6 LED Lantern

havand

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I really like to go camping and love LED lights. Problem looking for a solution? All the available lanterns I've seen are what I would call a poor implementation of a lantern. Sure, they're cheap, but that's just the problem....They're cheap. The light output is paltry when used for area lighting. I wanted it to survive a fall. I checked out all the lanterns at the usual places and did some searching on the forums. I found that except for custom made lanterns, no one was offering anything I was interested in. My solution? Make my own, better lantern that would allow me free lumens without the need for a constant gas source or the need to deal with messy fuel.




I sat down and thought out what I wanted in a lantern. Long runtime is very important, but I also wanted the ability to turn the light up high for short periods. I wanted something fully variable, not just with levels. I chose a Shark driver and paired it with 6 SSC stars. Overkill? Maybe, but I wanted good efficiency at lower drive currents (more LEDs, so less current for better lm/w) and wanted to be able to really crank it when needed. I paired the shark and 6 LEDs to a 9 cell 11.1V, 6600mAh li-ion pack. I wanted the ability to dim the lantern all the way down, keeping in mind the VF drop at low currents I chose a lower voltage pack.

The construction was important to me. I wanted the lantern to be near indestructible. I researched the available options and picked out a 1/4" walled acrylic tube that is weather resistant. I lightly frosted the inside of the tube to help disperse the light and to avoid glare to the eyes. I picked up 2, 1/4" thick 6061 aluminum pieces for endplates. I took 1/4" stainless steel threaded rods and used them to compress the tube between the endplates on each corner. The lantern can survive a good fall or impact without breaking a sweat.

lantern9807001bs5.jpg


I incorporated a 12V charger into the design to recharge the lantern anywhere. The PCB protection, I chose had the ability to use a battery level indicator with 5 red indicator LEDs. Each represents 20%, and below 20%, it flashes. A quick press of the button lights them up for 10 seconds. The PCB protects each cell pack (3 18650 cells in parallel) from overcharging, overdischarging and overdraw by the driver.

By using a 6 LED pattern, equally spaced, the light dispersion is nice and insures there are no large gaps between the LED hotspots. I was afraid that by using 3 or 4 LEDs I would have centralized hotspots in various places with obvious gaps in lighting. I was trying to avoid major artifacts that plague most cheap lanterns that can be bought by various companies. After seeing the newest Colman lanterns, I'm sure you all know what I mean.

lantern9807002zo2.jpg



lantern9807004ri9.jpg


On low, the lantern draws about 7.5mA from the battery. On high, about 1.25A. Except for the corner support rods, the dispersion pattern is very nice. I've drawn up some ideas on how to get rid of the square endplates to let more light shine up and down from LEDs.

lantern9807007pk5.jpg


It is very difficult to show exactly how bright the lantern is, but the table in the background in the following picture is perhaps 10-15 feet from the lantern.

009zd9.jpg



In this picture, the light shining to the left of the lantern is a Dereelight SSC on high with tight focus.

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I find this lantern much more effective than the cheap 1 LED ones that can be found at most stores or online shops. They typically have a poor beam pattern with pitiful output for serious use or poor runtimes. My lantern will make a great area lighting tool for my fall camping trips. It has enough power to truly light up a large area with usable light. In addition, by using a Li-ion battery pack, the battery is ready to go in all reasonable weather conditions that would kill the output from NIMH cells.

Honestly, I was quite shocked at the lack of quality offerings in this particular market, which led me to go ahead and make my own solution. It performs its task well and has met all my expectations for get togethers and nighttime fire sessions. I tend to use it at lower drive currents for the efficiency and runtime. Frankly, it is too bright on high to be used as 'subtle' lighting when hanging out with friends. The ability to dial in the drive level you want is a big plus. I've run it in excess of 1/2 hour on high without trouble from the shark driver. Keeping the Shark cool is a big challenge.

I've also integrated a connector that allows you to connect the lantern to a 12v source, such as a car battery, and completely bypass the battery system for extended runtime sessions from your car battery or other available source. A great feature for versatility.

I have ideas for improvements, I'd like to implement on the next build. I'd be interested in hearing any suggestions for improvement you guys may have. If interest warrants, I would be willing to do a small run of lanterns.
 

Bushman5

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thats really neat! got any pics of how it lights up the dark forest?

:twothumbs
 

jeffosborne

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Great job, havand!You have definately been thinking outside the box to get this light made.Does your battery protection circuit detect temperature too? Seems like your batteries might be subject to some heat on the high-setting, enclosed as they are in the plexi.A question: you mention using a shark driver, are there two drivers? I am guessing that your 6 LED's are wired in two series string of 3 LED's each. Is that right?Also I like seeing your low at 7.5ma - it is suprising what a little juice will do with a modern, efficient LED. I use Luxeon Rebels in my home as night lamps, and they run at 50ma and 100ma, plenty for stairways and bathrooms.Thanks for sharing your post and the photographs!Jeff O.
 

havand

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Great job, havand!You have definately been thinking outside the box to get this light made.Does your battery protection circuit detect temperature too? Seems like your batteries might be subject to some heat on the high-setting, enclosed as they are in the plexi.A question: you mention using a shark driver, are there two drivers? I am guessing that your 6 LED's are wired in two series string of 3 LED's each. Is that right?Also I like seeing your low at 7.5ma - it is suprising what a little juice will do with a modern, efficient LED. I use Luxeon Rebels in my home as night lamps, and they run at 50ma and 100ma, plenty for stairways and bathrooms.Thanks for sharing your post and the photographs!Jeff O.


Jeff,

The battery protection circuit does NOT detect temperature, but I'm not too concerned about this. the LEDs are heatsinked to the top plate and the batteries are (except for a layer of insulator) very close to the bottom plate. The tube does not seem to get very warm, but the top plate gets quite toasty. I need to come up with some extra heatsinking to help remove that heat!

All 6 LEDs are in series. I got USxxH SSC LEDs for this project, which have a VF of 3-3.25 @ 350ma. I might not be getting the full 1 amp out of the shark because near the top end, the VF of all the emitters may have reached shark's limit of 22volts output. To be honest, this isn't an issue. That last little bit of power isn't going to produce tangible results and will suck down the battery. I've even been considering limiting the potentiometer to 15k instead of 20k to cutoff the very top end drive currents to save battery life. While using it, I most often set it @ 350ma - 500ma drive current. Nice mixture of light and battery life. 7.5ma is actually enough to see in the middle of the night, in a tent, to put on your shoes or whatnot.

::: Greg

EDIT: I can't really use 2 shark drivers with strings of 3 LEDs, because the shark driver needs to be in boost at all times. The battery input needs to be lower than the output voltage. I would need to change the battery configuration to do this. Currently, it is an 11.1v pack. I would probably have to lower the battery pack voltage to 7.4v and go to an 8 or 10 battery config. Do-able, though.
 
Last edited:

clg0159

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Nice! I have also wondered about the lack of quality lanterns. I recently went backpacking through Rocky Mountain National Park and took only torches because of the lack of a durable, high output lantern. This is a VERY interesting solution:thumbsup:
Although it is too heavy I'm sure for backpacking, a little tweaking of this design could yield the perfect lantern for carrying. Thanks for sharing!
 

havand

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Nice! I have also wondered about the lack of quality lanterns. I recently went backpacking through Rocky Mountain National Park and took only torches because of the lack of a durable, high output lantern. This is a VERY interesting solution:thumbsup:
Although it is too heavy I'm sure for backpacking, a little tweaking of this design could yield the perfect lantern for carrying. Thanks for sharing!

What would be acceptable for backpacking? a 2 LED tent light?
 

cnjl3

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I like it. But since the acrylic is so thick - wouldnt it be possible to keep the end caps in a slightly larger circular shape and run one bolt down the center with a wing nut on top? That would reduce your hardware and eliminate all the shadows from all the bolts you use:)
 

havand

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I like it. But since the acrylic is so thick - wouldnt it be possible to keep the end caps in a slightly larger circular shape and run one bolt down the center with a wing nut on top? That would reduce your hardware and eliminate all the shadows from all the bolts you use:)

Yes, very much so. I put together this model, but i'm not sure of the cost of machining yet (or about it's ability to dissipate enough heat at max drive for long periods). That was the general idea, a center rod, holding the 2 sides on in tension with notched endplates that fit into the acrylic.

lantern1kc3.jpg




jch79: Appreciated :) I'm trying!
 

havand

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Maybe the bottom cap can be like your above picture but the top could be just plain sort of like this?


I understand what you're saying. However, if I use the same endcap on the top and bottom, it reduces (potential) production costs significantly, as well as gives you two perfect places to hang the lantern from or put a strap clear through from one side to the next. You could carry it with this configuration, etc.

I'm not shooting down your suggestion, please don't see my response as that. I'm merely explaining why I put the design down the way I did. Keep'em comin!:twothumbs
 

havand

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Did a runtime test today. On high, there is simply too much heat to dissipate without excessive/active heatsinking. I'm toying with the idea of limiting the output via a 10k potentiometer instead of the 20k currently used. This visibly does reduce the light output a little, but cuts the draw on the battery nearly in half! I set the potentiometer to 10k this morning and turned it on at about 9:45 am. I don't have the setup to test the battery voltage while in use, but testing it just after being turned off. The battery voltage is probably sagging a little under load, but i'm not pulling much current (relatively) from the 6.6A battery with a draw of ~0.7A.

9:45AM: Battery Voltage ~ 12.4V Current to driver: 0.67A.

3:45PM: Battery voltage ~ 11.14V Current to driver: 0.7A.

6:15PM: Battery voltage ~ 10.87V Current to driver: 0.72A.

7:45PM: I went to check on the light and it had shutoff. The heatsink was
still mildly warm. It probably shutoff between 15-30 minutes
earlier, around 7:15-7:30PM.


This puts the runtime at about 9.5-9.75 hours. I had calculated it to be about 9.4 hrs, so i'm pleased.

Calculations:

12.4V *0.67A= 8.3W. Figure the battery sagged to, maybe 11.5V?

Gives 11.5V*0.67A= 7.7W

Figure the driver is operating at ~85-90% efficiency.
7.7W*0.85= 6.55W
6.55W / 6 LED= ~ 1.1W per LED.

Pick middle of the bin, so 3.125V @ nominal.

1.1W/3.125V = ~ 0.35A

This puts them at nominal voltage and current. By the bin labeling, each LED should be 91-118 lumens. Again, figure middle of the bin, 104.5 lumens per LED.

104.5lm/LED * 6 LED= 627 lumens.


So, if I decide to replace the potentiometer with a 10k unit, the lantern would be capable of 627 lumens for ~ 9.5 hours.

I could leave the 20k potentiometer for brighter capability, but i'm worried about the LED health over time from the high temperatures should someone forget to turn the lantern down after about 0.5-0.45 hours. After about an hour, the endplate of the lantern, on high, measured 115-120 F.
 

havand

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John,

This project got put on the back burner for a bit. As we had discussed previously, I have refocused my efforts on a smaller, more compact version. That is not to say this one will not be built. However because of the (significantly) higher costs involved, it will probably be produced 2nd. I'm still drafting up the newer version and trying to sort out the mess of circuitry I will need. As long as I don't hit any major snags, a variant of this SHOULD see the light of day in the future.

::: Greg
 

kurni

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Hi Havand,

I got this idea when reading this thread. Considering the thickness of acrylic, would it be possible to thread 1 end & replace M@g bezel. We just need a shiny cone (an inverted reflector) at the other end to make it a lantern. I suppose the thickness of the acrylic will hold the reflector and or the lens that is required to hold cluster M@g.

It will be awesome to be able to unscrew an aspheric M@g beazel & replace it with a portable acrylic tube to convert a laser to a lantern.

I'm very interested in such versatile add-on.
 

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