Anyone else finding the Renogy 40A DCDC charger runs hot on long motorway drives?

Had this exact issue last summer doing a long run down to the Eurotunnel — probably four hours solid on the motorway with the engine thumping away and the Renogy working flat out the whole time.

Mine was tucked into a poorly ventilated locker and I could smell that warm electronics smell which, frankly, sets alarm bells ringing. Pulled over at a services and it had throttled itself back — thermal protection doing its job, but still not ideal when you're trying to bulk charge your leisure bank on the move.

Few things that made a real difference for me:

• Relocated it to a spot with actual airflow rather than a sealed cubbyhole
• Added a small 12v fan (triggered off the same circuit) blowing across the heatsink
• Checked my cable runs — undersized cables add resistance and heat upstream

Worth noting these units will derate in high temps, so if you're seeing lower charge currents than expected on hot days, that's likely why rather than a fault.

Curious whether anyone's swapped over to a Victron Orion-Tr Smart instead and found it runs cooler in practice — I've seen them mounted in tighter spots on some builds without issue, but could just be lower ambient temps in those installs.

Anyone else had similar bother, particularly on European trips where you're covering serious distance in one go?

@Macca not a motorhome bloke myself — I'm more static caravan and cabin — but I ran a Renogy DCDC on my Land Rover for a while before going full off-grid and yeah, they do run warm under sustained load.

Worth checking a few things:

• Mounting orientation — Renogy spec vertical mounting for airflow, a lot of people ignore this
• Ambient temp — engine bay heat soak makes it significantly worse
• Cable runs — undersized cables create resistance which adds to the thermal load

Mine throttled back rather than cooked itself, which is the safe outcome I suppose. Eventually swapped to a Victron Orion-Tr Smart and the difference in build quality is noticeable — runs cooler and you get proper monitoring via the app.

Might just be worth the upgrade if you're doing regular long hauls.

@Macca four hours solid is absolutely prime thermal throttling territory with those units. The Renogy 40A runs a pretty aggressive charging profile and the internal temps climb fast when ambient is already elevated from engine bay heat soak. Worth checking whether yours is mounted vertically — the fins are designed to convect upward, and I've seen people mount them horizontally and wonder why they're cooking.

On my motorhome setup I added a small 12V fan triggered off the charger's "charging" output line. Dropped operating temps noticeably on long runs. Crude but effective.

Also worth logging your actual output current — if it's hitting that 40A consistently for four hours, the unit is arguably working exactly as designed. The question is whether your mounting location is giving it any fighting chance thermally. Where have you got yours positioned relative to the cab?

@Macca worth checking where you've actually mounted it — I made the mistake of tucking mine too close to the engine bay bulkhead in an old Defender setup and the ambient temp absolutely cooked it. Even a few inches of clearance makes a difference.

Also, have you checked whether it's actually throttling or just feeling hot? Those units can run alarmingly warm and still be within spec. Grab a cheap IR thermometer and check the heatsink properly.

If it is throttling, Victron's Orion-Tr Smart handles sustained high-current runs better in my experience — pricier but doesn't grumble on long motorway stints. Might be worth the upgrade if you're doing regular Eurotunnel runs.

Mine hits temperatures that'd make a Greggs pasty jealous on the M6 — slapped a 12v computer fan on it wired to a thermal switch and now it runs like it's on a spa day.