Orion Smart TR 12/24 DC-DC Charger with VE.Bus BMS V2 current output issue

Been wrestling with something similar on my tiny house setup so figured I'd throw this out there.

Running a pair of Orion Smart TR 12/24-15 units in parallel to charge a 24V Fogstar Drift 200Ah lithium bank from a 12V vehicle-side source. The VE.Bus BMS V2 is supposed to handle charge disconnect cleanly via the remote H/L port, but I'm seeing the Orions behave oddly — they'll occasionally restart mid-charge cycle rather than tapering off gracefully when the BMS signals them.

Suspect it's the BMS pulling the remote line low too aggressively and the chargers interpreting it as a fault rather than a controlled stop. Victron's own docs are a bit vague on the exact voltage thresholds for the H/L input on these units when you've got multiple chargers daisy-chained on the same signal wire.

A few things I'm considering:

• Adding a small buffer resistor on the remote line
• Checking whether the VE.Bus BMS V2 firmware is current (mine was on an older version)
• Moving to VE.Smart networking to co-ordinate the units rather than relying purely on the hardwired remote

Has anyone got 3+ Orions playing nicely with a VE.Bus BMS V2? Curious whether the current output figures you're seeing match what the Victron app reports — I'm getting a noticeable discrepancy between actual measured output (clamp meter) and what VictronConnect shows across both units combined.

Would love to know if this is a known calibration quirk or something worth raising with Victron support directly.

@GoldenMaker the post got cut off but I think I know where you're going with this...

Classic issue with the VE.Bus BMS V2 — the allow-to-charge signal on the remote L port needs to be wired correctly to both Orions when running them in parallel. Easy to miss that each unit needs its own connection rather than daisy-chaining.

Also worth checking:

• Engine detect threshold set properly for your source battery
• Both units on the same firmware version (Victron Connect → update if not)
• That you've actually enabled parallel mode in settings, not just physically wired them

What symptoms are you seeing exactly? Low output current, or is one unit dropping out completely? Makes a difference for diagnosis.

@GoldenMaker my garden office has the exact same setup and the VE.Bus BMS V2 essentially becomes a very expensive traffic warden — constantly telling your Orions to stop when they were just getting going 🚦

The LOAD DISCONNECT output on the BMS needs wiring to the REMOTE ON/OFF on both Orions, otherwise they'll just ignore the BMS's polite requests to throttle back during cell balancing events.

Check your Victron Connect app — if you're seeing the units flip between Bulk and Off repeatedly, that's your culprit right there.

@GoldenMaker @CE_Builds both got cut off mid-sentence which is honestly more suspenseful than anything on telly right now 🍿

But yeah — ran into this on the narrowboat with a single Orion Smart TR and the VE.Bus BMS V2 doing its best impression of a permanently red traffic light. Culprit was the allow-to-charge signal not being wired through to the remote L port properly. Once I sorted that, the Orion actually did what Victron's marketing department promised it would.

Worth checking your VE.Bus BMS V2 load disconnect vs charge disconnect outputs — easy to mix them up and then wonder why your Fogstar sits there sulking at 60%.

Ran into this exact scenario on the narrowboat last spring. Had a single Orion Smart TR feeding a Fogstar 200Ah and the VE.Bus BMS V2 kept throttling current down to almost nothing — Victron Connect showing the unit hunting around like it couldn't decide what it wanted to do.

Turned out my VE.Bus BMS V2 charge disconnect wire wasn't going to the Orion's remote on/off pin correctly. Once I sorted that, the Orion respected the BMS signals properly rather than second-guessing them.

@Stu1991 — worth checking whether yours is wired to load disconnect by mistake, which is a surprisingly common mix-up on installs.

Also, are both your parallel Orions on the same VE.Smart network? If they're not properly networked together they can fight each other on current limiting, which looks identical to a BMS comms problem.

Haha @Stu1991 fair point, we're all on the edge of our seats waiting for these sentences to finish!

@GoldenMaker to add something actually useful - with the VE.Bus BMS V2 controlling the remote H/L pins on your Orions, make sure you've got the charge disconnect wired to the remote pins rather than relying on the Orion's own BMS communication. The TR units in parallel can sometimes fight each other if the remote signals aren't arriving simultaneously, causing one unit to briefly see the other's current as a load. Worth checking whether your issue is intermittent or consistent - intermittent usually points to the remote wiring, consistent often suggests something in the algorithm settings. What firmware version are you running on the Orions? There was a meaningful update a while back that improved parallel coordination.

@GoldenMaker yeah the truncated posts are killing me too but I can piece together what's likely happening here.

Parallel Orions feeding into a Fogstar with VE.Bus BMS V2 — classic current limiting headache. The BMS V2 sends a charge disconnect signal and the Orions can get a bit confused about when to back off, especially if they're not both on the same firmware.

Few things worth checking:

• Are both units identical firmware? Mixed versions cause weird handshaking issues in parallel
• Is your BMS V2 actually wired to the Orion's remote L/H port correctly?
• Check your Victron Connect logs — the charge current graph will show if it's dropping out intermittently or throttling properly

Mine did something similar until I realised one unit was running older firmware. Night and day difference after updating both.

Finish your post though mate, we're all guessing in the dark here 😄