Orion Charge Rate Tapers to about 40% of Max

Anyone else's Orion-Tr Smart deciding it's had enough halfway through a charge cycle and just... giving up like a tired Labrador?

Mine's doing something similar on the boat — kicks off fine at full whack, then inexplicably tapers to around 40% of rated output and just sits there, smugly, whilst my Fogstar lithiums are nowhere near absorption.

Checked the obvious suspects:

• Input voltage from the alternator looks solid
• Temperature sensors aren't throwing any warnings
• BMS isn't pulling the plug early
• VictronConnect shows no faults, just politely throttling itself for apparently no reason

My suspicion is it's doing some sort of phantom thermal derating even though the unit itself isn't hot to the touch — it's mounted in a reasonably ventilated locker. Either that or there's some interaction with the MPPT on the same bus confusing the Orion's tiny brain.

Worth noting this seems to happen most when the alternator's been running a while, so I'm not ruling out the input voltage sagging just enough to trigger something internally — though I can't catch it in the act on the VRM.

Has anyone dug into this with Victron's support, or is there a known firmware gremlin lurking about? I've seen vague mentions of similar behaviour in other setups but nothing conclusive for a DC-DC scenario specifically.

Curious whether anyone's resolved it through settings tweaks or whether it's a case of just reflashing firmware and hoping for the best — would love to know if there's a pattern here before I start randomly poking things.

@Cerbo_Master seen this in my shepherd's hut setup. Orion was tapering off and I thought it was dying but turned out the input voltage was sagging more than I realised — starter battery wasn't holding well under load so the Orion was just protecting itself.

Worth checking:

• Input voltage under load (not just at rest)
• Temperature compensation kicking in oddly
• Whether your absorption voltage is set right for your battery chemistry

Mine was also doing weird things until I updated firmware via VictronConnect — there was a known bug a while back affecting the charge curve.

What's your battery? If it's LiFePO4 the tail current behaviour looks dramatic but can be totally normal depending on your BMS cutoff settings.

@Cerbo_Master had exactly this on my setup. Nine times out of ten it's the input voltage dropping under load — alternator can't hold it up and the Orion backs off to protect itself.

Worth checking your absorption voltage settings too. If it's set lower than what the BMS is expecting, it'll look like tapering but it's actually just… done, technically.

Also check your cable runs. Undersized wiring between alternator and Orion creates enough voltage drop to trigger the throttling. Went through this with my Fogstar lithiums last season — drove me mental before I found a dodgy crimp on the negative.

What's your battery chemistry? LiFePO4 profiles behave very differently to AGM on the Orion.

@Cerbo_Master worth checking your absorption voltage setpoint in VictronConnect — if it's set too low, the Orion thinks it's already "done" and backs off the current like it's clocked off at 4pm on a Friday.

Had this exact drama in my van — Fogstar LiFePO4 sitting at 60% whilst the Orion congratulated itself on a job well done. Bumped absorption from 13.8V to 14.2V and suddenly it remembered what it was built for.

@Cerbo_Master this one took me down a rabbit hole last winter. Mine was tapering identically — turned out the temperature compensation was the culprit. The Orion was reading an inflated battery temperature (sensor placement too close to the cells under load) and aggressively pulling back current thinking it was protecting against thermal runaway.

Worth checking where your temp sensor is physically sitting. Mine was cable-tied to the positive busbar, which runs warmer than the cells themselves.

Also — and this is specific to the Smart variant — check whether you've accidentally enabled adaptive charging via VictronConnect. That algorithm can behave oddly with LiFePO4 profiles that aren't properly dialled in, essentially second-guessing a battery that doesn't need babysitting.

Fixed mine by relocating the sensor to the cell face and disabling adaptive. Rock solid ever since.