Charging time underground long

Have brought for my Z2 me this adapter cable. After 1.5 hours, a mere 13 to 31%. With Micro-USB directly in 15-20 minutes from 31 to 41%. Can you perhaps take if you have a lot of time, but to "just" charge such as overnight, but it definitely is not good. Now the conflict; Fast upload via USB port, but every time what you have to open the plastic closure, which certainly leads to the time that it wears off, as it is in my opinion a predetermined breaking point or calms externally but extremely slow to load. I think I'll send the cable back and only use the dock when it then invites hopefully faster.