The functionality of the Cyrix-Li-ct is analogous to the Cyrix-ct.
The Cyrix-Li-ct will parallel connect a lead acid starter battery and a LiFePO4 battery:

if the charge disconnect output of the VE.Bus BMS is high, and
if it senses 13,4 V (resp. 26,8 V) or more on one of its power terminals

The Cyrix will disengage immediately:

when its control output becomes free floating, signalling cell over voltage or cell over temperature, and/or
when battery voltage drops below 13,2 V

Start assist function: a short positive pulse will close the relay during 30 seconds.
A built-in transient voltage suppressor will limit the voltage spike that may occur when the Cyrix suddenly disengages due to cell overvoltage or over temperature.