Micro Lantern build

datiLED

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Everyone has that family member that has zero reservations about asking you to do something that is a huge undertaking. For me, it is an aunt on my mom's side that shall remain nameless. Last March, at the start of the pandemic, she asked me to build a few lanterns for a friend of hers that lives off-grid in Hawaii. I suggested that she get a few commercial lanterns off of Amazon, but that was quickly shot down. What about my AA battery drainers? "Not bright enough... You work with electronics and LEDs. It should be easy for you." So after 14 months of PCB designs, prototypes, failed 3D prints and current adjustments, I present the datiLANTERN. It was originally going to use a 3D printed body that could house a 18650 or 3x AA cells in series. That was quickly set aside in favor of something easier, and that I am familiar with. (I am still learning about my 3D printer, and have not got it dialed in yet.) The magnetic connection, which has been improved with the help of 3M technology has been improved on all of my battery drainers. No more failed connections using conductive epoxy!

A mini slide switch selects between two levels, set at 20mA and 120mA. After a lot of testing using no less than 7 different current sense resistors, this is what I determined was the best range for the size and heatsinking ability of the PCBs. It provides a good balance of brightness, and does not suffer from heat build up. (At 200mA, it got hot quickly, and I worried about reliability.) The 120mA high level is sufficient to read by, and the 20mA setting will allow for navigation in a dark room. The circuit can handle voltages up to 5V, so anything from an AA cell to a freshly charged RCR cell as a power source. I would like to 3D print a diffuser using clear PETG, but so far the filament is printing a milky white instead of clear. Definitely more tweaking required.

The LED circuit board was designed to accommodate three Nichia Optisolis or 5mm LEDs. The Optisolis LEDs provide a surprisingly wide distribution of light, even without a diffuser. However, the three 5mm version didn't turn out quite as planned. It requires the use of high current 5mm LEDs, and I had to trim the skirts from the LEDs where they touch. I will remove the pads for the 5mm LEDs on the next board revision, and use them for a 3535 LED option.

I have not yet delivered the lanterns to my aunt's friend, as I was hoping to get at least something to cover the LEDs for long term durability. Once I calibrate my e-steps and get the proper PETG temperature, maybe the clear filament will print more reliably. This is part of the reason why I had considered the use of the 5mm LEDs. The 5mm LEDs shown below are Nichia LEDs that have a maximum current rating of 70mA, vs. the typical 25mA. At 120mA, standard LEDs would be seriously overdriven, even with the enhanced heatsinking on the PCB. I am looking forward to what my aunt's friend thinks of the lanterns, and if they are versatile enough for her off-grid lifestyle.

RFEZxiA.jpg


Closeup showing the micro slide switch.
XiGjAAg.jpg


Multiple battery support. My aunt's friend charges 18650 and AA NiMH cells with a solar charger.
kqPEcbp.jpg


The magnetic battery contact with the 3M conductive adhesive tape.
8X55ATA.jpg
 

xxo

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Looks good. I like how you got it to work with different batteries.

The clear filament is always going to look cloudy when you print with it, which is actually a good thing for a diffuser.
 

jabe1

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Wow!, quite the upgrade from your old battery drainers!
BTW, I’ve had a drainer running almost continuously since I purchased it...
 

datiLED

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Looks good. I like how you got it to work with different batteries.

The clear filament is always going to look cloudy when you print with it, which is actually a good thing for a diffuser.
Thanks for the tip on the clear filament. I might try printing a diffuser to see how it goes. I have some high strength clear 3M bonding tape that would be perfect.
The AA and 18650 support was one of the requests. She wanted built in Li-Ion charging, but I didn't want to mess with that. She can use her solar charger.

Very neat! You are a saint to take that on for fun. Wowzers.
We'll see how the lanterns go over. I have been using them at home, and the ceiling bounce with the 2700K Optisolis LEDs is amazing.

Awesome ... and using Optisolis, no less !

:goodjob:
The Optisolis size and lack of dome were perfect for the project. I had some left over from another project, and designed around them. The neutral CCT and high CRI worked out really well. The 4000K version appears brighter, but I definitely prefer the 2700K.

Very cool. The voltage versatile is awesome.
That was one of the requests. I had already been experimenting with the IC, and adapted it to this application.

Wow!, quite the upgrade from your old battery drainers!
BTW, I’ve had a drainer running almost continuously since I purchased it...

It is the same size as the original battery drainer, too!

It is funny that you mention the continuous running with the battery drainer. I have had several people tell me that they have been running a battery drainer 24/7 since receiving them.
 

archimedes

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Wasn't clear to me if these were ever going to be produced in quantity, but for sure I'd be interested in the Optisolis version
 

CR888

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I am sure I'm missing something but why not get an Olantern by Olights, you can charge it from any USB source, powerbank etc. Or an LT1 with 4x18650 cells that can be recharged from solar. Great job I guess I'm just missing the point.
 

thermal guy

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With these “drainers “ you can use damn near dead cells and have a light. No mixing two or more cells with different voltage which could be a bad thing. These will also run at a much lower voltage so you can suck the battery dry.

I’m one of the guys that have been running them nonstop since I got them and they are awesome. If your into lights then you probably have many cells that are 1/2-3/4 depleted. That’s where these come in handy.
 
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scout24

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Archimedes- It wasn't clear to me either, just wishful thinking and hoping to get in front of the curve... :grin2: :thumbsup:
 

Lynx_Arc

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I am sure I'm missing something but why not get an Olantern by Olights, you can charge it from any USB source, powerbank etc. Or an LT1 with 4x18650 cells that can be recharged from solar. Great job I guess I'm just missing the point.
I guess you missed the one on the right running off a Duracell AA alkaleak battery. Essentially wide voltage range and two output levels plus very compact. What is needed is a flexible or at least a right angle head so you can "point" it either sideways or even use it as a table lamp.
I'm glad the low output level is 20 lumens instead of 1 lumen as I've done the 1 lumen LED battery drainer and the amount of light is only useful as a night light and you can buy AC night lights that run all year for about 25 cents. A lantern is a lot more useful overall and 120 lumens high is a respectable output in a small lantern too many cheap small lanterns barely do 100 lumens and take 3 batteries to do that and run often a lot longer than needed for the size. This could also be run off USB power but would need some sort of adapter.
 

datiLED

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When you decide to sell these, please put me on your list for two. They look fantastic. 
Once I get the diffuser sorted out, I will definitely need to do something to recover some of what I have put into these.


Ditto


Wasn't clear to me if these were ever going to be produced in quantity, but for sure I'd be interested in the Optisolis version
In quantity, no. They are hard to build due to the size. I will be building more in the future once I get the 3D printed diffuser worked out.


PayPal is at the ready when these are available. Great work.
Soon, I hope. I hope to mail the first lanterns to my aunt's friend in the next week, or two.


I am sure I'm missing something but why not get an Olantern by Olights, you can charge it from any USB source, powerbank etc. Or an LT1 with 4x18650 cells that can be recharged from solar. Great job I guess I'm just missing the point.
The idea wasn't to go for a large, blinding powerhouse. This is more about balancing efficiency and quality of light in a crazy small package; it is only 15mm in diameter. It works on basically any single cell with a voltage under 4.2V.


With these “drainers “ you can use damn near dead cells and have a light. No mixing two or more cells with different voltage which could be a bad thing. These will also run at a much lower voltage so you can suck the battery dry.


I’m one of the guys that have been running them nonstop since I got them and they are awesome. If your into lights then you probably have many cells that are 1/2-3/4 depleted. That’s where these come in handy.
Exactly!


On low, these will perform a lot like the original battery drainers, with a greater spread of light. However, unlike my original battery drainers, these have a high level that is considerably more powerful. They will provide a good amount of light at the expense of runtime. The intent is for an ultra compact lantern that has the option to consume whatever cell you have available.


I guess you missed the one on the right running off a Duracell AA alkaleak battery. Essentially wide voltage range and two output levels plus very compact. What is needed is a flexible or at least a right angle head so you can "point" it either sideways or even use it as a table lamp.
I'm glad the low output level is 20 lumens instead of 1 lumen as I've done the 1 lumen LED battery drainer and the amount of light is only useful as a night light and you can buy AC night lights that run all year for about 25 cents. A lantern is a lot more useful overall and 120 lumens high is a respectable output in a small lantern too many cheap small lanterns barely do 100 lumens and take 3 batteries to do that and run often a lot longer than needed for the size. This could also be run off USB power but would need some sort of adapter.


Not 20/120 lumens, but 20/120mA. Per the Optisolis datasheet, the output is approximately 8 lumens and 42 lumens. However, the high setting appears much brighter than a light rated at 45 lumens. By contrast, my original battery drainers are in the 8+ lumen range (depending on LED), but will light a room sufficient to navigate. That is using a "dead" cell which continues to put out a declining light until it drops below the 0.6V range. The lanterns will not go as low on high, but do a really good job of draining cells on the low setting.


The lanterns were purpose built for someone living off grid, using only solar to charge cells. They have AA NiMH and Li-Ion cells. The emphasis is on extended runtime with a respectable brightness. As with anything, there has to be a compromise. I visually selected the high and low settings after testing a lot of current sense resistors in circuit. In testing, I gauged whether I could read or do other tasks efficiently. The 200mA setting was only marginally brighter than the 120mA setting. But, it made the LEDs heat up in short order, as the heatsinking ability of the copper surface area is limited.
 
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