Victron Battery Isolating Relay

Cyrix Voltage controlled relays for lead acid and lithium batteries

Cyrix tension controlled relay comes in two versions.
Cyrix relee suitable for charging between lead-based batteries and Cyrix LIT suitable for charging to a lead-based battery and on to Lithium batteries.

The Cyrix relay works so that when the voltage on the star battery reaches 13.2 volts, Cyrix switches on and sends power on to the next battery bank. When charging stops and the voltage drops to 12.8 volts, the connection is broken.
Victron Cyrix LIT for lithium batteries connects and disconnects at slightly different voltages allowing it to be used between lead-based and lithium batteries.

Cyrix relays can replace diode separators that have a significant voltage loss.
Cyrix relays are well suited for use in connection with outboard motors.

Alternatives to Cyrix relays are Victron Argofet electronic battery separators, which Makspower recommends in most cases.
The Victron DC DC charger is also an option, especially for motorhomes and boats with outboard motors.