While powered off the All Road's Blackbox will consume ~30mAh of energy. This is far lower than the average draw of most modern vehicles and should not pose a problem unless your battery is old and/or in need of replacement.

Periodically the Blackbox will turn its Bluetooth module on for a short time to see if the Handset is attempting to connect and thus prompt it to start up and return to its usual draw of ~0.9A to ~1.2A depending on if the unit is transmitting or not.

In a real-world scenario, if you're going to leave your vehicle sitting for two or more months at a time it's best to disconnect the All Road until you're ready to use it again. If you're going to leave your vehicle sitting for less time than that on average, it would be wise to ensure that the Handset is either unplugged or powered off between uses to prevent it from Bluetooth syncing to the Blackbox and returning it to full draw.