Looks like the folks at Sure Power did there homework and put a lot of features into their new separator the 3104
It has a 300 amp latching solenoid. No power draw when in the closed or open state. They have made this ultra configurable, it looks like some models you can control the connect and disconnect voltage levels. It can be configured as as unidirectional, bidirectional, low voltage disconnect, and isolator/interconnect mode, manual mode. The real big draw back is the price of $300.00
Unidirectional Battery Separator:
This mode is used to charge two batteries from one power source. In this mode, the unit monitors the "main" battery. When the main battery voltage is above the connect threshold, the solenoid connects the two batteries together. When the main battery voltage drops below the disconnect threshold, the solenoid is opened. In this mode, the connect threshold is usually set to a voltage that is only reached when the charging system is operational. This will cause the solenoid to only close when the charging system is operational, charging both batteries. The RCM pin must be grounded in a battery separator application.
Bi-directional Battery Separator:
This mode is used to charge two batteries from two sources. In this mode, both batteries are monitored. If either battery is above the connect threshold the unit will close the solenoid. If the batteries are below the disconnect threshold the unit will open the solenoid. The voltage settings for the bi-directional battery separator remain the same as the unidirectional battery separator. The RCM pin must be grounded in a battery separator application.
Low Voltage Disconnect (LVD): In this mode, the unit monitors the battery voltage. When the battery voltage drops below the disconnect voltage, the unit opens the solenoid, removing power from the load. The solenoid closes, powering the load.
Isolator / Interconnect Mode:
This mode is used to charge two batteries from one power source. This mode provides the advantages of both the isolator charging system and the battery interconnect.
For the full spec sheet see edit: removed PDF as it was marked proprietary.
find it a one of these two locations