The BMV-700 is a high precision battery monitor. The essential function of a battery monitor is to calculate ampere hours consumed and the state of charge of a battery. Ampere hours consumed are calculated by integrating the current flowing in or out of the battery.
To read more about the full BMV range & accessories, see this blog.
6.5 - 90 VDC, requires dongle for Bluetooth, includes shunt and comms cable