How To Fix Samsung Galaxy S8 Slow Charging Issue?

You could try to change charger or change battery. Other than that there are a couple of apps that promise to recalibrate your battery and speed up charging.

Samsung Galaxy S8 is a phone that has history. It was one of those releases that people thought were the next real breakthrough. It is a great product to buy so if you find one on the shelf, it's time to get one for yourself. Here are a few fun specifications of the phone to help explain to you how it is a great phone.
Display:
The display screen is 6.2 inches and has a super AMOLED capacitive touchscreen with 16M colors. This means that the color potential of the mobile phone will be off the charts and the screen will also be super strong due to a highly strong glass. The phone has an aluminum frame with a Gorilla Glass 5 that is again, pretty strong. It is water and dust resistant and the honey can stay in water for up to 30 minutes before losing functionality.
Core:
The phone has an amazing and simple core with Exynos 8895 that has 8 octa-cores. Four of the Octa- cores are 2.3 GHz Mongoose M@ and the other four are 1.7 GHz Cortex- A53. If none of this means anything to you, then it means the product can run on jet fuel ad not crash for a millisecond.
Camera:
The phone has a strong 12MP phone with dual pixel DAF, LED FLash, auto- HDR, panorama view, stereo sound recording, gyro- EIS, PIS and includes dual video call. The video options are 2160p@3-fps and lower. The video and pictorial results of the camera are truly amazing.
Extra Features:
The phone has a WLAN, dual-band, W- Fi Direct hotspot and a GPS with a USB connector. The phone also has an iris scanner, active noise cancellation with dedicated mic. A fingerprint mounted in the back and compass, barometer, heart rate monitor, Sp)2, gyro, proximity, accelerometer, and a Samsung Dex hat will make your phone compatible with desktop monitors.
Colors:
The phone comes in a long range of colors including, midnight black, maple gold, rose pink, coral blue, arctic silver, orchid gray and a strong 3500 mAh battery.
There are many reasons to buy this phone, we listed the best few in this piece. Best of luck with phone shopping this Christmas and may you get amazing deals in the market!

Are you using the original charger that came with the phone? If yes, there might be an issue with the USB cable you're using. Try using another USB cable and make sure it supports fast charging.

Just change battery