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

Mine did exactly the same until I realised the default absorption voltage was set about 0.3V too low for my Fogstar Drift cells — bumped it up and suddenly it actually uses the full bulk phase like it's supposed to.

Worth checking a few things:

• Tail current — if yours is set too sensitive, it'll bail into absorption the moment your leisure battery gets a decent surface charge going
• Battery temp — if the Orion thinks it's warmer than it is (dodgy sensor or no sensor fitted), it'll derate and rush through bulk
• Cable voltage drop — seen this catch people out loads of times on here, Victron Connect shows input voltage not actual battery voltage, so if your cables are marginal you're losing more than you think

The "long drives" bit is interesting though — are you saying it starts fine but flips early, or goes straight into absorption from a cold start? Because those are two different problems and I've had both on my setup over the years (still not entirely convinced the Orion 30A firmware is fully cooked if I'm honest).

Chuck your settings in VictronConnect and screenshot the charge graph — someone on here will spot it in about 30 seconds flat.

Anyone else running the 30A on a lithium build noticed the same? Feels like this comes up every few months and we never quite nail down one root cause.

@Brummie84 worth also checking your cable run from the starter battery — voltage drop across undersized wire will fool the Orion into thinking absorption threshold is reached earlier than it actually is. Had this exact issue on my narrowboat, turned out the 4mm² cable I'd run was nowhere near adequate for 30A over that distance. Jumped to 10mm² and the bulk phase extended significantly.

What's the cable length and cross-section on yours? The Victron calc tool is handy for working out minimum sizing — generally want to keep total voltage drop under 0.5V across the run.

Great catch @Brummie84 — the Fogstar Drift cells do seem to want absorption closer to 28.4V (4S) rather than Victron's conservative default.

One thing worth adding: if your alternator is smart/variable-voltage (most post-2015 Euro 6 engines), the Orion's input voltage can drop significantly under load, which compounds the issue @Spud79 raised. Mine would regularly see 13.1V input mid-motorway despite a healthy alternator — the Orion interprets that drop and backs off bulk current prematurely.

Fix that worked on my Vivaro setup:

• Enable engine running detection threshold (raise it slightly)
• Set a longer absorption timer rather than relying purely on voltage trigger
• Check the Orion's own voltage sensing isn't reading from a poor point in the circuit

The VictronConnect history tab is brilliant for diagnosing this — you can see exactly where bulk terminated and correlate it with your drive times.

@VivaroWanderer 28.4V is fine but be precise about why — that figure is at 25°C. If you're running the Orion without temperature compensation and your battery is cold (sat in a van overnight in January), you should actually be pushing closer to 28.8V for proper absorption. Victron's temperature coefficient for LiFePO4 is effectively zero by default because most BMS units handle it internally, but the Fogstar Drift BMS isn't communicating with your Orion unless you've wired the VE.Direct port properly.

Also worth checking: the Orion's absorption time setting, not just voltage. Short drives mean it never completes absorption regardless of voltage threshold. Bump the timer up if you're doing mostly urban stop-start runs.

@Spud79 makes a valid point too — measure actual voltage at the Orion input terminals under load, not at the battery posts.

@WhatsAFuse65 has the right end of the stick — temp compensation on the Orion-Tr Smart is -16mV/°C for a 24V system, so on a cold January motorway slog your target voltage should be creeping up noticeably above that 28.4V baseline, not sitting static like a lemon. Set it wrong and you're basically never fully charging. My van setup with Fogstar cells taught me to connect the Orion to the VictronConnect network and let the BMV-712's temp sensor do the heavy lifting via DVCC — single source of truth, no arguing between devices. Without that, you're just guessing at voltage figures and wondering why your SOC never hits 100%.

@Rob1963 that's useful context on the mV/°C figure — does the Orion-Tr Smart actually apply that compensation automatically if you enable it in VictronConnect, or do you still need to manually adjust the absorption setpoint?

Reason I ask is my setup is in a garden office rather than a vehicle, so I've got a bit more control over ambient temps, but I'm curious whether pairing it with a BMV-712 (which has the temp sensor) actually feeds data back to the Orion or if they're just separate systems talking past each other. The VE.Smart networking side of it always confuses me slightly.