We are using Cyrix-ct 12/24-230 in VW Passat B8 to isolate primary (starter) vehicle battery and our secondary battery that is used for powering additional devices. Main motivation is to ensure we are always able to start the engine.
Issue is that the primary battery is most of the time fully charged and hence the smart alternator is providing low voltage + there is voltage loss on the harness. If the engine is running, voltage on the secondary battery is 12.88 V. Temporary this voltage drops bellow 12.8 V that causes relay disconnection and the same time it is not enough to connect the relay again.
Is there a way how to reduce the connect/disconnect thresholds by 0.3 V?
DC/DC is not a preferred way as we usually want more than 100 A.