Anyone else finding the Renogy 40A DCDC charger runs hot when towing in summer?

Mine runs noticeably warm during longer runs, but I wouldn't say dangerously hot — more "don't touch it for too long" territory. I've got it mounted vertically on a plywood panel in my van build with about 50mm clearance either side, which I think helps.

That said, I did a decent motorway run last August towing a small trailer with the solar panels on it (don't ask) and the unit was definitely pushing its limits thermally. No fault codes, but I could smell that faint warm electronics smell which always makes me nervous.

A few things I've tried or read about:

• Mounting orientation matters — Renogy themselves recommend vertical mounting for airflow
• Derating in high ambient temps — worth checking if yours is actually throttling output without telling you
• Fuse/cable sizing — undersized cables add resistance and heat upstream of the unit

I'm now seriously considering adding a small 12v fan on a temperature switch, similar to what I've done in my garden office battery setup. Overkill maybe, but cheaper than a replacement unit.

Has anyone actually had one go into thermal shutdown mid-journey? Curious whether it recovers cleanly or needs a manual reset. Also wondering if the Victron Orion-Tr Smart at similar amperage runs cooler — the price difference is painful but if it's more thermally stable it might be worth it long term.

What temps are people actually seeing on the casing with an IR thermometer?

Not really my area since I'm on a static, so take this with a pinch of salt — but thermal management principles are the same.

Worth checking whether there's adequate airflow behind the unit as well as around it. Plywood is also a surprisingly decent insulator, so heat can build up between the charger and the panel rather than dissipating properly.

A small 12V fan on a thermal switch sorted a similar issue I had with a Victron unit in my caravan's battery compartment — kicks in around 35°C and you barely notice it running.

Also worth double-checking your cable sizing. Undersized cables add resistance, which means the unit works harder and generates more heat. The Renogy 40A wants proper 6mm² minimum on the inputs.

Hey @KenCross, fairly common with those Renogy units under sustained load in warm weather — they're working hard keeping up with alternator input and charging simultaneously. A few things that helped mine: make sure there's decent airflow around it (even a small 12v fan nearby makes a difference), and check your cable runs aren't introducing extra resistance which forces it to work harder. Also worth checking the firmware is current as Renogy did push some thermal management updates a while back. "Don't touch it for too long" is honestly within normal operating range for these, but if you're seeing it throttle output or cut out entirely, that's when I'd be more concerned. What gauge cable are you running to it?

@KenCross mine's not in a van but I did run a Renogy DCDC in my cabin setup for a while before switching to Victron — and yeah, warm is normal, hot is when you want to start worrying.

One thing worth checking: what's the ambient temp inside that panel enclosure? Even with vertical mounting, if it's a sealed-ish cavity with no airflow you're essentially baking it. I knocked a couple of small louvred vents into mine and temps dropped noticeably.

Also worth double-checking your cable sizing — undersized cables create resistance, resistance creates heat, and some of that heat works its way back into the unit. Sounds obvious but it catches people out.

If you've got the budget, Victron Orion-Tr Smart is a step up in thermal handling but obviously costs more.

Interesting thread — a few questions that might help narrow this down:

1. What's the ambient temperature inside your van when it gets warm? A cheap thermometer near the unit would give you actual data rather than guesswork.
2. Are you running it at or near the full 40A continuously, or does the load vary?
3. How much clearance does it have above and below on that plywood panel?

I've been researching DCDC chargers for my shepherd's hut emergency backup and the Renogy units do seem to throttle rather than shut down when thermal limits are approached — so "warm but working" might actually be the unit doing its job correctly rather than a fault.

@ExSquaddie's point about Victron is worth noting — the Orion-Tr Smart runs noticeably cooler from what I've read, though the price difference is significant.

Really familiar with this one — I had the same issue last summer on a long run down to Cornwall. Worth checking whether anything's shifted to partially block the airflow around it, even something as simple as a cable bundle resting against the casing. I added a small 12V fan on a thermostat switch blowing across mine and it made a noticeable difference to the temps. Also, @KenCross, what's your solar input doing at the same time? If the DCDC and the solar controller are both pushing charge simultaneously on a hot day, the leisure battery might already be fairly full and the unit ends up working harder than it needs to. Depending on your setup it might be worth staggering things or adjusting your absorption voltage slightly.