If you truly possess a:
1. BMW Wallbox -- it should be hardwired in a more or less permanent manner; and I assume it was. Clearly instruct your electrician to hardwire your BMW Wallbox to a dedicated 50 amp circuit. You can charge at 80% of your amperage, meaning that with a 50 amp circuit, you'll charge at 40 amps (which is 80% of 50). This will provide ample juice to charge, for example, from 20% to 80% in approximately 6-7 hours.
To charge your vehicle, you will need a portable EVSE, which is a charger from any manufacturer. This charger should be plugged into a NEMA 14-50 outlet, similar to the one used for your dryer. In contrast to the fixed BMW Wallbox, this device offers the convenience of being unplugged and taken along for longer road trips, although it's not recommended to frequently plug and unplug a portable EVSE. Once more, it's essential to inform your electrician that you require a dedicated 50 amp circuit to achieve 40 amps of charging.
If you have an older home with a 100 amp panel and wish to avoid overloading it, you might consider installing a 40 amp circuit, which would provide 32 amps of charging capacity. Charging from 20% to 80% can still be accomplished in 8-9 hours, which is useful if you typically need or want to charge 60% of your battery at once.
If you’re unsure about the amperage available for your "charger," whether it’s the BMW Wallbox or a portable unit, and the electrician didn’t label it in your electrical subpanel, you can simply turn off each individual circuit breaker to find out. Every breaker is labeled with a number, usually 15, 20, 40, or 50, indicating the amperage for that circuit. Flipping off the breaker that powers your EVSE/charger will reveal the amperage your charger is operating at, as indicated by the number on that breaker. I would wager that your electrician connected it to one of the lower amperage breakers, either the 15 or 20-amp ones.
By the way, it seems you don't have an i7. With at least i7s, you receive a complimentary BMW Wallbox and I think there’s a $1,500 (or possibly $2,000?) installation credit available through Qmerit! The i7 is a high-end option, so it may or may not be available for your specific vehicle.
Finally, search for "Youtube, setting up home EV charging," or a similar phrase, and view several videos that cover the details of standard EV home charging installations. With that fundamental knowledge, you'll find it easier to handle this situation and communicate with your electrician. Hey, just a year ago, I was completely in the dark about this myself! We harvest the results of our actions, you see?
