This review of a Fazua equipped bike says the unit must be at least partially removed to charge, and recommends removing it completely to charge. https://www.cyclingweekly.com/reviews/e-bikes/focus-paralane2From the Fazua manual:
Charging the Battery Pack
The Battery Pack (8) can be recharged at any time on its own, within a Drivepack (1), or within your eBike.
Also note the location of the handle bar mounted control in one of the article photos.