This picture is the current system I am fitting to my sailboat … I need to charge the 12V bank (which supplies all the boat loads) from my main 48V bank. In a perfect world I would fit an Orion XS 48/12 50A but it doesn’t exist.
Victron Orion 48/12 30A isolated charger
I guessed that was the answer, but have seen people abusing MPPTs for this job. Really looking for a 50A solution that is a bit more efficient. A direct competitor to the Mastervolt MacPlus 48/12 DC/DC.
… and a space heater 
I have one Orion-Tr Smart 48/12-30 on order so will see how it performs. Maybe double it up or wait a bit for a more efficient solution.
Redundancy is a bit of a double edged sword … on the one hand if one fails, you still have 50% capacity, but on the other hand, you have 2 devices so double the probability of a failure - and when one fails I’m compelled to replace it anyway. I tend to go for up-sizing and carrying spares, if spares are safely stored then they are unlikely to fail in storage so can be swapped out to get everything back to 100% capacity while the replacement is on order.
… very true based on the age of the spare parts that came with my boat.
