Anyone else running a Victron Orion-Tr Smart 12/12-30 alongside a split charge relay — worth ditching the relay entirely?

So I've finally got round to upgrading the leisure setup in my Transit Custom and I'm trying to decide whether to keep the old split charge relay or just let the Orion-Tr Smart do all the work on its own. At the moment I've got both running side by side, which feels a bit daft, but I wanted a fallback while I got my head around the Victron kit.

The Orion is set up in non-isolated mode pulling from a 110Ah AGM starter battery and charging a 200Ah lithium leisure bank. I've got it configured via the app with the engine detection threshold sitting at 13.2V, which seems to kick in reliably enough once the alternator spins up. The relay is a basic 140A unit that was already in the van when I bought it, so it's not costing me anything to keep it there — but it does feel like it's fighting the Orion a bit given they're both trying to manage the same circuit.

Has anyone actually measured whether the relay is doing anything useful once the Orion is properly dialled in? I'm a bit worried about the relay slamming the full alternator output onto the lithium bank during those first few seconds before the Orion cuts in, especially in cold weather when the internal resistance is higher on the cells. My alternator is only a 120A unit so I don't want to be hammering it either.

Chopper84 | Posts: 847

@PeteDixon89 Ditch the relay, honestly. The Orion-Tr Smart renders it completely redundant and actually does a proper job of it. The relay doesn't care about your starter battery voltage — it'll happily drag it down if your alternator's working hard. The Orion isolates everything properly and charges your leisure battery in controlled stages rather than just dumping raw alternator voltage across it.

Big thing people miss — if you've got a smart alternator (which the Transit Custom almost certainly has), a relay is basically useless anyway. The Orion handles the variable voltage from those BMS-controlled alternators properly via its special mode setting.

Keep the wiring tidy, set your engine runtime detection threshold sensibly, and you're sorted. No reason to have both running simultaneously cluttering up your install.

EwanPowell92 | Posts: 312

@PeteDixon89 Agree with @Chopper84 on ditching it, but worth adding why — the Orion-Tr Smart uses proper DC-DC conversion with voltage regulation, so your leisure battery gets a genuine charge profile rather than just whatever the alternator's putting out minus cable losses. The split charge relay was always a bit of a bodge really. One thing to double-check though — make sure you've got the non-isolated version if your Transit Custom shares a common chassis earth between both batteries, otherwise you'll run into earthing issues. Also worth enabling the engine detection feature in the VictronConnect app rather than relying on ignition switching, as it reads alternator voltage directly. Much cleaner setup overall.

TorDweller | Posts: 1,204

Running a very similar setup on my narrowboat — Orion-Tr Smart 12/12-30 feeding a Fogstar Drift 100Ah lithium. What nobody's mentioned yet is the alternator protection angle.

With a split charge relay, your alternator sees the full hunger of a depleted lithium bank and can cook itself over a long cruise. The Orion-Tr's DC-DC conversion naturally buffers that draw, keeping things sensible on the alternator side.

On a narrowboat this is critical — marine alternators aren't cheap and you're running the engine hard anyway just to move. I'd imagine a Transit Custom sits in similar territory with stop-start systems too; the Orion handles that gracefully whereas a relay just slams connections open and shut.

Relay's been sat in a box in my engine room for two years now. No regrets.

RetiredChef26 | Posts: 2,156

Good thread this. One thing nobody's mentioned yet — with the Orion-Tr Smart running solo, you get proper charge profiling rather than the relay's dumb "voltage follows starter battery" approach. That's particularly valuable if you're running lithium on the leisure side, since you can dial in the charge parameters precisely and avoid pushing inappropriate voltages through.

Also worth considering from a fault-finding perspective: the Bluetooth monitoring through VictronConnect means you can actually see what's happening in real time. When something goes wrong with a relay setup you're often just guessing.

@TorDweller — curious what you're seeing on charge times with the Fogstar Drift compared to a traditional AGM? I switched my camper to lithium last spring and the Orion handles it beautifully.

Just keep the relay out of the circuit entirely once you're happy with the Orion setup, @PeteDixon89. No point having conflicting systems.