Anyone else running a Victron Orion-Tr Smart 12/12-30 in parallel — how are you handling the load sharing?

So I've finally got two Orion-Tr Smart 30A units wired up in parallel on my Transit camper build, pulling from a 110Ah AGM starter battery into a 200Ah lithium leisure bank. Done it mostly because a single 30A wasn't keeping up with the fridge and general loads on longer drives — made sense on paper to double the input capacity.

The thing is, I'm noticing one unit consistently running warmer than the other, which makes me think they're not splitting the load evenly. Both are on the same firmware (v1.17), both set to the same absorption and float voltages (14.4V / 13.6V), and the cable runs to the bus bar are as close to equal length as I could manage — roughly 400mm each in 16mm² cable.

I've had a dig through the Victron docs and there's a note about parallel operation being supported but not explicitly "load balanced" — which, fair enough, but I wasn't expecting quite this much of a temperature difference. The warmer one is sitting around 55–58°C under load while the other barely gets past 42°C. Both are in reasonable airflow, mounted vertically on the same panel.

Has anyone actually got a balanced parallel setup running reliably, or is this just the nature of the beast with these units? Wondering if it's worth swapping to a single 50A unit instead and calling it done.

Declan1985 | 47 posts

@DuctTapeDave62 Nice setup! One thing worth knowing with the Orion-Tr Smart in parallel — they don't actually communicate with each other like the Multiplus units do, so you won't get true load sharing in the coordinated sense. Each unit operates independently based on its own input voltage sensing. What you'll likely find in practice is they're roughly balanced but not perfectly so, especially if your cable runs aren't identical lengths and gauges.

Worth keeping an eye on temperatures on both units early on, as any significant imbalance will show up there first. Also make sure your engine-running detection thresholds are set identically on both via the VictronConnect app, otherwise you might get one kicking in before the other. What firmware version are you running? There were some improvements to the algorithm a while back that helped consistency.

PaddyFox | 203 posts

@DuctTapeDave62 Good shout going parallel — 60A combined is a decent chunk for keeping that lithium bank happy on longer runs. One thing I'd flag that hasn't been mentioned yet: make sure both units are on the same firmware version before you do anything else. I had a nightmare situation where mine were behaving slightly differently under load because one had auto-updated and the other hadn't. Symptoms were subtle but the VictronConnect app was showing inconsistent current readings between the two. Quick firmware sync sorted it completely. Also worth double-checking your input wiring is as equal in length and gauge as possible between both units — any resistance difference will skew the load sharing more than you'd expect. How are you triggering the remote on/off, engine sensing or the dedicated input wire?

ShaunKelly87 | 118 posts

@DuctTapeDave62 One thing I'd keep an eye on is whether both units are seeing identical input voltage — even a small difference in cable runs or connection resistance can cause one unit to shoulder more of the load than the other. Worth checking with a multimeter at each unit's input terminals under load rather than just at the battery. I ran a similar parallel setup on my Sprinter and found my longer cable run was dropping enough to make one unit throttle back noticeably. Matched cable lengths and crimped lugs sorted it. Also make sure your VE.Direct or Bluetooth configs are truly identical across both units, particularly the engine shutdown voltage — you don't want one cutting out before the other and leaving the second one doing all the heavy lifting on its own.

WezWhite72 | 341 posts

@DuctTapeDave62 Worth flagging — when I ran two Orion-Tr Smarts in parallel on my cabin battery bank (feeding a 280Ah Fogstar Drift LiFePO4), I found the VE.Direct networking between units genuinely matters here. If you're not linking them via the Victron Connect app and syncing their engine-detection thresholds to identical values, you can end up with one unit kicking in slightly before the other under load cycling. Not catastrophic, but it means one unit consistently runs harder than the other and thermal wear becomes uneven over time.

Also — check your input cable runs are matched length and gauge. Even a small resistance differential between the two input feeds will cause unequal current draw. I used 35mm² throughout and kept both runs within 10cm of each other in length. Sounds pedantic but it made a measurable difference on my clamp meter readings.

BurnWalker | 89 posts

Running a single 30A on my narrowboat and honestly questioning whether I should've gone parallel from the off. One thing nobody's mentioned — are you syncing the charge profiles through VictronConnect or just leaving both units to do their own thing? Because if they're not on identical absorption/float settings they'll fight each other more than you'd think. Had a similar mess with two mismatched units on a mate's static before he sorted the config.

Also, what's your alternator rated at? 60A draw on a Transit's standard alternator under load could be pushing it, especially at tick-over. Might be worth a VSR or checking the Victron docs on input current limits before you cook something.

SamKing | 203 posts

One thing nobody's mentioned yet — make sure you've got both units configured as "engine running only" mode in VictronConnect if you're bothered about draining your starter battery. The alternator detection threshold on each unit can drift slightly independently, so one might kick in a touch before the other. Not a massive issue at 30A but worth knowing. Also double-check your cable runs to each unit are equal length and same gauge — imbalanced resistance between them will cause one to work harder than the other over time. @BurnWalker honestly for a narrowboat a single 30A is probably fine unless you're running serious loads!

NeilAllen | 267 posts

Good setup @DuctTapeDave62 — one thing I don't think's been mentioned yet is making sure your input cable runs to each unit are as equal in length as possible. If one unit has a noticeably shorter run, it'll see slightly less resistance and end up shouldering more of the load over time, which can skew things even if the units are configured identically in VictronConnect. Might sound fussy but over a long motorway run it does matter. Also worth confirming you've got them both set to the same algorithm for your lithium bank — easy to accidentally have one on a different absorption voltage if you configured them separately. What firmware version are you on? There was a batch a while back with some quirks around parallel current sharing that a firmware update sorted fairly cleanly.