Orion XS #67 BMS connection lost

Had a similar headache with my static van setup last summer — Cerbo GX, Smart Lithium 200Ah (Victron), and an Orion XS 30 feeding from a vehicle alternator. All connected via VE.Direct and VE.Can respectively.

What I found was the Cerbo periodically throwing "BMS connection lost" warnings on the Orion XS, even though physically nothing had changed. The Orion would drop into a safe state and stop charging — obviously not ideal when you're relying on that as your primary charge source mid-trip.

A few things worth checking:

• VE.Can termination — easy to overlook, but both ends of the CAN bus need 120Ω terminators fitted. Missing one caused me grief for about three days before I spotted it.
• Network instance conflicts — if you've got multiple devices on VE.Can, check for duplicate instances in the Cerbo's device list. I had a clash between the Lynx Shunt and the BMS that caused intermittent dropouts.
• Firmware versions — the Orion XS and Lynx Smart BMS need to be on matching compatible firmware, not just individually "latest." Victron's release notes sometimes flag this.

I ended up doing a full VE.Can bus reset (remove all devices, re-add one at a time) and that cleared it for good. Bit of a faff but worth the methodical approach.

Is yours dropping out under load, or randomly at rest? That might point toward a power supply issue to the Cerbo rather than a comms fault.

Curious whether others in the UK have seen this more since the later Orion XS firmware pushed out earlier this year — there was a

@EdHamilton the "connection lost" fault on the Orion XS is almost always a VE.Can termination issue rather than a genuine comms failure. Make sure you have exactly two 120Ω termination resistors on the CAN bus — one at each physical end of the chain. Victron's own Cerbo GX has a built-in terminator you enable via a jumper, so folk often accidentally double-up or miss it entirely.

Also worth checking: on GX firmware v3.00+, the Orion XS needs its own unique VE.Can device instance. Navigate to Settings → VE.Can → Devices and verify there's no instance conflict with your Smart Lithium BMS.

On my narrowboat I had identical symptoms until I realised the RJ45 boot on one VE.Can cable was slightly proud of the socket — barely seating the contacts. Swap cables methodically before assuming the Orion itself is faulty.

@DevonDweller is right about termination, but don't overlook the 120Ω resistor jumpers on the Cerbo GX — VE.Can needs one at each physical end of the bus, and the Orion XS #67 specifically has a known firmware quirk where it drops off the bus if the termination impedance reads outside ~108–132Ω total.

Quick checklist before assuming hardware failure:

• Measure bus impedance with power off (should be ~60Ω across the two terminators in parallel)
• Check VE.Can cable isn't shared with other noise sources near the alternator feed
• Flash the Orion XS to latest firmware via VictronConnect — there were silent fixes around this in recent builds

My Victron Smart Lithium/Cerbo setup threw identical ghosts until I replaced a £2 RJ45 with a proper shielded VE.Can cable — embarrassingly simple fix, annoyingly expensive lesson.

@OldSailor @DevonDweller both solid points — had this exact nightmare on my motorhome last spring and spent three days convinced my Fogstar battery had gone rogue before realising the VE.Can cable I'd bought off eBay was basically a fancy piece of string with RJ45 connectors glued on for decoration 🔌

@EcoFlowMaster three days — rookie numbers, I spent a fortnight on mine before realising the VE.Direct cable I'd bought off a well-known auction site was wired with the TX/RX lines swapped.

Worth checking: if you've confirmed termination and the Cerbo jumpers, pull the VE.Can network completely down to just the Orion XS and Cerbo — no other devices — and see if the fault clears. Sometimes a flaky SmartShunt or MPPT elsewhere on the bus is hammering the network with errors and the Orion XS gets the blame.

Also, Victron Connect will show you the VE.Can error counter on the Cerbo; if that's climbing fast you've got a rogue device, not a termination issue. Static caravan setup sorted now, but only after I'd replaced half the loom.