There are lots of users reporting an issue for iPhone won’t charge or showing black iPhone screen even plug-in power adapter/ Lightning cable only showing. Before that follow the strict rules and some mind some point on some situation declared in this article. Most users are facing problem on when they charging iPhone through Laptop or Desktop via USB lightning cable or iPhone won’t charge in the car.
External, Portable battery charger for iPhone.
Follow the guide when iPhone won’t charge: Battery doesn’t charge
For charge iPhone, if you know you need 8 pin connector for iPhone 5/ 5S, iPhone 6, iPhone 6 Plus and iPhone 6S/ 6S Plus/ iPhone 7/ 7 Plus.
30 Pin connector: iPhone 4S or Earlier iPhone generation.
if you are Charging through any converter for then that’s not correct way to charge your device in Apple’s terms and conditions. You can purchase in one cup coffee price dollars from here.
in Some case your power adapter or wire might be short, So power leakage can damage battery (Short circuit) or iPhone. – Then try with another cable.
if your iPhone automatically turn off due to the very low battery (less than 1 percent). Then whenever you charge or turn on from plugged power cable. Your screen showing below screen for 10 minutes. Then iPhone will automatically start up. – For iPad turn on time is 20 minutes. 
Note: You can’t turn your iPhone like android or other smart devices. iPhone/ iPad takes some required battery before you try start with sleep/ Wake button. After connect it will automatically start.
Make sure your power outlets correct and working with other electronic device (Laptop/ PC/ Other smartphone).
iPhone won’t charge: Battery icon doesn’t showing charging mode
just restart your device, in charging conditions or Force restart iPhone. Get brief about way of restart iPhone.
After connect USB lightning connector, Showing message like
“This cable or accessory is not certified,
may not work reliably with this iPhone,
This accessory May not be supported by this iPhone.”
if you have electronic items cleaning kit, Available on Amazon or iKlear will clean debris from USB slot or 8 pin connector slot.
Related Article – Enable Battery percentage on iPhone
Still you faced problem on iPad or iPhone won’t charge then contacts apple support center in your country.