Also make sure that adapter and cable compatible with handset.
I hv a strange experience recently. I bought a micro usb charging cable, when I use that cable with original Redmi 5a adapter 5V/1A phone charge very slowly (100 mA) but if I use Redmi 2 adapter 5V/1A then Redmi 5A charge fast(850 mA). No issue with JioFi adapter also.
So it may seems Redmi 5A adapter is faulty but if I use original Redmi 5a cable or original Redmi 2 cable then same Redmi 5A adapter charge Redmi 5a fast(900 mA). On the other hand Redmi 2 adapter with new cable which charge Redmi 5a fast but very slow charge JioFi device ( only 10% in 80 minutes).
On the other hand if I use JioFi adapter with Redmi phones then phone charges fast but at 99% phone starts behaving weirdly . Screen on and off continuously with charging connecting and disconnection sound but no such issue if I use original adapter .
So moral of the story : I think it's better to use original adapter, cable . I think it has something to do with mobile charging circuit