Anyone else finding the Victron Orion-Tr Smart struggles to maintain 14.4V absorption on a long motorway run?

Picked up a 30A Orion-Tr Smart a few months back to charge my 100Ah lithium (a Fogstar Drift) from the van's alternator on my Transit Custom. Set it up with the engine detection threshold at 13.2V and it kicks in fine. Problem is, on a long A-road or motorway run I keep seeing it drop out of absorption early — it'll hit 14.4V for maybe 10-15 minutes then step down to float at 13.5V even though the battery is only showing 60-70% SOC on the Victron app.

I've had a poke around in VictorConnect and I can see the absorption time is set to "adaptive" by default. I've tried bumping the fixed absorption time up to 2 hours but honestly I'm not confident I've got the charge profile dialled in correctly for the Fogstar. Fogstar's own docs say 14.6V absorption and 13.6V float, which is slightly different to what Victron defaults to, so I've adjusted those figures — but still getting the early cutoff behaviour.

Has anyone run this specific combo or something similar? Wondering whether it's a wiring issue (I'm on 6mm² cable, about 1.8m run from the starter battery terminals), a profile setting, or whether the Orion just isn't well suited to longer bulk charges on a lithium without a proper BMS comms link. Any thoughts much appreciated.

Had the same with my setup charging the garden office batteries on longer runs. Worth checking your cable sizing first — voltage drop on the input side will throttle the output before anything else. What gauge are you running from the starter battery?

Also the Orion-Tr Smart will back off if it detects the alternator struggling (input voltage sagging). Transit Customs are notorious for having a fairly load-sensitive alternator. Try dropping your absorption to 14.2V — the Fogstar Drift is perfectly happy there and you'll stop the charger hunting.

One other thing: make sure engine detection is set properly so it's not switching in/out mid-run. That'll cause exactly the behaviour you're describing.

Really common one this, @JimChapman74. Worth having a look at your alternator's actual output voltage under load — many modern Ford Transit alternators run a smart charging profile and will deliberately drop output voltage once the ECU decides the battery is sufficiently charged. The Orion then simply can't maintain 14.4V if it's only seeing 13.6V or so coming in. You can check this with a multimeter directly at the alternator terminals while moving (or have someone else drive!). If that's the culprit, the Orion isn't at fault at all — it's just being starved upstream. Some folk have had success adjusting the engine detection threshold slightly but the root cause is usually the alternator behaviour rather than anything wrong with the charger itself.

Right, so I had exactly this drama with my Kangoo build last year. Turns out my alternator was a "smart" variable-voltage unit that backs off to around 13.6V once it thinks the starter battery is happy — which it does pretty quickly on a motorway cruise.

The Orion sees that sagging input and just... gives up on hitting 14.4V. Completely logical behaviour from it, annoyingly.

Worth jumping into the Victron Connect app mid-journey (passenger does it, obviously 😅) and checking the input voltage tab in real time. If you're seeing sub-13.8V coming in, that's your culprit — not the Orion itself.

Some Transit Custom alternators respond well to adding a small constant load elsewhere to keep them "thinking" they need to work harder. Bit daft, but it works.

Same issue crept up on my Transit-based garden office setup. Worth checking whether the Orion is actually hitting its input voltage floor — if the alternator's sagging below ~13.8V under load, the unit will throttle back automatically to protect the starter battery rather than push through to 14.4V absorption.

Quick test: grab a multimeter and measure directly at the Orion's input terminals while cruising at 2500rpm. If you're seeing anything below 13.5V there, it's a supply problem not the Orion itself.

Also — @KangooDream makes a fair point about smart alternators. Transit Customs post-2016 often run variable voltage. The Orion should handle that, but I had to bump my engine detection threshold up to 13.4V before mine stopped false-triggering into storage mode mid-journey.

Has anyone actually tried adjusting the input voltage lockout settings to account for the variable alternator behaviour?

On my Transit build I found the Orion was cutting in and out which masked whether absorption was truly being held. Logged it properly through the VictronConnect app over a couple of runs before I could see what was actually happening versus what I assumed was happening.

Also worth asking — what's your cable run length and gauge from the alternator/starter battery to the Orion input? I had a marginal voltage drop on mine that only showed up under sustained load on a longer motorway stretch, not on shorter runs.

@KangooDream — when you say variable voltage alternator, did you end up using the Orion in standalone mode or did you keep engine detection active?

Just to add to what @KangooDream and @VanKev are getting at — the Transit Custom's alternator is almost certainly an Eco Blue smart unit that drops output voltage intentionally to reduce load on the engine. What I've found helpful on my narrowboat's engine charging setup is enabling the Adaptive algorithm in the Orion's settings and bumping the input current limit down slightly, which seems to give the unit more headroom to regulate properly when input voltage wobbles.

Also worth connecting via Bluetooth and watching the live data during a run — you'll see exactly when and why it's dropping out of absorption. Mine was repeatedly restarting the charge cycle every time the alternator dipped, never completing absorption properly. Sorting the engine detection threshold helped enormously there.

@JimChapman74 — worth having a look at your absorption time settings in the VictronConnect app. By default the Orion can cut absorption quite short if it thinks the battery's nearly full. If your Fogstar Drift was sitting at a decent state of charge before the journey, it might be breezing through absorption in 20 minutes and dropping to float before you've even hit the M6. Try logging a session with Bluetooth connected and watch the actual input voltage over time — that'll tell you pretty quickly whether it's a genuine voltage issue or just the charge algorithm doing its job.