Blue smart charger 12v 15a: Is 72 degrees C too high an operating temperature in Bulk cycle?

Been meaning to raise this one for a while, actually.

Running my Victron Blue Smart IP65 15A in the van last summer during a long bulk cycle — we're talking a fairly depleted 200Ah LiFePO4 bank from Fogstar — and I clocked the unit getting seriously warm to the touch. Stuck my infrared thermometer on it out of curiosity and got readings nudging 68–72°C on the casing.

Now, Victron's documentation is a bit vague on what's "normal" versus "concerning" at that charge rate. The unit didn't throw any errors, no thermal shutdown, just cracked on. But I was parked up in direct afternoon sun on the South Downs, so ambient wasn't exactly helping matters.

What I did notice is that once I repositioned it — got it out of the sun and gave it a bit of breathing room away from the wheel arch — temperatures dropped noticeably, maybe 10–12°C, without any change to the charge profile.

So is 72°C a genuine red flag, or is it just physics doing its thing when you're pushing 15A continuously? My gut says the mounting position and ventilation matter enormously with these units, and a lot of people underestimate that when fitting them into tight van builds.

I've never had a failure on mine, but I'm also fairly cautious about not running bulk cycles in enclosed spaces during hot weather now.

Curious whether anyone else has proper data on this — ideally from a cooler environment where ambient isn't a variable. Has anyone actually triggered thermal protection on one of these, and at what surface temp did that happen?

@SussexVanLifer 72°C does sound on the high side to me. What's the ambient temp inside the van when this is happening? Mine gets toasty in the static caravan but I've never seen temps that extreme on the Victron.

Few questions:

• Is the charger mounted flat against a surface or does it have airflow around it?
• Is the 15A limit actually being hit sustained throughout bulk?
• Have you checked whether the unit is throttling back current when it hits that temp?

I ask because I've noticed my Blue Smart will derate itself before doing anything drastic — so the real question is whether it's alarming at 72°C or just running warm and carrying on fine.

What does the VictronConnect app show for actual output current at that point?

@SussexVanLifer had almost the exact same situation in my motorhome two summers back — parked up in the Cairngorms of all places, not exactly the Sahara, and my Blue Smart was hitting similar temps during a heavy bulk cycle.

Turned out the charger was wedged against a cabinet wall with barely any airflow around it. Moved it to an open bracket, ran a small 12V fan nearby, and it dropped a good 15°C instantly.

These units throttle themselves before anything catastrophic happens, but sustained high temps do shorten the life of the internals over time — Victron will tell you the same if you ring their UK support line.

Check your mounting position first. Airflow is everything with these. If it's already well-ventilated and still hitting 72°C, I'd be looking at whether your cable sizing is contributing heat at the connection points.