Anyone else running a Victron Orion-Tr Smart 12/12-30 alongside solar? Wondering how you're prioritising charge sources

So I've got a 200Ah lithium (a Fogstar Drift) in my van build and I'm running a Victron Orion-Tr Smart 12/12-30 off the alternator alongside a 200W panel going into an MPPT 75/15. Works brilliantly most of the time, but I've been scratching my head a bit about how the two charge sources interact when both are active at the same time — i.e. driving on a sunny day.

From what I can tell, the Orion and the MPPT just both push what they push, and the BMS on the Fogstar sorts out what it accepts. The battery doesn't seem to care, and I've not had any issues as such. But I'm getting some odd behaviour in VictronConnect where the MPPT occasionally shows absorption kicking in really briefly before dropping back to bulk, which makes me wonder if something's fighting itself.

Has anyone actually set up proper coordination between the two — like wiring the Orion's remote on/off to the MPPT's load output or something similar? Or is the general consensus just to let both crack on and not overthink it? Interested to hear how others have approached this, especially if you're also on a Fogstar or similar LiFePO4 without a proper DVCC setup via a Cerbo.

Hey @MarshPete, nice setup! One thing worth knowing with that combination is the Orion-Tr Smart will happily run alongside your MPPT without any real conflict - they're essentially independent charge sources and the Fogstar's BMS will sort out what it needs.

What I would suggest though is making sure your Orion is set to lithium profile with the correct absorption and float voltages to match your MPPT settings. Consistency between the two is key, otherwise you can get one source cutting out prematurely thinking the battery is full when it isn't quite there.

Also worth enabling the engine detection feature on the Orion if you haven't already - protects your starter battery nicely. What alternator are you running? Some of the older or smaller ones can get a bit unhappy with the Orion pulling 30A continuously.

@MarshPete one thing I'd add from running a very similar setup on my shepherd's hut build — the Orion-Tr Smart's engine detection threshold matters quite a bit here. Default is 13.2V but if your alternator is lazy on startup it can mis-trigger. Worth dropping into the VictronConnect app and tuning that threshold down slightly, or switching to the ignition-wire detection method if you've got a spare switched live available.

Also worth noting: the MPPT and Orion will effectively sum their charge currents into the Fogstar, so on a sunny day with the engine running you could theoretically be pushing 45A combined at absorption. Not a problem for the Drift's BMS, but worth monitoring with a battery monitor (BMV-712 ideally) so you're not flying blind on state of charge.

@MarshPete worth knowing that the Victron Connect app lets you set a tailored absorption/float profile on the Orion-Tr Smart to exactly match what your MPPT 75/15 is doing — so both sources are singing from the same hymn sheet rather than one undoing the other's hard work.

I ran a Fogstar Drift in my shepherd's hut for about eight months before I realised my Orion was finishing at 14.4V whilst my MPPT had been carefully floating at 13.8V. The battery didn't complain, but it's the sort of thing that'll quietly reduce cycle life over time, and I'm pathologically incapable of ignoring that sort of thing.

Get both profiles matched to Fogstar's published spec — they actually publish it properly, which not every manufacturer bothers to do — and you're sorted.