Victron Orion-Tr Smart 30A vs going bigger — worth the extra on a narrowboat?

Running a 200Ah lithium bank (Fogstar Drift) on my narrowboat and currently using a cheap 20A B2B charger off the alternator. It's fine-ish but I'm losing loads of potential charging time on longer cruises. Been eyeing up the Victron Orion-Tr Smart 30A isolated but wondering if I should just jump straight to the 50A version.

The 30A pulls around 360W from a 12V system which feels sensible, but my alternator is a bog-standard 70A unit and I'm a bit nervous about cooking it on extended runs. Has anyone actually run a 50A B2B long-term off a similar-sized alternator without issues?

Also curious about the engine shutdown detection on the Orion Smart — does it actually work reliably over Bluetooth or do people end up hardwiring the D+ connection anyway? Seen mixed things on here and on the Victron community forums.

Basically deciding between spending ~£180 for the 30A or stretching to ~£280 for the 50A. Not a massive difference if the 50A genuinely fills a 200Ah bank meaningfully faster during a 3-hour cruise.

@PanelKate the Orion-Tr Smart 30A is genuinely worth it on a narrowboat — the Victron app integration alone is worth paying for. You can see exactly what's happening with your charge profile and tweak it properly for the Fogstar's lithium chemistry.

That said, if your alternator is older or on the smaller side (common on canal boats running Beta or Vetus engines), pushing more than 30A through it for extended cruising can cause issues. Check your alternator rating first.

One thing people overlook — the isolated version is essential if your engine and domestic banks share a negative, which most narrowboats do. Don't cheap out on that.

I ran a 20A non-Victron unit for two seasons and the difference when I swapped was immediately obvious on cloudy days when solar contribution is minimal.

Has anyone actually compared the Orion-Tr Smart 30A vs the 50A on a similar bank size? I'm in a slightly different situation (garden office rather than narrowboat) but weighing up the same decision for EV charging top-ups via my van alternator.

Specifically wondering:

• Does the 50A cause any issues with smaller alternators on older engines?
• Is the Bluetooth monitoring genuinely useful day-to-day or just nice at setup?

I went Victron on my solar side (MPPT 100/30) and the ecosystem integration is brilliant, so the Orion-Tr Smart makes sense — just not sure if the 30A would bottleneck things with a 200Ah+ bank once I eventually scale up.

@NickHughes curious what size alternator you're running alongside the 30A?

@KenCross ran almost exactly this comparison on my boat last summer. Had the 30A installed for two years, then upgraded to the 50A when I rewired the engine bay.

Honest verdict: on a 200Ah bank the 30A is plenty. You're looking at roughly 360W input — the bottleneck shifts to your alternator temperature long before you're wishing for more amps. My old Beta 43 was already getting warm on extended cruising with the 30A pulling hard.

The 50A made sense for me because I'd added a second 200Ah battery and was doing longer moorings where engine hours were limited.

@PanelKate — if you're sticking with that single Fogstar Drift, save the money and get the 30A. Put the difference toward a decent alternator temperature sensor instead. Victron's own monitoring will tell you everything you need to know.

Hey @KenCross and @BoatIan — great timing on this thread. One thing worth factoring in that I haven't seen mentioned yet: your alternator health matters a lot when sizing up. Jumping to the 50A on an older engine (common on narrowboats!) can stress a tired alternator pretty hard, especially on tickover. The 30A is a gentler ask. That said, if you've got a decent modern engine doing regular cruising stints, the 50A pays for itself quickly on a 200Ah bank — you're filling that battery meaningfully rather than just topping it off. @PanelKate, also worth checking whether your current alternator has a smart regulator or is dumb — makes a real difference to how aggressively you want to pull from it.