My 3 day old RiverRock Luxeon K2 3AA headlamp is ruined :(

This is the new RiverRock K2 headlamp, sold exclusively at Target.

This incident really says Mag really know what they're doing. Thermal management is a must in ANY LED flashlight. Even for an aluminum flashlight, what do you suppose would happen if it got left on inside an insulator? (you put it in your sweatpants while it's on, take 'em off and forget about it and the light continues to run in the pocket)

When you drive a K2 Luxeon at 3+ watt (0.7A with freshly charged NiMH) with a heatsink about the size of the head of a house key and enclosed in a plastic, it will about 140C and melt down... What a surprise.

I think the designer depended on usage of alkaline and the light would not operate at maximum output for long time before the voltage drops and power consumption is dramatically reduced.

How else are they going to claim a long runtime otherwise?

I let it run for about two hours on a set of 1800mAh AA NiMH batteries before I noticed the case was deformed. When I tried to tilt the head, it came off. It got so hot that it deformed and ripped itself off from the screws.

I measured the heatsink temperature and it was 139C or 282F. I'm surprise it still works at all.

Meltdown!


3W+ power through K2, this heatsink


Yeah, it got hot. Are you surprised?


Yes I am surprised. How does it still work?

Re: My 3 day old Luxeon K2 3AA headlamp is ruined

Handlobraesing said:

This incident really says Mag really know what they're doing. Thermal management is a must in ANY LED flashlight. Even for an aluminum flashlight, what do you suppose would happen if it got left on inside an insulator? (you put it in your sweatpants while it's on, take 'em off and forget about it and the light continues to run in the pocket)

When you drive a K2 Luxeon at 3+ watt (0.7A with freshly charged NiMH) with a heatsink about the size of the head of a house key and enclosed in a plastic, it will about 140C and melt down... What a surprise.

I think the designer depended on usage of alkaline and the light would not operate at maximum output for long time before the voltage drops and power consumption is dramatically reduced.

How else are they going to claim a long runtime otherwise?

I let it run for about two hours on a set of 1800mAh AA NiMH batteries before I noticed the case was deformed. When I tried to tilt the head, it came off. It got so hot that it deformed and ripped itself off from the screws.

I measured the heatsink temperature and it was 139C or 282F. I'm surprise it still works at all.

Meltdown!

3W+ power through K2, this heatsink

Yeah, it got hot. Are you surprised?

Yes I am surprised. How does it still work?

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Wow! Thats a shame,Good thing it wasnt on your head

Is it hot in here, or is it just the melting headlamp I'm wearing?

Sorry about the headlamp though. I can see this as becoming a more common concern as higher powered, hotter running LED lamps become vulnerable to damage from poor cooling. A small piece of metal for a heatsink encased in a large plastic enclosure is not a sufficient way of cooling a high output LED obviously. They should have made the whole front casing/bezel out of aluminum at least, that would make a big difference.

I would have no hesitation returning that as 'not fit for purpose'.

w

Maybe they should have used a cooler running Seoul P4!

Handlobraesing said:

This incident really says Mag really know what they're doing.

Click to expand...

Yep, Mag says don't use rechargables with their poorly sinked lights.

Joel

that is what i dont understand, why have a plastic case around a headlamp, when a Lightweight aluminum one would weigh just as much, and serve the fuction of heat sink?
if these guys are selling to backpackers, mabey they have heard of titanium by now while its not the greatest heat sink metal in the world, its gotta beat plastic by a bit.

wakibaki said:

I would have no hesitation returning that as 'not fit for purpose'.

w

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Shave your eyebrows and bangs, or wear a ballcap with charcoal smeared on the front. No one would argue about an overheating headlamp then :lolsign:

That sucks. Hey, maybe everyone should quote hando's post!!

That's one of the big advantages of buying from a large chain. They will exchange or refund with no problem.

lhivernant said:

Yep, Mag says don't use rechargables with their poorly sinked lights.

Joel

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That might be the only thing RR can change about this light. If I understand the OP correctly, the light melted while in a pocket. If it had better thermal transmission the heat would've transferred to the fabric of the pocket rather than contained in the plastic housing and that can result in worst injury since the thing was way above boiling point.

Ideally, some sort of thermal shut off would be good IMHO. But maybe that would add too much to the cost, as would an alumininum or ti housing. Something should be done though, even if only for liablilty reasons.

Your observations about design deficiency reaffirms my fear of using a resistor to drag down the current for LED lights: Small changes in voltage make huge swings in current!

Is that heatsink even Aluminum? It almost looks like cheap metal or tin. Return it for sure - just don't tell'em you put NiMh in there. They won't loose anything and will send it back to the manufacturer who then may rethink how they built these if they get enough coming back.

mmmflashlights said:

Is it hot in here, or is it just the melting headlamp I'm wearing?

I can see this as becoming a more common concern as higher powered, hotter running LED lamps become vulnerable to damage from poor cooling.

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yeah that looks like galvanized steel to me, not aluminum.

it looks like with modern leds, the led, driver, battery, and heatsink are really the important issues. But there hasnt been much discussion on heatsinking, maybe CPF could add a section for discussions about thermal management, a place to discuss heatsinking materials and techniques, where to buy materials, etc. For anyone building from scratch this would be super helpful.

matrixshaman said:

Is that heatsink even Aluminum? It almost looks like cheap metal or tin. Return it for sure - just don't tell'em you put NiMh in there. They won't loose anything and will send it back to the manufacturer who then may rethink how they built these if they get enough coming back.

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It seems like it is, although it's largely irelevant as aluminum wouldn't help one bit in limits imposed by enclosure.

I'm thinking about taking mine back after seeing this. :sweat: Do you think I'd be ok running it at a the lower levels with alkalines?

Patriot36 said:

I'm thinking about taking mine back after seeing this. :sweat: Do you think I'd be ok running it at a the lower levels with alkalines?

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Yeah, but the LED itself is controlled by PWM, so it flickers like nuts and tend to make fast moving parts appear to be turning very slow backward or stopped depending on the speed of rotation.

The light starts on high, then each click progress through high, medium, low, flash then off. If you push the button after giving it a second or two, it becomes a power off button rather than cycle through all the mode. The mode is not retained. Next time you turn it on, it starts on high.

I'll insulate the beast and see if I could get it higher than 140C

In contrast...

I did a runtime on a Seoul-modded 3AAA HASTO headlamp. It also has a plastic body covering a metal plate heat sink. The body barely got warm at all on 3W, and the light did not diminish any more than usual during the first few minutes (a sign of poor heat transfer from the emitter)

So your HASTO on the 3W setting is actually running at a pretty steady 1W?

TorchBoy said:

So your HASTO on the 3W setting is actually running at a pretty steady 1W?

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Probably.