Dimensionnement Orion-TR Smart

Been going through a similar sizing exercise for my tiny house setup, so this feels relevant.

I've got the Victron Orion-TR Smart 12/12-30A (360W) on my shortlist for charging a 200Ah lithium bank from a vehicle alternator whilst the van is running. The isolated version is the obvious choice when you've got a smart alternator — pretty much essential these days to avoid confusing the BMS or the alternator's voltage sensing.

One thing worth thinking carefully about is cable run length. The 30A unit is great on paper, but if you're running 4–5 metres of cable between the starter battery and the aux bank, you want to be calculating volt-drop properly. I'd be looking at 16mm² minimum, possibly 25mm² depending on the run. The Victron docs are fairly clear on this but it's easy to underestimate.

Also worth considering: are you pairing it with a Victron SmartShunt or BMV-712? The Orion can pull charge data via Bluetooth into VictronConnect, which makes monitoring the whole system much cleaner — especially when you've got a lithium like the Ultimatron (or similar LiFePO4 cells from Fogstar etc.) that needs tight management.

My actual question for the thread: has anyone found the 30A unit sufficient for a 200Ah lithium, or did you end up running two in parallel? I'm wondering whether it's worth jumping straight to the 18A + 18A parallel approach for redundancy, even though it costs more upfront.

@LDVConvert the 30A Orion is a solid pick for that use case. Few things worth checking:

• Make sure your alternator is rated for sustained load — the Orion draws continuously, unlike a solar controller. Older or smaller alternators can overheat
• Enable the alternator protection feature in VictronConnect — adds a small delay before it ramps up
• 30A into 200Ah lithium is a reasonable ratio, won't stress the cells
• If you're running engine-off loads too, pair it with a proper BMS that can signal the Orion to shut down

I've got the smaller 18A version on my boat feeding a Fogstar 100Ah — works a treat. The Smart version's worth the premium for the Bluetooth monitoring alone.

What's your donor battery/alternator setup?

@LDVConvert one thing I'd add that often gets overlooked — check your cable run length between starter battery and the Orion input. Voltage drop on a long run will throttle your actual charge current significantly, sometimes knocking 20-30% off real-world performance.

I run a 30A unit in my own setup and sized up to 10mm² cable on a ~4 metre run to keep drop under 0.5V. Victron's own cable sizing tool is worth running before you commit.

Also worth confirming whether your van's alternator is smart/variable voltage — many post-2015 Euro 6 LDVs use alternator management systems that the Orion handles well in standalone mode, but you need to set the input voltage threshold correctly or it'll cycle on and off annoyingly.

Good point from @CE_Builds and @Bazza60 on the alternator and cable checks.

One thing I'd add from my boat installation — the Orion-TR Smart works brilliantly but don't overlook the input voltage drop threshold. If your alternator voltage sags under load (common with older units), the Orion can disconnect mid-charge. Victron's Connect app lets you adjust the input lockout voltage, which saved me a lot of head-scratching.

Also worth knowing: the isolated version is strongly recommended for any vehicle or marine setup where you can't guarantee a shared negative. Costs a bit more but avoids all sorts of ground loop grief.

For 200Ah lithium, the 30A unit is perfectly reasonable — I ran a similar bank on mine for ages before upgrading to the 18A→30A config via firmware, which the newer units support.

Good points all round already covered.

One thing worth adding — the Orion-TR Smart has engine detection built in via the input voltage threshold, but if you're running a modern van/tiny house with smart alternators (Euro 6 era stuff especially), you'll want to double-check it's actually triggering correctly. Some setups need a bit of tweaking on the detection voltage in VictronConnect.

Also worth knowing: you can daisy-chain two units if you ever need more charge current later — handy if your 200Ah bank grows. I ran a single 30A on my garden office build for a while before adding a second.

The isolated version is the one to go for if your chassis is shared earth — avoids ground loop headaches.