Hi and welcome to the forum.
It looks like you may not have read similar articles on charging issues 
Here are some links and ideas.
Meanwhile.
- How old is the phone
- You don’t provide any details on the chargers and cables you have tried.
- Did you check the battery dial
*#*#66#*#* Service tests > Test Single > Battery status check
- It still could be the cable
A fast charger may have been wired diagonally symmetrical so it will not matter which way the cable is inserted, but some haven’t - If the charger and the cable are not both wired symmetrically then it will only work in one of four connections
- If there is a fault on the USB module on the phone, in that it also isn’t working in both directions then you only have a chance of 1 in eight if all there are not 'diagonally syymetricaly wired@
So can see you will requires some patience to work it out.
- A QC3 compliant charger that is confirmed to work both ways and USB C charging cable that is properly wired or not damaged. And then even if the phone USB can only charge in one direction it won’t matter.
You may want to clean the USB port on the phone where thing sometimes seem OK and other times not.
You don’t say which type of USB ports you are using on the computer USB A of USB C for example. If the USB A then check the inside to see if it is black or blue.
The black supply 5V with a maximum of 0.5A whilst the blue do 5V at 0.9V neither of which are ‘powerful’
There are no ‘normal’ chargers except the ones you are used to. There are a few protocols for charging for different makes