Re: why mobile is charging very slow
We need more details:
What is the exact phone model that you're using?
How slow is "slow"? How many % per hour or per minute?
The most common power drainers are the screen and the mobile data antenna. If any of these two are active while charging your phone, charging would definitely be slower than when the phone is left idle.
The screen is active when you can see something on it (obviously) aside from Glance screen.
The mobile data antenna is active when you're downloading something, browsing, or if the signal quality is poor.
Other common causes of battery drain (even while charging) include: using the phone while charging (browsing, playing games, reading, taking photos, etc.), background downloading of updates, leaving the camera active - make sure none of these are active while charging your phone.