Anyone else using a Victron Orion-Tr Smart to charge from their tow vehicle while running EV charging on site?

Running a Victron Orion-Tr Smart 12/12-30A between my Land Rover Defender and the shepherd's hut battery bank (3× Fogstar Drift 100Ah in parallel), and it's been genuinely brilliant for topping up on arrival before the solar kicks in properly.

The snag is I've started running a Type 2 EVSE off the same bank for slow-charging our Zoe overnight, and I'm wondering whether the Orion is even worth running whilst the inverter's pulling that kind of load — feels like I'm just shuffling electrons around inefficiently.

Has anyone actually measured whether the DC-DC input from the vehicle alternator makes a meaningful dent when you've got a 3.7kW AC draw overnight, or is it basically a rounding error and I should just crack on with the morning solar harvest?

Bonus points if you've got a narrowboat setup doing something similar — I'm half-convinced the answer is "bigger battery."

@AmyChapman89 snap setup — I've got the same Orion-Tr Smart feeding my hut's bank, though I'm running a pair of Fogstar Drift 200Ahs rather than three 100s.

The thing that caught me out early on was the engine detection threshold — mine kept firing up on ignition voltage alone before the alternator was properly spinning. Worth digging into the VictronConnect app and bumping that input voltage threshold up a touch if you're seeing any odd behaviour.

One genuine question though: you mentioned EV charging on site — are you pulling that from the same battery bank? Curious what your draw looks like because even a modest EV charger will flatten those Fogstars faster than you'd expect unless your solar harvest is keeping pace.

My hut taught me that lesson the hard way last February.

@AmyChapman89 interesting setup — I've been running something similar but on a narrowboat, Orion-Tr Smart feeding a 200Ah Fogstar bank while occasionally running a small EV charger off an inverter.

One thing worth flagging if you haven't already: keep an eye on the Defender's alternator temp when the Orion is pulling hard AND you've got EV charging loads on the site bank simultaneously. My setup was browning out the alternator on longer runs until I dialled the Orion back to 20A in the VictronConnect app.

Also worth enabling the engine detection via voltage threshold rather than relying on the ignition wire — more reliable in my experience with older vehicles.

What inverter are you running for the EV side? That's where my setup gets complicated — the draw profiles are pretty spiky.