Every DC-DC alternator charger in the catalogue: Victron Energy Orion-Tr Smart in 12V-12V, 12V-24V, 24V-12V and 24V-24V combinations from 10A to 30A, isolated and non-isolated, 100A Buck-Boost units for smart alternators, and Redarc models with an integrated BMS.
A DC-DC converter is mandatory when the service battery is lithium: the alternator delivers a fixed voltage that never completes the charge of a LiFePO4 pack and, if the BMS opens the circuit without warning, it can damage the alternator regulator. The DC-DC acts as an interface and caps the current drawn.
When choosing, look at input and output voltages, current rating, galvanic isolation and compatibility with Euro 6 smart alternators.
