The brake mechanism is hydraulic or mechanical and will not be released when the battery is discharged.
Most cars you can buy on the market today have electric parking brakes. Parking brakes are becoming rarer. How do electric parking brakes work? They make it easier to move uphill and downhill because they block the wheels until they have enough torque to start the vehicle.
What if you pull the electric parking brake switch while driving? Will the same thing happen with a handbrake? No, it will not, because the control unit in the car recognizes this situation as braking the car and there is no wheel lock. The electric brake then applies force at intervals, ie the ABS is activated. Basically, concentrate and don’t pull the electric parking brake switch while driving.
The brake mechanism is hydraulic or mechanical and will not be released when the battery is discharged. That is, no electricity is required to maintain a firm brake grip.