Qmobile Z10 has got occasional slow charging problem and I have figured out why this happens. If you connect any other charger than the stock charger provided with this phone, charging will slow down. In fact, whenever you connect some other charger, a pop up appears that says charging will be slower. This problem becomes permanent even if you connect the Z10's own charger. To fix this problem, shutdown your phone and restart it. (Do not restart it directly by pressing Restart button. Shut it down and start again). The battery will re-synchronize properly and slow charging problem will get resolved. This is 100% working fix.
Avoid charging this phone with car charger or power bank or some other phone charger or you will keep facing this issue.