Anyone else running Victron SmartSolar on a motorhome with a split charge relay — worth ditching the relay entirely?

Currently got a 200Ah Fogstar Drift LiFePO4 in my camper build alongside a 175W roof panel and a Victron MPPT 100/20. Split charge relay on the alternator feed has been doing the job but it's clunky and I'm losing voltage by the time it hits the battery.

Been reading about using a Victron Orion-Tr Smart DC-DC charger instead. Proper B2B charging, better for lithium, doesn't hammer the alternator. Seems like the obvious upgrade but at £120-150 it's not nothing.

Anyone made the switch from relay to DC-DC on a motorhome setup? Did it actually make a noticeable difference on charge times when driving? Wondering if the Orion 12/12-18 is enough or whether I'd need the 30A version for a 200Ah bank.

CamperAndrea | 847 posts

@NigeCampbell81 Honestly, yes — ditch the relay and grab a Victron Orion-Tr Smart DC-DC charger instead. The relay approach really struggles with LiFePO4 because the battery's flat voltage curve fools it into thinking it's full when it isn't, so you end up with poor alternator utilisation and potentially undercharged cells.

The Orion gives you proper CC/CV charging profiled for lithium, protects your alternator from the big inrush current that LiFePO4 can demand, and plays nicely within the Victron ecosystem — especially handy if you're already on SmartSolar with Bluetooth monitoring.

The 12/12-18 or 12/12-30 versions are the popular choices depending on how much alternator charging you actually want. Pairs brilliantly with that Fogstar Drift. I made the switch about 18 months ago and wouldn't go back.

LiamWalker | 312 posts

@NigeCampbell81 Completely agree with @CamperAndrea on the Orion-Tr Smart — it's a proper game changer for LiFePO4 setups. The big thing people overlook is that a standard split charge relay just dumps alternator voltage straight at your lithium, which your Fogstar Drift really won't thank you for long-term. The Orion gives you proper CC/CV charging with profiles suited to LiFePO4, and the isolated version means no nasty feedback loops between your starter and leisure batteries. I've got the 12/12-30 in my Transporter build and it's rock solid. Also worth knowing you can network it with your SmartSolar via Bluetooth and monitor everything through the VictronConnect app together. Only caveat — check your alternator isn't smart/variable voltage (common on newer Euro 6 vehicles), as that needs a bit more consideration before fitting.

Squib82 | 1,203 posts

One thing worth flagging that I haven't seen mentioned — if your van has a smart alternator (variable voltage regulation, common on post-2015 Euro6 engines), a standard split charge relay can actually damage the alternator over time by presenting too low an impedance. The Orion-Tr Smart handles this properly through its bulk/absorption profile.

Running a similar setup on my own motorhome — Victron MPPT 75/15 feeding a 100Ah LiFePO4 — and the DC-DC charger also means your lithium isn't fighting the starter battery for charge priority. The relay doesn't know or care; the Orion does.

Check your engine specs before assuming the relay is "doing the job" — it might be, but it might quietly be causing grief you won't notice until the warranty's up.

DorsetExplorer | 634 posts

@NigeCampbell81 welcome to the forum, great first post and a solid setup to start with! 👋

@Squib82 raises the smart alternator point which is massive — my Transit base had one and it was killing my old relay setup. Switched to the Orion-Tr Smart 18 months ago and honestly it transformed the whole system.

One thing nobody's mentioned yet — the Orion pairs brilliantly with your SmartSolar via the VE.Smart network. Both devices share data over Bluetooth and the charging becomes properly coordinated. Your Fogstar Drift will thank you for it, LiFePO4 really benefits from the precise charge profile rather than whatever a dumb relay chucks at it.

Keep asking questions — this community is brilliant for camper builds 🚐

Glen1961 | 847 posts

@NigeCampbell81 Good shout from @Squib82 about smart alternators — worth checking your van's ECU behaviour before committing to anything. One thing nobody's mentioned yet: if you do go the Orion-Tr Smart route, make sure you're using the engine-running detection properly rather than just relying on the voltage threshold trigger. On some vans the leisure battery voltage alone can fool it into thinking the engine's running when it isn't. Set it up via the VictronConnect app and take your time with the charge profile settings to match your Fogstar's specs — Fogstar publish recommended parameters on their site which is handy. Your MPPT and the Orion will play nicely together too once everything's dialled in. Cracking little setup overall, should serve you well.

MasterProject | 89 posts

Slightly different use case here — I run a Victron Orion-Tr Smart DC-DC 12/12-30 on my narrowboat and the difference compared to a basic relay is night and day. The Orion handles the LiFePO4 charge profile properly rather than just slamming alternator voltage straight at the battery.

For your camper setup @NigeCampbell81, the same logic applies — the 30A model is probably overkill for a single leisure battery but the 18A would pair nicely with your existing MPPT. Both sources then feed the Fogstar correctly without fighting each other.

Worth noting the Orion-Tr Smart also integrates with Victron's VictronConnect app, so you can monitor charging from both sources in one place. Given you've already got the Victron ecosystem going with the SmartSolar, it makes sense to keep it all talking together.