Voltage range and funcionality of remote switch in ORION TR DC/DC 12/24-20

Been running an Orion-TR Smart 12/24-20 on my narrowboat for about eighteen months now, stepping up from the bow thruster battery bank to the domestic bank, and I've been digging into the remote H/L terminal behaviour more than I expected to.

The manual states the remote pin accepts a voltage signal between 3.5V and 60V to enable the unit, or a simple short to ground to disable — but what it doesn't make entirely clear is how much current the input actually sinks, which matters if you're switching it via a relay coil output from a BMS or a BMV-712 relay.

My setup uses a Victron SmartShunt controlling a small relay, which then pulls the remote terminal low. Works reliably, but I did have a brief period where the Orion was toggling erratically — turned out to be a marginal contact on a cheap relay rather than anything inherent to the Orion itself.

A few things worth discussing:

• Does anyone know the exact input impedance on the remote terminal? The Victron datasheet is vague.
• Has anyone successfully driven it directly from a BMS logic output (3.3V or 5V GPIO-level signal) rather than a full 12V switched line?
• Any experience with using the two-wire Engine Detection feature as an alternative to the remote terminal entirely?

I suspect the Engine Detection route via the VE.Direct port and Victron Connect is actually cleaner for most narrowboat or static caravan installations, especially if you're already running a GX device. Curious what others are doing — particularly if you've got non-Victron BMS units in the mix.

@PN_Camper the remote H/L terminal on the Orion-TR Smart is one of those things that catches people out. From my own fiddling with one on a shepherd's hut build, the remote pin is looking for roughly 3.5V minimum to register as a HIGH (enable) signal, and it'll happily accept up to the full input voltage.

Worth knowing — it's not a simple on/off switch to ground like some older DC-DC units. It expects a positive signal, not a pull-down.

If you're triggering it from a VSR output or a ignition line, you'll generally be fine. Where it gets fiddly is if you're trying to use a dedicated switch wired incorrectly.

The Victron manual does actually document this reasonably well in the technical specs section — page varies by firmware revision though, annoyingly.

Great thread @PN_Camper. One thing worth adding to what @DefenderSolar mentioned — the H/L terminal on the Orion-TR Smart will accept anywhere from around 3.5V up to your input voltage as a "high" signal, so it's quite flexible in practice. On my own setup I've got it triggered directly from a GPIO pin on a Raspberry Pi (3.3V logic) via a simple transistor, which works a treat. Worth noting though that if you're using a relay or switch to pull it high, make sure you're not floating the terminal when "off" — tie it low to GND rather than just leaving it disconnected, otherwise you can get spurious triggering. Victron's own documentation is a bit vague on this point but it's caught a few people out on the Victron Community forum too.

Ran into this exact rabbit hole myself when I first wired up my narrowboat. Spent an embarrassing afternoon convinced my Orion-TR Smart was faulty before realising I'd wired the remote terminal to a switch that was floating rather than pulled properly to ground.

Worth mentioning — if you're triggering it from an ignition signal or a BMS allow-to-charge line, make sure your reference voltages actually match. I used a cheap relay to translate my engine management signal because the voltage levels were playing silly beggars with each other.

Also @PN_Camper, Victron's own wiring diagrams for the Orion-TR Smart remote terminal are tucked inside the manual appendix rather than the main section, which is spectacularly unhelpful. VictronConnect app sometimes clarifies things the paper manual glosses over.

Good timing on this thread — I went through exactly this when I was wiring the cabin build and then again sorting EV charging logic off-grid.

One thing nobody's mentioned yet: if you're pulling the H/L signal from something like a BMS aux output or a relay driven by a Victron MPPT load output, double-check the actual voltage the signal sits at under load. I had a relay that read 12.4V open-circuit but drooped to under 7V once everything was connected. Orion saw it as a floating line rather than a valid high signal.

Stuck a cheap multimeter on it whilst the circuit was live and the penny dropped immediately. Simple fix — either a stronger relay or a pull-up resistor depending on your source.

The Victron manual quotes that 7V minimum threshold but real-world noise on a boat makes the margin tighter than you'd expect.

Really glad this thread is getting some traction — narrowboat DC-DC setups are underrepresented here compared to van builds, so good to see the specifics being documented properly.

One thing I'd add that hasn't been mentioned yet: if you're using the remote terminal to trigger from an ignition-style signal, double-check your voltage at the terminal itself rather than at the source. I lost an afternoon to a significant volt drop across a long run on my van conversion before I realised the Orion was seeing 10.8V when the source was a solid 12.4V. Victron's own documentation is a bit sparse on the acceptable input range at that terminal specifically.

Also — @PN_Camper, welcome to the forum! Eighteen months of real-world data on a narrowboat install is genuinely valuable here. Don't be shy about posting your full wiring notes if you have them documented.