I have a problem with an installation that has a Cyrix Li Ct 120A, but Victron BMS. So the pin 85 cannot stay unconnected and free-floating. It cannot be connected directly to positive because the closure of the start-assist push-button will create a short cut. Is it acceptable to connect it to positive with a resistor that will limit the current when the start-assist is closed ?
The VE Bus BMS has a current output of 10mA, so you could put a resistor in the 12V wire to terminal 85 with a 1000 Ohm resistor to keep the start assistance current to ground low.
What may also work is to use a normally closed switch in the 12V wire to terminal 85 as the start assistance button and pressing this twice will stop the +12V signal, so closing the main relay.