LED pucks getting hot

[Mark80]

Hi,

I recently purchased six 3W 12v LED undermount puck lights. I then purchased a 120vac to 12vdc 40W magnetic transformer/driver designed for LEDs.

I connected all the LED pucks in parallel and they work, but after about 30 minutes they are almost too hot to touch. I fear they are being over driven and will eventually burn out.

If I connect two puck in series, they run dimmer (not ideal), but don't ever seem to get hot. This leads me to think that individually they are getting too much current. I think the transformer voltage is stable - I get a reading that hovers around 13v. Is there something that I could add to fix this? I don't want to lose the brightness of the LEDs.

thanks!

 

[BobK]

Link to the "pucks" that you bought?

Bob

 

[Mark80]

LED pucks: https://www.amazon.com/LEDQuant-Dimmable-Under-Cabinet-Light/dp/B013RVNW80

Transformer: https://www.amazon.com/Watt-Dimmable-Magnetic-Transformer-Driver/dp/B00IBN6X22/

 

[Herschel Peeler]

Hi,

I recently purchased six 3W 12v LED undermount puck lights. I then purchased a 120vac to 12vdc 40W magnetic transformer/driver designed for LEDs.

I connected all the LED pucks in parallel and they work, but after about 30 minutes they are almost too hot to touch. I fear they are being over driven and will eventually burn out.

If I connect two puck in series, they run dimmer (not ideal), but don't ever seem to get hot. This leads me to think that individually they are getting too much current. I think the transformer voltage is stable - I get a reading that hovers around 13v. Is there something that I could add to fix this? I don't want to lose the brightness of the LEDs.

thanks!

The link for the lights doesn't indicate normal current at 12 V. Running at 13 V they could draw excessive current the result of higher current and higher voltage means lots more power. They are dimmable? A dimmer might be your answer.

 

[hevans1944]

You could also try placing one or two forward-biased diodes in series with the power pack output to drop the voltage presented to the puck lights.

 

[(*steve*)]

Yeah, sounds like neither the LEDs or the power supply are current line limited.

 

[Mark80]

Could this be a AC ripple issue?

 

[BobK]

Ripple should not be a problem, since the puck most likely just contains 3 LEDs in series plus a resistor.

The problem is too much voltage.

Bob

 

[(*steve*)]

Heh, I agree about the three LEDs in series, but there is no evidence of a resistor

(which is not to say there is not one)

 

[BobK]

If there is no resistor, then 12V is too high.

Mark, can you measure the current drawn when you supply 13V to the puck?

Bob

 

[Mark80]

The LEDS have built-in resistors.

I added a dc/dc buck and that seems to have solved the problem. The "LED transformer" was not putting out a constant 12V, so now it's more stable around 11ish V.