Hi,
generally speaking:
Almost every device (IC, transitor, resistor...motor...) comes with a datasheet.
the one who is building a circuit needs to read the datasheets (professionals do this, hobbyists should do the same) and needs to keep on the given specifications.
Just connecting battery voltage to two wires of a BLDC motor will cause overload, killing parts, maybe fire...
The above question is not stupid. Those and similar questions need to be answered when professionals design circuits, too.
What do one need for a detailied answer/calculation to this question:
* power supply voltage
* driving circuit including specification (datasheet)
* motor type including specification (datasheet)
* any other involved parts and their datasheets
* maybe a complete schematic and wiring diagram.
... and ohm´s law...
math skills: + - * /
Klaus