Victron Orion-Tr 12/24-15A Isolated DC-DC Converter - ORI122441110 15AH followed by approximately two hours

followed by approximately two hours rest in discharged condition

If both your start and house batteries share a common negative return (ie chassis ground) then you do not need the isolated version

Victron Centaur Charger:

The Inverter RS Smart Solar is a combination of a powerful 48VDC

NOTE: "BlueSolar" units do NOT have Bluetooth built in which means you will need to purchase a separate VE

Victron Orion-Tr 12/24-15A Isolated DC-DC Converter - ORI122441110 15AH followed by approximately two hoursVictron Orion Tr DC DC Converters Isolated: A DC DC converter converts one DC voltage to another. The operating voltage of different electronic devices can vary over a wide range, making it necessary to provide a voltage for each device. The Orion IP43 DC DC Converter is short circuit proof and can be paralleled to increase output current. An unlimited number of units can be connected in parallel.