I need something that will report the battery level to the an arduino controller so that it an alarm will report when the battery level is below a certain point and it will be able to lock other functions that the battery would not be able to handle.
So you can use a voltage devider to monitor the battery level using one of the analog pins. You can use a pizo buzzer as an alarm if you want. For locking functions if the arduino is the controller you can have the software just not allow the code to run if voltage is too low. the other way is use the arduino to shut off a relay that powers the function you want to run.