LED Bar - HardHat concept

[Chronos]

If it could be made waterproof there may be a use in caving and possibly climbing.

I know I'd LOVE to have that beam pattern and high CRI when hiking at night. Wow.:bow:

Don, any remote chance of you building a high CRI headlamp??? That beam pattern is perfect, the color rendition would help with my aging eyes issues in not being able to identify a 3D object when the LED washes it down to a 2D artifact. Minimize trips and help ID handholds in a more effective manner.

Maximum output wouldn't have to be the primary driver to a project like this. I see:
- Floody beam pattern
- High CRI
- A couple of useful light levels: a good low to preserve night vision (80+% of use) and a good high when needed (less than 20% of use)
- Some level of water resistance so it can be used in the rain and snow
- Perhaps the ability to run off of 2x123 (or maybe a 17670 or 18650) for longer runtimes

:tinfoil:

 

[KingSmono]

Very cool concept... I've always thought that a CamelBak system would make a good battery-host for something like this. If the person didn't want to wear a slim battery backpack, then you could use something like the "PackTeen" (pictured below) clipped or fastened somehow... and since you can clip the water-tube to your clothing, it'd be an easy way to run the wires. Just a thought!

 

[McGizmo]

I think the front end composed of LED's and optic is really easy and straight forward here. The challenge is in selecting a proper driver and battery source and then how to host these elements either together or remote from each other.

 

[AndyTiedye]

Any idea how much heatsinking it needs besides the aluminum(?) bar the LEDs are epoxied to?
Would that be enough if we ran them a bit below max current?

 

[adamlau]

Interesting. Not the hat, but the FLIR shots. We use one to evaluate the heat loss and gain of building envelopes. I will grab our FLIR for beamshots sessions the next time around .

 

[McGizmo]

Any idea how much heatsinking it needs besides the aluminum(?) bar the LEDs are epoxied to?
Would that be enough if we ran them a bit below max current?

Andy,
If you look at the results I posted, HERE, where there were 6 of the Nichias in the series string, I think you can get an idea of how much sink material is required. I wouldn't expect the light bar on its own to handle more than a single under driven LED let alone 4 of them. What I wish I had a better feel for is how mass of sink relates to surface area in terms of thermal relief.

 

[AndyTiedye]

If the current was stated for either of these, I must have overlooked it.

What current are you running through the hard-hat LED bar?

I assume that's a 350ma Xitanium in the other post with the 6 LEDs.

Are these LEDs more efficient at lower current levels?

A stand-alone light bar could also have slots cut in the back of it to improve heatsinking,
the way people often do with modded Maglites.

 

[McGizmo]

Andy,
On this LED bar here, high is ~330mA with med at 115 mA and low at 27 mA. In the example of 6 on a Xitanium, I measured 360 mA to the string on that particular driver (nominal 350 mA device). This lot of Nichia 083's does have a high Vf unfortunately and this means more heat and less photons than we are now used to with the current high power LED's.

Yes, you could cut fins in the LED bar which would increase surface area at the expense of mass reduction. Presumably this would have a net gain in thermal relief but to what extent and if there is some limit at which reduction of mass itself works against you, I don't know.

 

[mahoney]

Lots of mass in a heatsink only helps until it's hot, then it becomes a question of how fast heat leaves the heatsink which is a function of surface area, surface finish, and the heatsink shape. You do need sufficient material thickness to get heat conducted to the outer areas of the heatsink, so yes, past a certain point reducing mass will reduce the effectiveness of your heatsink. And for short and intermittent use, a heatsink with high mass and low surface area, or poor geometry, etc., could work OK assuming it would cool between uses.

Now that you have FLIR you can answer a lot of questions about what does and does not work, it looks like the hardhat is a pretty good heatsink. Maybe a bit of a bottleneck getting heat from the brim to the crown.

It is amazing what difference a finish can make too. I remember an exercise from college thermodynamics o-so-many years ago: Which gets hotter in the sun, a chrome plated steel plate or a black painted one? It turns out to be chrome, even though it reflects most of the light hitting it, it re-radiates very little of what it does absorb and ultimately will settle at a higher temperature than the black plate.

Back on topic, I suspect that increasing the contact area between the bottom of the LED bar and the hat brim, and/or putting a plate on the brim to help transfer more heat to the rest of the hat will result in more heat loss than fins on the top of the LED bar would.

 

[McGizmo]

Mahoney,
Thanks for the comments. Since I have been messing with the FLIR, I have been introduced to the concept of emissivity. If I don't calibrate the FLIR camera for the emissivity of the object being viewed, the measured temps will be off. I assume that the emissivity of a surface also has bearing on the object's ability to radiate heat.

 

[CM]

The whole rig weighs 2 lb & 2 ounces. The battery alone is 13 oz.

Is there room inside the hat for Li-Poly? I think these can be made thin and be shaped to fit. These are very light and putting it on top in the center would move the center of mass in a more ideal location. I like the streamlined design unlike the traditional hard hats with headlamp that looks like an afterthought. I think there's a market for these.

 

[McGizmo]

CM,
There is plenty of "head" room. I would guess a better solution would integrate a layer or region of Styrofoam integrated with any batteries or circuitry to cushion the crash zone of the area. The hat could be formed with the inclusion of a light bar in consideration as well.

I keep looking at a carbon fiber full face helmet I use with my Vespa and envision integrating a similar but less powerful light bar in it. Actually I would be happy with a single LED behind a sapphire lens driven by a three speed on CR123 cell on the motor cycle helmet. It could be faired into the cf shell and possibly use the cf as part of its thermal relief.

Every night, I use a baseball hat with a Mule mounted on the brim for "bug" collection out in the back yard. Many of the hats or at least visors have a plastic insert for the bill. I would think a stamped aluminum bill could be used and it would be the heat sink. Even if covered by fabric, it could provide sufficient relief and allow for a small light element.

 

[yaesumofo]

Re: LED Bar - Hardhat concept

I want one.
I wish I needed a hard hat on the job...
Don I find it hard to believe that Helmet companies would not be interested in a premium design for a light built into a motorcycle helmet. Like for map reading and also a couple of RED rear lights for Better visibility of the rider.
I would be Patenting these designs as quickly as I could draw them,.



Yaesumofo

CM,
There is plenty of "head" room. I would guess a better solution would integrate a layer or region of Styrofoam integrated with any batteries or circuitry to cushion the crash zone of the area. The hat could be formed with the inclusion of a light bar in consideration as well.

I keep looking at a carbon fiber full face helmet I use with my Vespa and envision integrating a similar but less powerful light bar in it. Actually I would be happy with a single LED behind a sapphire lens driven by a three speed on CR123 cell on the motor cycle helmet. It could be feared into the cf shell and possibly use the cf as part of its thermal relief.

Every night, I use a baseball hat with a Mule mounted on the brim for "bug" collection out in the back yard. Many of the hats or at least visors have a plastic insert for the bill. I would think a stamped aluminum bill could be used and it would be the heat sink. Even if covered by fabric, it could provide sufficient relief and allow for a small light element.

 

[JediNight]

I have a friend that works for the railroads doing tunnel repairs.
Showed him this thread and he is in love!

Can't wait to see if this becomes something for sale down the road:thumbsup:

 

[AndyTiedye]

Not sure if this is a "wait for the wave" thing or a "do it yourself" thing.
It looks like a casting, which would suggest there are more of these heads
somewhere. :candle:

If not, could you make one of these with a piece of aluminum bar and a grinder?

 

[McGizmo]

Hi guys,
This "proof of concept" has convinced me that there is some real meat here but the present battery and prototype converter are inappropriate in present form.

I think a reasonably clean battery pak smaller in mass can be designed to mount to the chin strap mount points on the side of the helmet (I think that is what those are) and likely a multi speed boost driver should be used as I assume the Vin would be less than Vf of the string. A pair of paks could be mounted port and starboard for better balance and greater capacity. Perhaps two 18650's in parallel (safety) could boost to 15V? :thinking: :shrug:

The light bar is a piece of 3/4" bar stock that I milled and turned. I bead blasted it to see if that would bring the emissivity of it in line with the hat itself for FLIR evaluation. Close but no cigar. The blasted finish may make it look like a cast part but it isn't.

The first step going forward with the idea is to get a MCPCB made that will host the 4 LED's and provide for clean mounting to the light bar.

Frankly, this is a rather ambitious undertaking that would be easier with more horsepower behind the project. I need to put more bench time and thought into it....

 

[Raoul_Duke]

I put on a hard hat everyday...and it would be great to have that much light whilst working...but I think it will be a long time if ever that these could be made for hazardous areas ( pottentially explosive atmospheres)

I like the concept. But the vast majority of the industry here use plastic hard hats, and are painfully slow in accepting change.

 

[McGizmo]

Raoul,
You speak with a voice of clear reality. I would imagine that the paperwork and qualifications involved could be quite daunting. I would imagine that any success in such hats would be in areas where need goes beyond status quo. I would also guess that an add on might be easier to qualify than something integrated and yet proper integration would provide a cleaner solution. In terms of going for intrinsically safe, this is doable from a design and manufacturing standpoint but the qualification process is not likely for the faint of heart.

EDIT: I have spent weeks crawling in attics with a headlamp on and the headlamp served me well but the lack of hair on the top of my head kept me from any knowledge of how close I was to roofing nails and scars on my head attest to this. If there is a next time which is likely, this metal hat will be worn. :green: I just hope I have come up with a better power pak by then.

 

[Art Vandelay]

Wow! That beam is perfect, the best I've seen. If you made these, would you consider selling the headlight separate from the hardhat? It is a great looking skull bucket, but I don't need a hardhat. Instead of attaching the light to a hardhat, I think it could be attached to a bicycle's handlebars, then the bike's aluminum frame could draw heat from the light, and carry the weight.

 

[CM]

Re: LED Bar - Hardhat concept

I want one.
I wish I needed a hard hat on the job...
Don I find it hard to believe that Helmet companies would not be interested in a premium design for a light built into a motorcycle helmet. Like for map reading and also a couple of RED rear lights for Better visibility of the rider.
I would be Patenting these designs as quickly as I could draw them,.



Yaesumofo

Lots of great ideas here. Motorcycle cops with flashing red/blue on the rear and white LED's for night time ticket writing :devil:

OK, I'm getting carried away but the patent thing is still valid.