SWIFT Solar Wide Functional Headlamp, developing and discussing.

Hey there! To begin with, I would like to say a short foreword about my project, it’s non commercial but more hobby etc.

Preface
A few years ago, I started to develop a solar powered powerbank, it was a first sheet of paper, not perfect due to some disadvantages: the linear charger bq24210 couldn’t provide a real mppt and as a result maximum efficiency. The main place of applying is hiking and usage in city. In order to feel comfortably during the active outdoor, a portable solar panel must have medium size, therefore efficiency issues take 1st place. I’ve learnt a lot about the solar energy ever since. Of course, there’re other ways - lithium bucket or large solar panel, it’s not for me.

Soon after, I’ve met the guys from fonarevka forum and things changed for the better, my heart lighted up with flashlights :slight_smile: That was dark times… 2013 you know…, a lack of light had been feeling as never before. I started to think… how is it possible to combine all this function in one device? The components were found, sharp issues solved, so let’s have a look on it.

Starting
The main idea and philosophy of such multi functional device takes their roots from simple criteria: it must be optimal and rational comparing to price, efficiency and weight at least for outdoor and traveling. Unfortunately specific devices cost rather expensive and often don’t give us enough functions. Schemes of the boost converter, mppt li-ion charger and led driver united together are allow to get better efficiency at lower price of components, by the way the only one construction and power source is required instead of a few separately ones. Reliability, convenience and quality is also important. You may agree with me, upgrading each purchased device, that manufacturer offers is not cheap.

The first examples didn’t survive due to lack of experience and instruments. I decided to left some parts for memory.

Battery charger
Li-ion charger ZSPM4521 with a real mppt (temperature/weather independent) provides additional capability far away from traditional power sources. IC programming is achieved by I2C interface. I used Kali Linux and USbasp adapter with I2C firmware. Here is the test video, charger is supplied from the stable power source. Efficiency graph was received from IC engineers and shown below.

Internal setting provides maximum 1.6A charge current. I’ve tried to increase up to 2A but the IC temperature is highly increasing, it’s not worth. Input is protected by zener diode 6.8V. It becomes rather hot, especially on the light load when the solar panel voltage is rising.

Solar panel
Seriously, I was thinking many times about DIY portable solar panels, finally Poweradd 14W is my choice. I cut off a native dc-dc converter, now the SC voltage is about 7.1V and maximum power achieved 10W. There’s nothing to add, works perfect.

Boost converter
High efficiency step-up converter TPS61032. Cut off voltage 3V, controlled by voltage detector. The time is past, now I’m going to use the next generation TPS61235.

Led driver
A Led driver is one of the most critical parts. Thanks to custom flashlight builder “Tamagotchi”, one of the best step-down drivers for single led/li-ion is available. So, detailed description is too large, I’m not sure whether you need it or not, otherwise ask any questions. It has wide features - cut off voltage (2.5, 3V), light beacon variations, strobe lights, SoC indication, blocking the button, flexible modes, everything is adjusting through the engineering menu.

Placing all the components that generate heat in one construction is quite complicated task with some limitations. But we can improve characteristics using best end components and do not exceed the barrier. In my case led current is about 800mA, I suppose, it’s enough for headlamp. Well, there’s no perfect devices, that’s why there’re so many different flashlights on sale.

Light system: XP-L BV3-F5 but XM-L2 U3 3D planned due to larger sink pad, Carclo optics 20mm medium.
Lux output vs led temperature. Special Thanks to “Egroeg” for testing.

Conclusions
Total leakage current 20uA, li-ion can be left inside, there’s no need to worry about excessive discharging. Quality plugs is essential that’s why you can see XT30, from now micro usb is also in the past. All requirements to the efficiency are met using best end components.

To summarize, you can use flashlight, power bank, charge and discharge at the same time, assuming mppt presence, device has maximum efficiency with solar panels. In addition there’s a plug on the board for the external 3.7V li-ion.

At the moment I stuck at one point, designing 3D model. Alright I’m gonna solve it. Problems? Heh, problems is for pu*sies! The case can be made on 3D printer. When I’m asking “what is the best filament for flashlights”? Silence. Choice between Nylon or PET, also may be ABS because it’s cheaper. If I succeed, without doubts, I’ll do it. It’s gonna be an open source project. I mean, everyone would be able to print a flashlight and customization capabilities are great. Seems not bad, you would agree with me, don’t you?

Why I’m here? Fresh point of view, new ideas exchange and a little bit of motivation. To the surprise, that’s my first and the only one flashlight. Thanks to all guys supporting me.

What you think about that? If you’re enjoyed, leave comments, subscribe the channel (oh it’s not youtube) :person_facepalming: Anyway, you’re welcome! :slight_smile:

Outdoor
What can be better than love and respect to the nature? Furthermore we depend on each other. So that, lifestyle determines a lot. On my mind, everything should be in moderation, especially while traveling and solar panel with a wide functional device could give us more freedom. I’ve seen different wonderful places but definitely Crimea is on the 1st place in my heart.

References
Theory is everything. For those, who wants to learn more about the solar energy, I would recommend to acquaint with this thesis. It reveals basics (secrets) of solar energy efficiency technologies. Material understanding does not require any special knowledges, overview is starting from the beginning step by step. In my time it helped to satisfy my thirst in questions.
” MPPT Algorithms for Photovoltaic Applications “:https://drive.google.com/file/d/0B5UZoGmkPR9UWnZlWjVKRUF1c3c/view?usp=sharing

Debug path
Everyone who has passed through this way, should know what is that. Sometimes the dark side rises inside me.

Update 1
What’s new? First of all a new pcb, TPS61235, 5V on average 3.5A supply load? Pff, what can be easier. Compact Attiny85V, cheaper and better driver inductor, improved layout, XT30 plugs on the board, reverse polarity protection was removed (everything depend on you, believe… I’ve learned this lesson). I had to dedome XP-L, led silicone got rust, that’s the 4rd prototype pcb, I’m not surprised, so the time has come.

I wish, I could push the button and turn back the time. TPS61235 chip got burned into ashes. Obivan! Nooooo! :open_mouth: Anyway the 1st start was successful, I had got 5.1V output under the load before an epic fail occurred. The rest of the scheme works well. Diy pcb soldering requires a lot of attention, time and nerves. As I said, debug path is painful. As soon as I design the final version, I will order factory pcb.

My topic on a profile 3D forum didn’t bring any results. Current issues haven’t been solved yet.
I’m pumping Solidworks skill at the moment.

If everything were so smooth, I would show you much more. Hope it’s gonna happen soon. Have a nice evening!

Update 2
What did you say, a quality power supply circuit? It’s not an issue any more. I dont know how about the photo but in reality it looks quite reliable. Obviously, that micro usb plugs is more compact but minor difference in size no matter. Of course I wish the flashlight had smaller diameter. Hope I’m on the final straight.

As I mentioned before, step-up converter got burned during debug. I’m going to order one more, when it becomes possible. It should not influence on the whole process.

The device has some functional, setting better components we get benefits in efficiency and power limit, so that typical power banks are losing their advantage. Based on needs, it’s convinient to vary amount of li-ion through the external plug. Wide functionality is getting real.

Update 3
Long time no see. I have some cookies for you :slight_smile:
Here’s a short time video, that shows end parameters after all losses and conversions. The tester was connected between the li-ion and charger. About 2PM, light clouds, 10C outdoor.
https://photos.google.com/share/AF1QipPGepxSf6utB3ppyO6c4f1jvL-cLTXcbdIFwKoO6aTbpg\_–6ZetCJFp9YHj1I7x-A/photo/AF1QipMhVcLun4cM8wYPwbxn8S8dqDwBKipb-pF2BD1f?key=QlctdDM0WjRiVmFPSmw2NXFGQ00zZzYwVGFXVnVB

We have made “fonarevka” in Dnipro on the days. That was really technical and productive meeting due to many unique customs and ideas exchange. I’m the only one who brought the solar panel at night :person_facepalming: But… it can’t be dark, where the meteor M43 is :slight_smile: Motivation raised, now I know the only one thing, we must keep going!

I will read this post thoroughly when I have time tonight, thanks for the write-up, but for the moment I was a bit distracted by the word ‘Reylight’, because we have a member here at BLF (WWEFANS) who makes his lights and special editions under the same name: ‘Reylight’.

I heard about this brand, when I google “Reylight” for uniqueness. Unfortunately my nickname is very similar. I can rename the topic if it’s necessary. Yes I’ll do it right now. SWIFT - Solar Wide Functional Headlamp.

Seems like the photos never appears at my end.
As someone already mentioned, we already have “Reylight” branded lights by our member here, and his lights are also sold with the same name over at CPF, so a new name can remove any misunderstanding

SWIFT is a good name :wink:

In simple post editor there is a little icon to add pics, click , paste link in first field, type max.100 in second field and paste link in last field to have the pics show and not be to wide for us phone gazers :slight_smile:

New interface…, it’s like a spacecraft. The first link is for phones? I’ve found a normal database for pics, eh… all night long…everything from the beginning. My apologies, I’ll try to fix it.

Can’t see the pics but sure sound interesting.

Did some fixes. Does everybody can see the photos right now?

I can see the photos now

I am glad you told me about this thread you stated, and I tip my cap to your work and creativity. Nice work!

Thanks for the positive! Hope it’s gonna to be worth it in the end, nope it’s already worth, I keep this device always with me in backpack. Unfortunately the solar panel is often stay lying in the box because there’re lots of power sockets around. But from time to time, we face the adventures!

Nice project! It is interesting to hear about how to make a light as efficient as possible, starting with the solar panel all the way to the amount of light that is produced.
I have litlle input for this because it is very much an electronical thing and that is not my subject.
Keep us informed! :slight_smile:

I do appreciate your interest! I agree, it impresses, when light - produces light. Searching for the li-ion solar charger was a challenge. I digged everything around, it’s very rare IC, even TI Instruments had nothing suitable, I wish, the charger could consume more power but 10W is maximum at the moment. All other components have strong characteristics, for example step-up converter can easily provide 3.5 A (90-97% efficiency depending on li-ion state of charge SOC) load up to 8A maximum, of course it will heat but even an average power bank isn’t always able to do the same.

Tomorrow will be the judgement day, the time to solder a new pcb has come, if something burn out, you might be the fist who hear my voice :slight_smile: Debug path is painful.

By the way, I’ve read your “Springs” test recently, find out it extremely useful. Thank you man. I decided to choose Fasttech ‘carobronze’ because of not high load currents of the single li-ion, current path of the external li-ion will come through the XT30 plug.

Efficiency is the high-ground.

Look forward to your results and further steps you take.

Interesting topic, I am also looking around for solutions to charge li-ions from solar.

Do you know about the CN3722 chip? Here is the datasheet 上海如韵电子有限公司-欢迎访问上海如韵电子有限公司主页!

Here is a ready made charge controller using this chip http://www.ebay.de/itm/181908611611

And here a review of this charge controller Cheap(est?) Lithium MPPT Solar Charge Controller CN3722 - 12v Solar Shed - YouTube

I plan to order this and use a 75W solar panel I already have lying around to charge a 3S li-ion battery pack, should work I hope.

edit: Where do you got the li-ion charger from?

If you can make your led engine fit some headlamp that already exist, it can be popular, you will be able to sell them as transformation kit.
Otherwise making plastic cases on 3D printer by 1pcs will cost more than zebralight for 95% of users.

Yes, it’s well known from me. But as for the efficiency, it doesn’t have a real mppt, so if weather conditions changing, device won’t track solar panel’s IV curve, basically this device is functioning with a static mpp instead of tracking. It will work and not really bad, anyway there’s an issue whether it worth to use advanced system, that in a few times more expensive. Check here, some good fully integrated solar chargers.
http://genasun.com/products-store/mppt-solar-charge-controllers/mppt-for-lithium-batteries/

I’m just worrying about rather high system power, you know… pcb will heat. I’m not sure that it’s possible to load this charger more than 25W without radiator, you should take it into account. As a rule power is growing together with lossless therefore a total efficiency should be in a priority here or not really if you have enough solar power. You know, if it weren’t for so expensive solar W/$ and mppt controllers cost, everything would be ok, that’s why we have to find balance.

I know one man, who’s actively exploiting CN3722 at the moment. As for me, I always read his blog with passion, especially the electronics chapter, but there’s no english language. Here’s is the link. Just try to translate, hope you’ll find it useful.
http://www.shpilev.net/archives/663

Well, I was lucky and bought a few pcs in my local store, when it costed around 3$, but Zmdi company is rebranding to Idt, that’s why this IC haven’t been selling so far. The total cost of the charger’s pcb is about 8$ including all recommending components. You may find test boards on mouser or farnell but they cost quite a lot.

I wish, I could… Look, there’s no suitable headlamp having enough place inside for all this electronics. I might find some examples but they’re not wide spread, their quality and price deserve better.

About the price, I don’t know, what’s a real self-cost of an average zebralight. There’re much more functions in my device, that’s why it’s hard to discuss price difference. It has already cost me 45$. I can’t mark any benefits of zebralight headlamp compared to my fully completed device, except one - more lumens but happiness lies not in lumens.

That’s really nice, when you’re not tied to a certain flashlight. 3D printing has began available as never before, even a kid is able to create a simple model. Prices are mainly depend on the filament and weight. I’m going to spent about 10$ for the first example, it’s not really expensive as seems. No matter, you order 1 pcs or 20 pcs, technology is the same. Therefore I suppose that’s a right direction. After making a 3D model, we could back to this point.

If I were you, I would prefer this charger (link below) to CN3722. Just because it’s TI, pcb probably has better thermal perfomance. I know very well this chip, that was my first acquaintance with this topic.

I would reccomend you to check YZXstudio DIY on Taobao. I have no idea what the voltage of your solar panel, it’s all up to you.
https://shop35123736.world.taobao.com/?spm=a312a.7728559.2015080705.3.JFsoJ7

Try this one, it’s must be the same and still available on sale. There are also chargers for Ni-Mh and Supercap.
http://eu.mouser.com/new/semtech/semtech-ts52001/

Thank you for your suggestion with the BQ24650. This looks like a good match to my 75W panel.

Edit: just ordered a board with this chip