super bight LED's casing gets very hot

Submitted: Sunday, Feb 07, 2010 at 08:08
ThreadID: 75833 Views:2335 Replies:2 FollowUps:1
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I bought a strip of 6 super bright LEDs a few months ago and just got around to wiring them to the 12 volt system in the caravan. They come in brushed metal housing about 300mm by 12mm by 4mm

Whilst trying to get their best siting for SWIMBO I left these LED lights on for about 5 minutes. Once determined I reached over to unplug the funny shaped 12 volt plug and I brushed against the housing with bare belly skin.

Very very hot. I had intended to fit the strip to the under shelves on the caravan with double sided tape but I am now worried about creating a possible fire risk. If I use nuts and bolts up through the shelf the heat may well scorch or burn the shelves.

Any similar concerns, solutions or experiences gratefully received.

Benny
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Reply By: olcoolone - Sunday, Feb 07, 2010 at 09:53

Sunday, Feb 07, 2010 at 09:53
White LED's will get very hot.

The temp the human body feels and what you think is hot is different to what is hot to another material.

Plastics for example have a melting point of starting around 120 Deg C plus., back to the human body your LED's may have a running temp of only 60 Deg C. but to touch with unexposed skin can cause burns.

If you touched something that was 60 Deg C. with unexposed skin for a few seconds your more then likely get 3rd degree burns.

Now getting back to the plastic as you can see the 60 Deg C. that can cause 3rd degree burns is not going to cause any damage to the plastic that has a 120 Deg C. melting point, as for fire the flash point of the plastic would have to be much higher then 120 Deg C.
AnswerID: 403060

Reply By: Gazal Champion - Sunday, Feb 07, 2010 at 13:00

Sunday, Feb 07, 2010 at 13:00
Hi Benny, Try mounting it on a length of aluminium extrusion like a 25 X 50 hollow section if space permits.
I have replaced a couple of those dicroic 12 volt halogen down lights which were set up in the van for bedside reading lights with 16 LED replacement lights, similar housing shape, and I have found that the LEDs get quite hot but not as hot as the dicroic halogens. I have dabbled over the years in electronics and have never known LEDs to get that hot, but then these recent super bright LEDs weren't around till a couple of years ago, I therefore find the heat they generate surprising.
Cheers, Bruce.
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AnswerID: 403093

Follow Up By: bennyzbit - Tuesday, Feb 09, 2010 at 20:39

Tuesday, Feb 09, 2010 at 20:39
Thanks for the advice. I decided to use a few washers between the houseing and the shelf. Except for the washers in 2 fixing places that gives me a 3mm air void between the rest of the housing and the shelf.


Thanks again

Benny
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