I searched online and found that the Emmo Titan has a 60 Volt 20Ah battery pack and 500 Watt motor. 11km (7 Miles) is a very low range for a battery pack and motor of these sizes to have unless the bike is being used in an area with steep hills.
Dragging brakes can cause loss of range so it would be a good idea to check and see if the wheels spin by hand without resistance.
A 10 Volt drop for a 60 Volt battery pack that is under a 10 Amp (600 Watt) load is high. It is possible that the controller has a 20 or 30 Amp current limit though in which case a 10 Volt drop would be more normal.
If the problem were not with the battery pack then the lost energy would have to go somewhere and turn into heat. So unless one of the bike's electrical parts is getting extremely hot while the bike is being driven then the problem would be with the battery pack.
We recommend to remove the batteries and have them load tested at a battery store. This will determine if there is a problem with one of them.
If the batteries all test good then please let us know and we can take it from there.