The iPower requires a QC 2.0 or higher charger with an output current of minimal 2A at 5V (10W). The default iPhone Adapter has a maximum output of 5W and is therefore not compatible with the iPower. Use the iPad Adapter or another third-party charger that has a 2A charging port.
Our QC 3.0 USB Wall Charger is fully compatible with the iPower. With its optimized output you will benefit from the full capacity of the iPower.