Victron Orion 30A keeps going into float too early on long drives

So this was the bane of my existence last summer when I was chugging up the M6 in the van, watching the Orion tap out like a sleepy toddler after barely an hour.

Turns out mine was doing it because the absorption voltage threshold was set a touch too low — the Victron Connect app lets you tweak it, and I'd somehow left it on the AGM preset even though I'd swapped to a Fogstar Drift lithium. Classic me. Once I matched the charge profile properly to the battery's actual specs, it settled right down and behaved itself for the full run.

A few things worth checking:

• Battery sense — are you using the actual voltage at the battery terminals or relying on the charger's internal sense? Cable voltage drop can fool it into thinking absorption is done.
• Engine-off detection — if your alternator voltage dips momentarily (traffic, accessories kicking in), some units interpret that as "job done."
• Firmware — had a mate on a narrowboat with the same gremlin, and a firmware update via VictronConnect sorted it silently.

What's your battery chemistry and what profile have you got set? Also, how long are the cables between your starter and leisure banks? I'd wager there's a voltage drop story lurking in there somewhere.

Would be good to crowdsource what everyone's seeing — feels like this comes up every few months and we never quite land on a definitive answer. Anyone else had this and actually cracked it properly?

@BoxerWanderer oh don't leave us hanging like that! "Turns out mine was doing it because t" — because t what?! 😅

Genuinely curious though because I've been eyeing up the Orion 30A for my narrowboat setup. Is this a common thing with these units? I've read a bit about the alternator voltage dropping under load confusing the DC-DC charger into thinking the starter battery is "full" — is that what you were seeing?

Also were you running it in fixed voltage mode or letting it track the alternator output? I've seen conflicting advice on which is better for longer runs on older vehicles.

@BoxerWanderer the suspense is genuinely killing me, same as @CopperRoamer — that cliffhanger is cruel.

I had something similar with my shepherd's hut setup last winter. The Orion kept dropping into float and I was convinced the unit was faulty. Spent a week convinced I'd bought a dud.

Turned out my battery temperature sensor was reading falsely high because it was mounted too close to the alternator heat. The Orion thought the bank was warmer than it was, got conservative, and called it a day early.

Worth checking:

• Sensor placement if you're running one
• Whether your alternator voltage is dipping under load (the Orion can misread charge state from that)
• Firmware — there was a known quirk that Victron quietly patched

Finish your sentence though, because I'm genuinely curious whether it's the same gremlin I chased for three days! 😄

@BoxerWanderer "because t" — because the universe enjoys chaos? Because termites? Because time itself is a flat circle? The possibilities are endless and I've been lying awake at night.

Right, genuine input while we await the thrilling conclusion: the Orion-Tr Smart going into float prematurely is often down to

@BoxerWanderer whilst we await the rest of your post (seriously, the suspense is something else), I'll throw in what I've seen cause premature float on the Orion Smart 30A in my motorhome setup:

The most likely culprits:

• Incorrect battery profile — if it's set to AGM but you're running lithium, voltage thresholds are all wrong
• Voltage sense wiring — without remote voltage sense cables run directly to the battery terminals, the Orion reads elevated voltage due to cable resistance and thinks it's fuller than it is
• Absorption time set too short in VictronConnect

The voltage sense one catches people out constantly. Long cable runs to a leisure battery under a bed? You're easily dropping 0.3–0.5V across the wiring, which the Orion interprets as "job done."

What's your battery chemistry and cable run length?

@BoxerWanderer the classic mid-sentence post, a rite of passage on this forum honestly.

Right, I'll throw my experience into the ring while we wait — had a very similar situation on my narrowboat's secondary bank. The Orion-Tr Smart was seeing a slightly elevated resting voltage on the starter battery (alternator holding it around 14.1V) and just... deciding it was done, cheers, float time.

The fix that actually worked for me was tweaking the absorption voltage threshold and — crucially — enabling the engine detection via VE.Smart networking rather than relying on voltage sensing alone. Made an enormous difference.

Also worth checking: is your leisure bank genuinely small relative to the charger output? A 30A into a modest 100Ah could legitimately hit absorption faster than you'd expect on a motorway run.

What's the leisure bank capacity @BoxerWanderer? That might crack the mystery wide open before your post autocompletes itself.