Voltage sensitive switch (charge divider on two batteries) and emergency battery parallel

This switch senses the charge level of two batteries (or battery banks) and provides excellent charge management for the second bank.
The switch allows two normally isolated banks to be connected the moment it senses a charging source (engine alternator or battery charger).
The moment a charging source is active the switch first lets the battery of the main bank (engine battery) charge, when it is at a voltage of 13.2 V the switch opens the circuit and allows the charging of the second battery (services battery).
The switch also acts as an emergency parallel. The parallel can be activated manually via the knob or via (on)/off switch on the dashboard.
Flush or external mounting.