is connected to it is unable to charge. The charging indicator in the iPad has the little lightning bolt going through it, indicating that it is indeed charging however the iPad looses about 7% of its battery every hour. Does anyone have any suggestions on how i can get my iPad to charge through my HU?