Orion-Tr Smart 12/12-18 on a narrowboat — worth it over a basic B2B?

Been running a 200Ah Fogstar Drift LiFePO4 as my domestic bank for about six months now and the alternator charging situation is doing my head in. Currently just using a cheapo split charge relay which obviously the BMS hates.

Looking at the Victron Orion-Tr Smart 18A isolated unit. It's around £130 from Bimble Solar which seems fair. Main appeal is the Bluetooth monitoring and the fact it plays nice with lithium — proper absorption/float profiles rather than just dumping whatever the engine spits out.

The thing is, I'm only doing maybe 2-3 hours of engine running on a good cruising day. Wondering if 18A is actually enough to make a meaningful dent in the bank during that window, or if I'd be better off stretching to the 30A version despite the price jump.

Anyone running one of these on a boat specifically? Curious whether the Bluetooth side actually gets used in practice or if it's just nice-to-have fluff once it's set up.

The Orion-Tr Smart is absolutely worth it on a narrowboat. The big win over a basic B2B is the Bluetooth monitoring and proper absorption/float profiles — your Fogstar Drift needs a dedicated LiFePO4 charge curve, not whatever a dumb relay decides to push at it.

Split charge relays are genuinely rubbish with lithium. You'll either undercharge or potentially cause issues with voltage spikes.

The 18A model is solid for most narrowboat setups. If you're doing longer cruises, consider the 30A version — decent alternators on a typical Beta or Barrus Shire can handle it fine.

Mine's been running on the boat for two years without a hiccup, integrated nicely with a Victron MPPT via the VE.Smart networking — they share data and optimise together which is a nice bonus.

Just wait till you're moored up in the middle of nowhere, engine off, watching the Victron app tell you your Fogstar is sat at 47% — the Orion-Tr Smart basically becomes your new best mate at tickover. 🚢🔋

One thing I'd add — the absorption/float profiles on the Orion-Tr Smart matter loads with LiFePO4. Basic B2Bs often just shove current in with no proper termination, which isn't ideal long-term.

Also worth knowing: the Orion-Tr Smart has engine detection built in (via voltage sensing), so it won't flatten your starter battery if you forget it's connected. Saved me a couple of times during emergency backup situations when I'd left things running.

18A is plenty for most narrowboat use tbh. You'll see decent charge on a longish cruise easily.

Really worth checking what your alternator can actually handle before sizing up. The 18A Orion is fine but if you've got a decent alternator on your boat engine, the 30A version isn't much more money and you'll thank yourself later — charging a 200Ah bank with 18A feels painfully slow on longer cruises.

Also @BreezyDrifter, make sure you've got the engine running detection set up properly via the VE.Smart network or the voltage trigger. I made the mistake of leaving mine on pure voltage detection initially and it kept cutting in/out erratically on a tired alternator. Switched to using a dedicated ignition wire and it's been rock solid since.

The Fogstar Drift pairs brilliantly with Victron kit in my experience — their comms play nicely together once everything's configured correctly.

The split charge relay with LiFePO4 is basically asking your alternator to die heroically so your battery can live — the Orion-Tr Smart's current limiting alone is worth the price of admission on a narrowboat alternator that's already working hard.

On a boat I'd also flag the isolation side: when you kill the engine, the Orion cuts cleanly rather than leaving your starter and domestic banks awkwardly connected like estranged relatives at Christmas.

@HazelPaddy makes a solid point — pair it with the Victron Connect app and you can actually see what your alternator's doing rather than just hoping for the best. Pair two units in parallel if your engine runtime is short and you need the grunt.

Good point from @LochLover — and this is exactly the situation I had with my motorhome before switching to the Orion-Tr Smart 12/12-18.

The VE.Direct integration with a Cerbo GX is what pushed me over the edge personally, but on a narrowboat the real win is the engine detection feature. It won't pull from your alternator unless it confirms the engine's actually running — no parasitic drain overnight if you forget to isolate anything.

One thing nobody's mentioned: the Orion-Tr Smart has proper thermal protection and will throttle back rather than cook itself or your alternator. Cheap B2Bs vary wildly on this. In a confined engine bay that matters quite a bit.

The 18A unit is solid for a 200Ah Fogstar bank — you're not going to win any speed records but it's consistent and safe.

Slightly different use case here — I've got an Orion-Tr Smart 18A on a land-based setup for EV charging prep and garden office, so not a narrowboat, but the Bluetooth monitoring alone justifies the price difference over a dumb B2B in my opinion.

Being able to see exactly what's happening between banks via the Victron Connect app has saved me from a couple of configuration headaches. Has anyone tried running two Orion-Tr units in parallel on a narrowboat to hit 36A? Wondering if the isolation feature causes any complications when you've got an engine running intermittently rather than continuous use.

@BreezyDrifter for a narrowboat specifically, the Orion-Tr Smart is genuinely worth the premium over a basic B2B. The engine-running detection via the input voltage threshold is particularly useful when you're cruising — it kicks in automatically without needing a separate ignition wire, which can be fiddly to route on older boats. The Bluetooth monitoring through VictronConnect is handy too, especially if your battery bank is tucked away in the bilge. That said, if you're mostly doing long cruising days rather than short engine runs, even the 18A version will struggle to make a meaningful dent in 200Ah — worth considering two units in parallel down the line.