Note for dual battery installation with a DC/DC charger when using a lithium starter. Please ensure there is a relay on the supply side to the DC/DC (main positive cable from start battery to the dc/dc) that is only closed/on when the vehicle is running.
We use the NARVA 200A heavy duty as a preference but any relay above the rated input of your DC/DC will work fine connected to an ignition source. These are a capable and robust relay with the bonus of threaded posts for an even more sturdy install.
With the slightly higher resting voltage of lithium starter batteries, the DC/DC needs to be disconnected from supply when the engine is not running to ensure the lithium starter doesn't drain into the aux system.