Options for a 48V input to 12v output battery charger?

Running a similar setup in my Transit — 48V lithium bank (Fogstar Drift cells) feeding into 12V loads for lighting and the compressor fridge.

Been using a Victron Orion-Tr 48/12-30A for about 18 months now and it's been rock solid. The isolated version is worth the extra if you're mixing battery banks, saves a lot of head-scratching with ground loops. Configures easily through VictronConnect and you can set it to only convert when the 48V bank is above a certain voltage, which protects your cells nicely.

A few things worth considering when choosing:

• Continuous vs peak current — some cheaper units (looking at you, various Amazon specials) are rated at peak, not continuous
• Efficiency — at these voltages a few percent difference adds up over a week of off-grid living
• Thermal management — the Victron derates gracefully in heat, cheaper units just die

The Renogy DC-DC converters are a budget alternative and I've seen them recommended on the boat forums, though I haven't personally tried one at 48V input.

Anyone running the Sterling Power B2B units in a 48V scenario? Curious whether they're overkill for a static van setup or whether the smart charging profiles make a meaningful difference versus a straight DC-DC.

Also wondering if anyone's daisy-chained two lower-amperage units for redundancy rather than running one big one — seems logical but not sure if there are any gotchas.

Hey @TransitCamper, the Orion-Tr is a solid bit of kit — good choice there. One thing worth checking if you haven't already is whether you've got the isolated or non-isolated version, as it makes a difference depending on how your chassis earth is configured. Also, 30A is decent headroom for a fridge and lighting, but if you're planning to add anything else down the line you might want to keep an eye on thermals in a confined Transit install — they can run warm in a tight space without decent airflow. Worth mounting it to a metal surface if you can. What's powering the 48V bank — solar, alternator, or both? That might affect how consistently the 12V side stays topped up. Looking forward to hearing how you get on with it long term!

Running a boat myself so a similar situation — 48V house bank feeding 12V kit like bilge pumps and nav lights.

One thing I'd be curious about for your setup @TransitCamper: are you running the Orion-Tr in isolated or non-isolated mode? On my boat isolation matters for galvanic corrosion reasons, but in a Transit I'm less sure whether it makes a practical difference.

Also worth asking — at 30A continuous, are you finding that enough headroom for the compressor fridge startup surge? I've seen compressor fridges pull some spiky current at startup and wondered if a 48/12-50A would've been a safer spec for a vehicle setup. Has it tripped or throttled back on you at all?

Worth noting the Orion-Tr Smart variant gives you Bluetooth monitoring and proper load-output mode so it only charges when the 48V bank is above a set threshold — stops you accidentally flattening your Fogstar cells trying to top up a 12V starter battery at 3am.

Also, if your 30A is proving tight (compressor fridges are grumpy at startup), the 48/12-9A and 48/12-16A units can be paralleled if you ever need to scale up without replacing the whole lot — Victron actually supports this officially, which is rather civilised of them.

One pedantic point: double-check your cable sizing on the 48V input side; people consistently underspec it because the currents look small, then wonder why the converter runs warm. Ohm's Law doesn't take days off.

@EwanCole58 snap — my 48V house bank runs through an Orion-Tr to keep the 12V nav lights and VHF happy, and the only thing I'd add is don't overlook the input voltage range if your 48V bank ever sags under heavy load, because the Orion-Tr will shut off if it dips below its minimum threshold and suddenly your bilge pump is having a very quiet moment at the worst possible time.