Phones that will not charge, charge slowly, lose fast charging, stop at a percentage, or behave unusually while connected to power.
If charging stops when the cable moves, test another known-good cable first. If only one cable cuts out, the cable is likely faulty. If several cables disconnect when the plug moves inside the same phone, check the connector fit, debris or charging port.
A phone may stop fast charging when it gets hot because its thermal protection system reduces charging power to control battery and device temperature. Fast charging usually returns after the phone cools if heat was the cause.
A phone can charge slowly while it is being used because the screen, processor, mobile data, gaming, video, navigation or other active tasks consume part of the power coming from the charger. The charging speed can also drop when the phone becomes warm and automatically limits charging power.