Sensar Boat Monitor w/Bilge Sentry [BMBS700]Boat Monitor with Bilge Sentry The Boat Monitor is the system's brain where data from the boat is continually collected and sent to the app. The system runs on an internal battery with 40 days of power and charges itself every time a boat's batteries are being charged. In other words, it is completely maintenance free and will monitor the boat for years without removing it to charge. Features: The boat monitor can monitor up to 2 batteries and bilge