I had bought xio mi powerbank of 10000 mah which I charged it overnight and used for my mobile phone to charge it could charge only one and half the time. I did it twice but I experienced the same thing.
So I returned this product as it was surely not worth the money though I bought sony 5000 amp power bank which I use it for one and half time.it is very light weight and it is worth the money. I charge the power bank sometimes for 6 hours and use it, yet it charges properly and I am very happy with this product.
Over all mobile accessories are good to buy as those are useful but need some study to be done before buying anything.