Can I Charge Ipad With Macbook Charger. The charging time is longer than the original usb-c charger. When I connect the Mac to the iPad charger and keep working on the computer its keep the battery percentage the same add 1 every 15-20min.

I feel if the charger is MFi or of a quality brand then you should be ok to be on the safe side I wouldnt leave it charging. I read that I can use my MacBook Pro 13 charger for the iPad but ogher voices say you shouldnt. A smaller source than needed is not safe.
Just connect your device to the power adapter with the USB to Lightning cable 30-pin to USB cable or Apple.
But what if you already have a higher-powered USB-C charger from your MacBook Pro or MacBook Air. Not a good idea. An iPad charger also provide similar range of voltage that is suitable for charging iPhones. In the system info you will find the battery status is not charging.

