A battery management system comprising a main battery and a backup battery. A load is electrically connected to the main battery and the backup battery through one or more switches (e.g., FET switches). A voltage monitoring circuit is electrically connected to the main battery, the backup battery, and the load, wherein the voltage monitoring circuit monitors a voltage from the main battery and triggers a changeover to the backup battery based on a threshold and wherein a main battery interface path within the circuit is facilitated by a bypass diode for automatically switching the circuit to avoid power interruptions.