The DigiTrak XT Monitor automatically tests the power of a battery when you insert it to make sure it will last the entire length of time you would like the patient to wear it. Upon battery insertion, it also tests the Monitor software and sealed memory to make sure they are operating correctly. If you forget to start the DigiTrak XT Monitor before sending the patient home, it will automatically turn itself on and start recording if it detects a heartbeat for longer than 30 minutes.