Anyone else finding the Victron Orion-Tr Smart struggles to maintain 30A in warm weather?

Fitted a 30A Orion-Tr Smart isolated in my Transit a few weeks back, wired between the 12V starter battery and a 200Ah lithium leisure bank. Cable runs are short — about 600mm on the input side, 800mm to the distribution bar — and I've used 25mm² throughout, so I don't think it's a cable issue. In cooler weather it happily sits at 29–30A and the leisure battery tops up nicely on a decent motorway run.

The problem is that once ambient temps climb above about 22°C and the engine bay gets properly warm, I'm seeing it throttle back to somewhere around 18–22A. Victron Connect is showing the unit itself hitting 45–50°C before it backs off. I've got it mounted vertically on the bulkhead behind the passenger seat, clear of the engine bay, so ventilation should be reasonable enough.

I've seen a few people say mounting it externally on the chassis rail or adding a small 12V fan helps, but I wanted to check what others have actually tried before I start drilling more holes. Has anyone had success with a specific mounting position or a forced-air solution, or is this just an accepted limitation of the unit at 30A continuous?

Hey @MaxShaw, worth checking your input voltage under load — if the alternator's output is drooping at all when it gets warm, the Orion will back off its output to compensate. Also, have you set the input voltage threshold correctly in the VictronConnect app? Sometimes the default settings are a touch conservative.

The other thing I'd look at is ventilation around the unit itself. The Orion-Tr Smart will thermally derate if it can't shift heat effectively — in a Transit cab or bulkhead area things can get surprisingly toasty in summer. Even a small gap improving airflow around it can make a noticeable difference.

What's your actual input voltage reading when it's derating? That'll help narrow it down considerably.

Good timing on this thread — I had exactly this with my Orion-Tr Smart 30A on the narrowboat last summer during that proper hot spell we had.

Turned out the unit was throttling back due to thermal protection. Victron's spec sheet is quite honest about it if you dig in — output derates as internal temp climbs.

What fixed it for me was giving the unit some breathing room. I'd originally mounted it in a fairly enclosed panel void. Moved it somewhere with actual airflow and the difference was immediate — solid 29-30A all day even moored up in full sun.

@PartnerConvert makes a fair point about input voltage too, but I'd look at the mounting position first. These units generate real heat under sustained charge cycles and they will protect themselves before anything goes wrong.