Fixed 12v LED flood light - heat question (pics)

hi cpfers

i picked up this 6x LED work light from a local shop.
it is rated for 1.3amp at 12v, and i have measure this to be accurate with a meter.
it appears to be preforming as specified on the label.

BUT, after 30mins hooked up to a 12v lead battery the unit is hot to touch. enough to hold it for 10secs without pain. this i am ok with.
but after 1 hour, it is too hot to touch, this i am NOT ok with this. light output appears normal.

unfortunately the unit is glued and can not be disassembled without great effort.
but looking through the lens i can see that there is a driver on the board where the emitters are seated. i am not surprised since the unit says 10-30volts which suggests regulation.

my intention for this light was to be on a garage hooked into a 12v solar system.
but the heat issue gives me concern that it will not last long, or worse become a hazard.


my questions;
1. is this unit too hot or is this normal for this type of worklight? can it handle this heat for 6 hours daily?
2. because i can see a driver inside already, i assume this means i can not PWM regulate its supply without sending the built-in driver nuts
3. am i wiring this correctly by hooking to straight to 12v (considering its regulated internally)?

pre-thanks!

We've had some pretty hot weather here lately. Have your tests been run in high ambient temperatures?

It's not easy to tell from the picture but there seem to be a number of fins to help with heatsinking. Whether there is adequate surface area is the question. I certainly don't like the idea of an LED array that is too hot to touch.

If possible, can you try the same test on a cool evening with a little breeze running over the light to see if that makes a difference?

it was run at about 26C ambient without airflow, while she is in a metal finned housing it appears that it cant dissipate heat fast enough to regulate its temp.
the light was sold as a "work light", but im getting the feeling it is designed for a vehicle while in motion (for air flow)?

i will attempt to measure its surface temp.
ill also run it in front of a fan to see if the air flow is required to keep a reasonable regulated temp - thanks for the idea

Given that you are using a 12V supply, you could also fix a small computer fan to the heatsink. Pull one from an old case or power supply or just pick one up retail. You may need to bodgy it on with a bit of silastic or perhaps just start with a cable tie or two as a test.

If it worked, you'd just need to clean the dust and cobwebs out of it every month or so. Come winter, you may not even need that.

You can't post links in here but any chance of telling us a brand name or where you purchased it from?

Cheers

its to be mounted outside in the weather, so i cant use a fan. but good idea.
its a mechpro from repco. was on special but ive since seen them for half the price on ebay (AUS seller).

curious, if im seeing little coils on the board in this light, does the suggest that circuit is stepping up the voltage when required? could this unit run cooler at a higher voltage?

insane2k said:

its to be mounted outside in the weather, so i cant use a fan. but good idea.
its a mechpro from repco. was on special but ive since seen them for half the price on ebay (AUS seller).

curious, if im seeing little coils on the board in this light, does the suggest that circuit is stepping up the voltage when required? could this unit run cooler at a higher voltage?

Click to expand...

Odds are it will run about the same heat no matter the voltage. There will be some changes in driver efficiency over temperature, but most of the heat is still in the LEDs.

It would be best to measure the heat sink temperature. Hot to touch could mean 60C. That is hot, but not dangerously so. 6 hours per night = 2000 /year. If the unit last 20,000 hours that is 10 years. If you are using it for solar, odds are you have updated it long before that for better efficiency. Of course, with solar, you already paid more for the panel and way more for the batteries over time.

Not this brand, but I have PWMed a 12V work light with a built in driver. It's all in how they do their circuitry, where the capacitors sit in the circuit, etc. No guarantees it will or will not and what impact it will have. I managed to get a fairly linear relationship between PWM and dimming from about 20% to 100% using a 200Hz PWM.

Short term best bet is to look at temperature though and go from there.

Semiman

for anyone that has seen these flood lights around, this is whats on the inside.

this one that i was worried about the heat finally blew something and lost 3 lights.
epoxy has been poured over the board making it irreparable

lens is very difficult to remove due to the glue

usually the driver survives well with overtemp problems because of internal thermal protection [usually trips at 150C]. From the looks of it, the manufacturer didn't take advantage of that but instead isolated the driver PCB from the LED PCB. Glue was poured over for mechanical stability and is there to prevent inertia from shearing off the components in the event of jarring