Orion 1400 XS with double alternately feeds: 12V & 24V

Been scratching my head over something similar for my shepherd's hut build and wondered if anyone's tackled this.

I'm running a 12V 100Ah Fogstar Drift LiFePO4 as my main bank, but I need to charge it from two different vehicle sources depending on where the hut is parked up — sometimes towed by a mate's 24V truck, other times hitched to my own 12V Land Rover.

The Victron Orion 1400 XS keeps coming up as a candidate. On paper it looks like it should handle both input voltages, but I can't find anyone who's actually run it in an alternating 12V/24V setup rather than a fixed one.

A few things I'm not clear on:

• Does the unit auto-detect input voltage properly, or do you need to manually reconfigure it each time you swap sources?
• Are there any BMS compatibility issues to watch for when the input voltage jumps around between sessions?
• Would a single unit cover both scenarios, or am I better off with two dedicated units and a changeover switch?

I know Victron's documentation is generally solid but it doesn't seem to address this specific use case directly. Wondering if anyone running a multi-vehicle touring setup — van conversions, mobile shepherd's huts, that sort of thing — has practical experience here rather than just spec-sheet answers.

Would really appreciate real-world input before I commit to buying.

@EwanChapman the Orion-Tr Smart DC-DC chargers from Victron are your friend here. The isolated versions will handle the voltage step-up/step-down between a 24V alternator feed and your 12V Fogstar bank without any backfeed issues.

Worth noting though — if your alternator source is genuinely 24V, size the Orion correctly. The 24/12-20A unit gives you 240W throughput which is decent for a shepherd's hut draw, but the 30A version exists if you're pushing harder loads.

One critical thing with LiFePO4 and DC-DC chargers: make sure engine detection is properly configured. The Orion Smart units support this via voltage threshold or a dedicated wire — don't rely purely on voltage sensing with lithium, you risk partial cycles confusing your BMS.

What's your alternator source — vehicle feed or a dedicated generator?

@OldSparky52 is on the right track with the Orion-Tr Smart isolated.

Worth noting though — if your 24V source is a vehicle alternator, make sure you're using the engine detection feature properly. Caught me out on my cabin build; it was pulling from the alternator when the engine was off and slowly draining things.

Also double-check your input voltage range. The 24V to 12V Orion-Tr Smart handles 18–35V input, so a healthy 24V bank is fine but watch for voltage sag under load.

One thing I'd verify before buying: does the Fogstar Drift's BMS communicate with the Orion via VE.Direct or are you relying on standalone mode? Mine runs standalone without issues but networked is cleaner if you've got a Cerbo GX already in the mix.

@EwanChapman just don't forget to set the charge profile to LiFePO4 on the Orion — Fogstar Drift cells are fussier than your average flooded lead-acid, and nothing ruins a shepherd's hut weekend faster than a thermal runaway you could've prevented with two minutes in VictronConnect.

@DodgySocket good shout on the charge profile — and worth adding that the Fogstar Drift's BMS will cut out if you push absorption too high. Stick to 14.2V max on the 12V side, not the default 14.4V some units assume.

One thing nobody's mentioned: if both sources (12V and 24V) might be live simultaneously, you'll want to think about sequencing. Two Orion-Trs feeding the same LiFePO4 bank at once is fine in theory, but check your total charge current doesn't exceed what the Drift's BMS will accept — the 100Ah version is rated 50A continuous charge IIRC.

Victron's VictronConnect app makes profiling the Orion-Tr Smart dead easy once you've got Bluetooth paired up.