The whole point of a non-removable battery (from my point of view) is to ensure that the case must go into the cabin and that it's a big no-no for it to be checked into the hold, for example at the gate. It creates a problem for the airline but an ideal scenario for the passenger.
Pretty sure if it's not-removable the airline won't accept it as carry-on or checked baggage, at least in the US. Maybe someone can validate that.