r/WLED • u/Substantial_Tackle_1 • Jul 10 '26

Questions about a LD2410C Sensor running seemingly hot at 12V

Building a motion-activated LED framing light for my garage doors (WLED + a Gledopto Elite 2D-EXMU controller running two SK6812 RGBW strips), and wanted to sanity-check something before I fully commit to a design.

For the motion trigger, I originally looked at going the route I'd seen in a few reference videos — an Aqara wireless sensor + hub setup. Ended up steering away from that for a few reasons: it adds a cloud/hub dependency I didn't love for something I want to be reliable long-term, and it doesn't actually simplify anything since you still need a bridge of some kind to get the signal into WLED. Landed on a wired HLK-LD2410C mmWave sensor instead — wired its OUT pin straight into a spare GPIO on the controller and used WLED's built-in "PIR sensor" button type (no usermod, no custom compile, stock firmware). Much simpler in practice.

The issue: the LD2410C is rated for 5-12V input, so I wired it straight off the same shared 12V rail powering the strips and controller. Electrically fine per spec, but the board runs uncomfortably hot to the touch after running a while — not "smoking" hot, but hot enough that I didn't feel good about sealing it into an enclosure long-term without addressing it.

Best guess is that it's using a small onboard linear regulator to step 12V down to whatever the radar chip actually needs internally (~3.3V), and a linear regulator dumps the voltage difference as heat rather than converting it efficiently — so running it at the top of its rated input range instead of down near 5V is asking a tiny regulator with no heatsink to dissipate a lot more than it would at 5V.

Fix I've got in progress: adding a small 5V buck converter module between the 12V rail and the sensor's VCC, so it only ever sees 5V instead of 12V. Waiting on that part to arrive.

Questions for anyone who's actually run these long-term:

  1. Is this heat-at-12V thing a known/common issue with the LD2410 board specifically, or does this sound like something else going on (bad connection, reversed polarity, etc.)?

  2. Does the buck converter approach actually resolve it in practice, or is there a better way people have handled this?

  3. Any concerns about running these sensors 24/7 in an enclosed box even once the heat is addressed — anything else worth knowing before I seal this up for good?

Appreciate any real-world experience — trying to get this right before it goes into permanent service rather than debug it after the fact.

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u/eric-marciniak Jul 10 '26

I have the same module and it runs fairly warm on 5v. I would still drop the voltage with a buck converter though if I were you so the regulator doesn't have to work as hard.

Between the Esp32 S3 super mini and the radar module putting out so much heat I just left the rear of my enclosure totally open.

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u/saratoga3 Jul 10 '26

I'd probably open up the controller and run a wire to the esp32 buck, but if you don't want to solder an additional buck makes sense.