I've been reading a bunch of blogs this fine Earth Day morning and have noticed that most of them are posting little write ups about green solar powered USB gadget chargers. They're all quite nice, but also quite expensive. I don't think I've seen any for less than $60, and I've not seen one that really suits my style.
Instructables has quite a few guides on how to make Solar USB Chargers, including the very well done guide on how to combine a Lady Ada Minty Boost circuit with a solar + lithium ion battery. Great, but a bit expensive to make and not a very simple project for the weekend DIY person.
Well luckily for us I know how to make one for under $20 that is better in nearly every way and also completely fits into an Altoids Tin. Covert style.
(If you want a more powerful USB Charger, a Heavy Duty one, I have an instructable for that as well.)
Instructables has quite a few guides on how to make Solar USB Chargers, including the very well done guide on how to combine a Lady Ada Minty Boost circuit with a solar + lithium ion battery. Great, but a bit expensive to make and not a very simple project for the weekend DIY person.
Well luckily for us I know how to make one for under $20 that is better in nearly every way and also completely fits into an Altoids Tin. Covert style.
(If you want a more powerful USB Charger, a Heavy Duty one, I have an instructable for that as well.)
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Signing UpStep 1: What You Need
Parts:
USB Charging Circuit
Solar Panel 4V or greater
AA Battery Holder
AA Rechargeable Batteries
1N914 Diode
Altoid Tin (or whatever)
Wire
Tools:
Soldering Iron
Solder
Tin Snips
Melt Glue Gun and Glue
Tape
Cost is less than $30. I can make one for under $10 when I buy parts in bulk. I have a kit available at my website BrownDogGadgets.com which has everything you need to make this project. Also, if you're lazy, I do sell made versions in a variety of tin styles.
USB Charging Circuit
Solar Panel 4V or greater
AA Battery Holder
AA Rechargeable Batteries
1N914 Diode
Altoid Tin (or whatever)
Wire
Tools:
Soldering Iron
Solder
Tin Snips
Melt Glue Gun and Glue
Tape
Cost is less than $30. I can make one for under $10 when I buy parts in bulk. I have a kit available at my website BrownDogGadgets.com which has everything you need to make this project. Also, if you're lazy, I do sell made versions in a variety of tin styles.
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thanks.
Bill Metrey
Thanks
b.t.w im using a 6v solar panel
Check out the site info right here: http://waterbattery.com/
A cheaper site to buy from: http://shop.conics.net/nopopo-3pk.html
I hooked up two cells in a series and connected it to two AAs and then those to the circuit board, even tho I am not 100% sure that i am hooking them to the correct place, because it does not have a + or -, so I am just trying to use common sense and I picked a place :). Currently the charger is not working, so i am trying to evaluate. Hope this was understandable.
The circuit I uses takes 2-3V (such as 2 AAs) and boosts it up to 5.
Two completely different circuits.
I emailed you about all this as well, so check your inbox.
It's a connivence and price thing when you choose batteries. Lithium are better, but are more expensive and are more work to wire up. NiMh are cheap and easy to use, but are not as effective.
Or you could just take a 2AA battery pack and just touch the wires to the board. If it works, you have things right. If not, switch the positive and negative spots and try again. (Guess and check)
Thanks so much!
Find that that turns 2 or 3 AAs into 5V USB.
(Not a wall one. Bad idea.)
Or you can just stick some batteries in and then plug a gadget in.
Though with this small of a solar cell a lot of USB stuff won't charge directly from the solar cell, they need the batteries in there as well to augment things. (Which is why I have more heavy duty versions of this charger setup with more powerful solar cells.)
Though to be honest the best solution is 3 AAs in a series to give you 3.6V, but then you'd need about 5V coming in to charge.
The switch should be all the way back. Towards the positive and negative terminals in the "rear" of the board.
When in doubt, try using regular AAs to see if it works. Often the rechargeables will be "low" and thus charging won't happen.
You can email me directly off the site. It's a lot easier to get ahold of me that way.
I have no idea what to say unless I was to take a look at the charger you used and how it was wired up.
Little garden lights generally, from what I've found, put off between 2 - 3V of power. Which seems about right as they charge up a single AAA battery inside (AA if you're lucky). The big problem with them is their current flow is usually really low.
Wiring up two in a series (like using a 2 AA battery holder would do) will give you enough to work the USB boosting circuit just fine.
You can always wire in 3 or 4 in a series, that works even better. Though 3 would really be all you'd need, a 4th one would be overkill.
Some customers have wired up two of the 2 AA battery packs together, which does a nice job of boosting capacity while also maintaining a higher voltage longer. Though that makes for a tight Altoids tin.
http://www.ebay.com/itm/DC-DC-Converter-Step-Up-Boost-Module-3V-to-5V-1A-USB-Charger-for-MP3-MP4-Phone-/271023697418?pt=LH_DefaultDomain_0&hash=item3f1a456e0a
(It is probably the same one I played around with, but I know there are like 3 or 4 variations of it on eBay and I've not tested them all yet.)
http://www.ebay.com.au/itm/4-2V-12V-11200mAh-Power-backup-Solar-Battery-Laptop-any-usb-port-devices-/260964887858?pt=AU_Solar&hash=item3cc2b82d32
http://www.ebay.com.au/itm/Universal-USB-Solar-Charger-Phone-MP3-MP4-Camera-Solar-Battery-USB-Charger-/330706173012?pt=AU_MobilePhoneAccessories&hash=item4cff9fbc54
This is instructables. For people who want to build their own things. Many projects on instructables you can buy similar things in stores, but people come here to learn and create. Not to find cheap deals.
There are lots of great solar USB chargers on the market. Some are quality and some, like the one you linked to, are cheaply built and function cheaply. I've taken apart enough of them to know that there is a big difference between a $10 charger and a $50 charger.
With three rechargables it charges my Android phone up to the point that the batteries reach abour 3.7 V, then the red LED (I kept it on) qives a few quick flashes and (although output through USB still measures 5.15 V) charging stops. Do you have any idea what could be going on?
I have two questions for you:
1) What does the white "useless" LED on the USB Charging Circuit really do?
2) Is there a easy way to add a LED that will light when the solar panel is charging the batteries?
Thank you, love your educational tutorials :)
2) You could always add in an LED in parallel, but you'd be wasting valuable amps. You'd want a switch or something to turn that on and off. A blue LED would be good as it's higher voltage. (Though this is a poor indicator overall.)
thanks
-Doctordv
Fact: It will take you more than 10 years to pay back
Solution: Using Surplus Solar Cells You can get pay back in 1-2 years
There is an Engineer from Chicago his name is John Sommer
He explain it All in his diy solar panels Blog Search for him using Google
Type "top diy solar panels" Open the first Result.
Note: Ignore the adds at the top.
I am looking to build a slightly different version of this instructable, but with supercapacitors instead, to make this "super-green". Do you know if it would be possible to just use supercapacitors to completely replace the batteries? Even if it would only work while in the sun, that would be fine with me... Any help would be great!
The biggest environmental impact will be the energy used to make the refined silicon for the solar cell, most likely from coal burnt in China. Switching to super caps would not resolve that.
The only downside is that super caps cost a lot of money compared to just using some AAs. Plus because of how little power this thing uses a set of AA batteries would last a very very long time.
http://www.ladyada.net/make/mintyboost/changelog.html
Apple has apparently changed and rechanged their load protocal to make it difficult to charge. Adafruit has tried to keep up with it.
You also don't need to worry about overcharging. We're not throwing enough current at the NiMh AA batteries to overcharge them.
If it makes a difference, I'm using the same USB from the same emergency charger as you did.
Thanks in advanced.
I dont know if this curcuit would handle the 5watt DC power source (beyond my EE knowledge)
Also, I know heat will damage the batteries for sure, however, again I'm not sure how hot exactly they can get before it damages them.
My situation is that I live in Phoenix Arizona and I really want to make one of these, however, I don't know how long I will be able to leave the charger in the sun without it getting damaged due to excessive heat. It's really the solar cell that I am concerned about as I am sure I could find a way to keep the batteries fairly cool in the shade while the solar cell is in the sun.
Do you have any suggestions?
But yes, the batteries may be a different issue all together. Keeping them cool might not be a bad idea.
Try this out. External solar cell, long wire, jack and plug setup.
http://www.browndoggadgets.com/store/solar-kits/heavy-duty-usb-charger-kit/
Help? :/
Does it create enough power to do this?
I would like to use the 4v solar panel or do I need a larger panel?
The solar cell isn't powerful enough to power an iPod all by itself.
A larger cell, one outputting over 200mA, will probably be enough.
I just posted a new Instructable on how to make a Solar Charger using a big solar cell along with a Jack and Plug setup. Might be up your alley.
(Though I'm guessing you're going to be ok.)
Two solar positives together, then the diode off of them.
Well I recently tried with a new batch of these circuits and my iPhone 4 charged perfectly. Big surprise to me.
If you're going to be using this with only an iPad or iPhone you might want to use a different circuit. I have one that has a retractable iPhone/ iPod/ iPad cable on it, as opposed to a USB port. Handy.
For example, if i wire 2 packs of batteries, each cell with 1.2V and 2000mA together in parallel to make a combined total of 2.4V and 4000mA, should i buy a solar panel with a current output of 200mA or 400mA for best results?
Thanks!
Parallel = 1.2V at 4,000mah
Series = 2.4 at 2,000mah
10% of total capacity.
I've gone over 10% before, it really depends on your batteries and how trusting you are of them.
So in your case you'd want to use two battery packs, with a total of 4 batteries. Giving you 2.4V at 4,000mAh.
Go with the bigger cell. You'll never ever reach your max power for solar anyways.
will the 12v be sufficient? ... too much? will the 100ma allow me to charge the batteries in a reasonable amount of time given that it's solar trickle charge we're working with?
Meaning a 12V system should have at least 18V of solar panel in it.
So if you're doing 9.6V you should have at least 14-15V of power.
It sounds like I can't very well blow anything up with 12v so I'm going to proceed with wiring the mock up and testing on the next sunny day.
also I might add, the panel only puts out 100ma, and that for 2500mah batteries would take forever so i've got two panels. Should suffice. The idea is that i can strap the device atop my backpack while hiking, trickle charging as i do, and then flip open to reveal both panels when the opportunity presents itself.
The ones I bought for the yard claim to be 4x bright. What would be the proper way to determine if I need 1 or 2 solar cells of these? Just test output of the panel with a voltmeter?
You'd still need to get all the other parts. AA holder, 2 AAs, diode, wires, charging circuit.
Plus you should really use a multimeter to figure out what the voltage of your solar cells is. You need a combination that is greater the 3V. The bigger the better.
Long story short you just need to find a newer charger that has this problem fixed.
Question: Do you know what kind of capacitors are on that circuit...just curious.
-Relient Owl
The caps just help the power flow more smoothly in the circuit. They're not for storing large amounts of power. That is why we have batteries in the circuit. Though some people have instead used some massive capacitors instead. They're nice, but cost an arm and a leg.
I don't understand two things:
1) i have a lithium batthery 3.7V 2800mAh with a internal circuit for the protection: can i use it in your circuit? I need an battery charching circuit for it? Can I disassemble something to use?
2) if i put in parallel a simple AA ni-mh battery, the 10% of their maximum limit for charging it from a panel will double it? So i have a solar panel that give me 700mA, so if i put in parallel a 2200mah battery to arrive at 6600mAh, is it sufficient?
Thanks a lot.
You would need a small changing circuit to handle your Li-ion pack. You can pick them up most anywhere. For instance I know adafruit.com has some that work well in similar circuits. Otherwise ebay is your friend.
I wouldn't try and take a li-ion charger out of something else. Just buy a small circuit from somewhere. Adafruit.com has directions on how to hook up a li-ion pack to a very similar circuit to the one I use in my project. Seriously check out her site.
Bye!!!!
Also, I saw a video on youtube and this guy used 4 AAA's. Which is better, AA's or AAA's?
Wall chargers step down voltage, we need to step it up. This means you need a little emergency USB charger that uses 2 AA batteries. It'll boost the voltage up to the right levels.
(Assuming they're completely dead, though you'll always need about 10% more time than needed to charge up NiMh in my experiences.)
You'll also need full sunlight. If it's a bit cloudy then charging will take longer.
If you want fast charging (like very fast) you're going to need a bigger solar cell or several small solar cell. Solar is great, but you have to know it's limitations.
Plus your batteries will never be 100% dead (well, usually) so you'll never need to charge them up all the way.
Shoot, I have a few hundred in my basement and I want more...
http://www.ebay.com/itm/Emergency-charger-AA-battery-powers-USB-MP3-mobile-/150659931898?pt=Other_MP3_Player_Accessories&hash=item2314081efa#ht_4786wt_1344
Just ebay "emergency USB charger" and I believe any of those work that are portable and take two AA batteries.
I also have the circuits on my website as well if you need them.
im assuming that the batteries allow the usb to charge even if there is no sunlight (like the minty boost) and the the solar cell merely charges the batteries it works fine when i hook it up to a 9v (i do no have the solar cells yet) but when i try to use 2 AA batteries it doesnt work.
if you cannot tell i am a complete noob. the only thing that i can thing of (and it may totally be laughable) is that since the 12v dc is higher than the 5v ubs there is some mechanism on the board that lowers the voltage. that or im just a moron and i put the thing together wrong.
Smaller cells, less batteries, and less overall weight.
could i use a diode with a large voltage drop?
or
A diode with a small voltage drop then a resistor?
also the batteries wont stop charging will they? will the batteries become damaged if device is left in the sun for too long?
Use a 1N914 diode.
No resistor needed.
The batteries will be fine once they top off. You don't need to worry about over charging them.
I do say to use one greater than 4V, otherwise you'll not be able to get the batteries charged up.
Now a battery vs a solar cell... The thing with solar cells is that it's rating is the "optimal" rating. Noon on a sunny day. Are you going to be getting that at all times? Probably not.
If you're really really worried you could always put in a a nice SPDT switch. Flip it one way to charge just the batteries, flip it the other was when you want to power the circuit. That would make things very safe and allow you to use any solar cell you'd like. (Just don't overload the battery.)
Something to keep in mind is that unless you plug a USB device into the circuit, it doesn't become active. The USB device completes the circuit, which is why the circuit doesn't suck power when charging.
What is happening is that the batteries and solar cell are making a circuit, which is charging up the batteries.
Long story short you shouldn't worry. Just watch your charger and test it out. That and don't put it on top of any piles of oily rags in the middle of a fireworks store. Just in case.
Correct me if im wrong?
Im thinking of using a lion polymer btw, not sure yet.
Im asking if we can charge NiMh safely just like that "directly connect the solar panel to the batteries' (NiMh) ends".
This one: http://www.browndoggadgets.com/store/circuits/usb-charging-circuit/#!prettyPhoto[494]/0/
Just make sure the circuit you're using is made for use with new Apple products. They have special requirements.
I just have a few questions
the 1N914 Diode. Ive been to many stores. Every 1N914 is different. What one should I use?
And I see on you're site it doesn't charge New apple devices. Do you think there's a way to make a universal one? IE: not just Apple or just USB
Oddly the circuit I've been ordering in now seems to work with newer Apple stuff. Or at least with my iPhone 4. You could always just fine an "Emergency USB Charger" for cheap online and see if it works with your Apple stuff, and then gut it.
For the Emergency USB Charger, that's a great idea, You get all the components just need to modify it for Solar.
Thanks Edd.
I know that you need a complex charging curve to charge Li-Ion batteries but I was going to use a charging IC for that.
Apart from that is there any reason this might not work?
Solar Cells > Charging IC > Li-Ion > USB Converter > Phone (etc.)
Ni-Mh are comparatively expensive and lower in capacity, and thicker :(
You need a circuit that boosts the voltage, not drop it.
You can also take one out of a solar garden light, provided it is at least a 4V cell.
I get mine in bulk from China.
The circuit boosts the voltage up to the 5V that USB requires. Which is how we can get away with using two AA batteries.
The speed at which the batteries recharge is controlled by the amperage, or in this case the mA. The higher the mA the faster the battery charges. Now on the flip side you need a certain voltage level, in this case we need at least 3V power to charge the batteries. Now we user a higher rated solar cell because sun is a tricky thing. A 4V cell gets 4V in the best conditions only, usually less. The higher rated your cell is for voltage the less sun it needs to get that minimum level that you need.
Overall the best all around cell is the 4.5V. The reason most people get the 4V is that the 4V fits into an Altoids tin. The other cells do not.
You can replace the batteries at any time. In a pinch you could use alkaline batteries, just don't try and solar charge them. Doing so will cause the alkalines to leak or to explode. In fact if you were to make a habit of that I'd suggest that you put a switch on the inside to cut off the flow of power from the solar cell to the batteries. Just to play it safe.
The USB/DC LiPo chargers (like this one: http://www.adafruit.com/products/280) can do that, but I didn't know if there was something else I could incorporate into this to give it that ability? I guess a USB charging circuit that would have USB/DC input on it that works with AA battery chargers.
thanks again!
No point making what you can buy for next to nothing.
I was under the impression that the usbport was power-out only and wouldnt change the batteries directly.
Thanks again
A customer of mine added a power plug to his so he could plug in a wall adaptor. That was he could charge up from the wall.
Though to be honest a much much easier solution would be to take the AA batteries out, put them in a "smart" wall charger and then put them back in. From what I've seen you can get AA chargers that will charge stuff up in 2-3 hours.
will the batteries be damaged with a voltage that high?
if i were to use 2 sets of AA in parallel would this dissipate the current across the two sets so i would have 5.5V at 50mA for each set of AA's?
Two sets of AA in parallel would only increase the capacity. So instead of 1 pair at 1800 mah you'd have 2 pairs at 3600 mah.
So think of it as 100 ma over 3600 mah of battery.
I'd personally add the extra batteries. You can never go wrong that way.
A lot of it depends on how easy they are to remove... I've broken a few solar cells due to them being too tough to get out of the solar light.
Also, you need to be aware of the current on these cells. They may have a high voltage, but probably have a low current. Not a big deal for the lights as they have small batteries, but we want to change up larger capacity batteries. This is why getting a solar cell with a higher current (miliamp) really helps things out.
Thank you for your instructable, but whcih part do I nedd of my ''cheap usb charger from ebay''?
Thank you, pic below ;)
Just hook up the batteries, solar cell, and diode.
It appears as though the circuit you used is one from a prior device and not one you mocked up and soldered yourself. I am curious what device you pulled the circuit from as i am interested in making once of these badboys myself. Since im relatively new to DIY electronics i want to follow your walkthrough as thoroughly as possible.
Thanks for your time and contributions to the greater good.
thanks!
A 4 holder would put the voltage at 6 volts for regular batteries and 4.8 volts for rechargeable batteries. The capacity would stay the same. Plus the 4V panel wouldn't be able to charge 4.8V worth of batteries.
What would be better would be to wire in two sets of 2 AA holders in parallel. Then your capacity would double but the voltage would remain the same. The downside would be that it would take longer to charge up. You could then always ad another solar cell and put the entire thing in a bigger case.
http://www.sciplus.com/singleItem.cfm/terms/12871
It says it's 4.5 volts, and it's 2 3/8" square.
Also, how do I wire the 2 AA holders in parallel? Just meaning solder 1 to the other, then the next one to the circuit?
thanks!
http://www.browndoggadgets.com/parts/solar-cells/4-5-volt-80-ma-cis-solar-cell/
What you just described is wiring in a series. To wire it in parallel you would hook both positives from the battery packs to the positive intake of the circuit, and both negatives from the battery packs to the negative of the circuit.
Like a 4"x4" solar panel?
Also, awesome instructions. I found a great place where you can get 2V solar panels off of garden lights for $1/piece, so I'll definitely be trying a lot more of your creations out.
In this project yes, because we need 5V worth of power to charge up USB devices. The circuit boosts the 2.4Vs from the rechargeable batteries to 5V, as well as regulating the current.
In other projects no. You could always use a whole bunch of batteries to achieve a voltage greater than 5V, and then use a voltage limiter to keep it at 5V. You'd also need a bigger solar cell to charge up the batteries at a higher voltage.
The circuit just makes things a whole lot easier and a whole more compact. You can use a smaller number of batteries and a smaller solar cell to charge them.
You could hook up several 7V @ 60ma in parallel would increase the speed of charging the batteries. You would need a diode for each solar cell you used (or wire it up to all use the same diode).
Since we're only "trickle" charging the batteries we have to be careful not to overload them. They can only take in, at the most, 10% of their capacity. So if your batteries are rated at 2000 mah you can only throw 200 ma at them. Otherwise they'll die. Thus the problem with such a simple circuit.
If you want to charge up stuff faster you may wish to use a more complicated setup of a lithium ion battery and a lithium ion battery charging circuit. Then you could use a much more powerful solar cell (say one with 500 ma of power coming down) and get a faster charge going on. There are a couple really good instructables out there on how to do that if you're interested.
I like taking the more simple approach because the less complicated it is, the less can go wrong. Especially when you're making things yourself.
Thanks for the help and keep posting 'ibles...yours are great!
Thank you very much for the nice instructable!
The other problem is that iPhones (3GS and 4) need a special USB circuit to charge from. Long story short most USB chargers won't work with an iPhone unless they're made for use with them.
In fact my USB chargers won't work with them. My iPhone 4 has been very sad because of it.
Also your solar cell doesn't have enough current to charge up an iPhone. They require at least 500 ma to charger, which is why most chargers use internal batteries. Solar cell charges internal battery, battery power is sent through a booster circuit to charge USB device.
I did, however, find a circuit that works for iPhones and that would work for you.
http://www.browndoggadgets.com/tins/solar-altoids-iphone-ipod-ipad-charger/
I'll be putting together a kit for it as well once I get more parts in. Probably in the next week or two. You would need the circuit, rechargeable batteries, and a battery holder. Your solar cell should be just fine.
Thanks!
Yes, higher voltage cells mean you don't need as much light to charge stuff (I think).
For example, if you're charging 2 AA batteries you need at least 3V of power to charge them. Well if you're only using a 4V solar cell you need full sunlight to get that 4Vs. However, if you're using a 12V cell you only need 1/4th sunlight to get 4Vs out of it.
Increasing the capacity (mah) of the batteries would give you more charge, but would not increase the recharge rate of your gadget. The recharge rate is determined by the charging circuit as well as the internal battery of your gadget.
If you increase the capacity of your batteries that also means it will take longer to charge those batteries up via solar. So either you'll need more sun or you should get a solar cell with more current (amps, or in small cells miliamp (ma)).
I tried beforehand to rip apart an AC to USB converter like for a wall charger, but not only did I almost slice open my hand (Safety Third!), but I pulled the darn thing out, and don't know what to make of it or how to split off JUST the USB converter.
Also, I've attached a pic of the converter I cannibalized, if anyone out there in DIY-land can help make sense of it. I'd like to salvage it, if I can.
Keep up the good work! I'll definitely be attempting more of these projects.
You don't want to be messing with that as 95% of what you see is probably useless to this project. Plus if we're making a solar to USB we need a boost circuit, not an AC to DC circuit.
If you can find a busted battery powered cell phone charger you could always steal that circuit (it's a booster) and then wire it up to a USB port. That should work exactly the same as the circuit I'm using. I used to see those emergency cell phone chargers at every convenience store in Japan, but I'm not too sure where you'd find one around here.
Otherwise I have the booster circuit for sale on my website browndoggdgets.com ($9), or you can build your own from adafruit.com ($20).
A booster circuit is just a lot more simple and saves a lot of room. Less solar panels needed, less batteries needed, and less solar panels needed.
Which brands/web sites do you recommend for chargers?
Try amazon.
In many ways it's just heaps easier to buy something and take it apart.
Thanks again.
http://www.instructables.com/id/MintyBoost!---Small-battery-powered-USB-charger/
It tells you how to make one there. You'll be hard pressed to buy the parts cheaper on their own. Parts are always quite cheaper in bulk.
Plus it's summer! Summer should be all about solar.