Your BaseCharge can power multiple devices at once so long as the total power required stays within the limit of your unit's max output wattage. For BaseCharge/+ 600 this is 600 watts, for BaseCharge/+ 1500 this is 1200 watts. Refer to your BaseCharge's smart dashboard for real-time feedback on how long you can run or recharge your multiple devices until BaseCharge is empty.
Note: for wireless charging, the BaseCharge can only recharge a single device at a time on the wireless deck.