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The article below may be able to help you with this.
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You can use the iPad mini charger to charge the iPhone 5C, but not recommended the other way around.
The article below explains that the iPhone charger is meant to charge only iPhones and 1st generation iPad mini.
To charge your iPad battery, try one of these:
- Connect iPad to a power outlet using the included cable and USB power adapter (use the table below to determine which adapter is intended for your iPad.)
- Connect to a high-power USB 2.0 port using the included cable.
Note: Some USB 2.0 ports and accessories do not provide enough power to charge iPad. When this occurs the message "Not Charging" appears in the status bar next to the battery icon.
I hope this information helps ....