When I got into electrical circuits and solar power the first thing I wanted to do was build a little solar powered battery charger. Only I had a heck of a time trying to find a simple and strait forward guide to doing this.
So in this guide I'll give you a bit of info on solar power and battery charging, as well as show you how to make a solar battery charger for all of $4.
If you'd like some solar panels or solar kits I have quite a few on my gadget site, browndoggadgets.com or you can also buy them off ebay or various other websites.
So in this guide I'll give you a bit of info on solar power and battery charging, as well as show you how to make a solar battery charger for all of $4.
If you'd like some solar panels or solar kits I have quite a few on my gadget site, browndoggadgets.com or you can also buy them off ebay or various other websites.
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Signing UpStep 1: What You Need
To build a solar battery charger you need several things, as well as have several tools on hand.
Parts
A clear, water-proof container. (Dollar Store tupperware with built in O-Ring)
AA Battery Holder (Radio Shack, also fits AAAs if you're careful)
One or Two Solar Panels rated 4 Volts or above
Blocking Diode (Radio Shack, or buy 100 for $1 off eBay.)
Tools you need
Soldering Iron
Solder
Tape
Safety Goggles
Some wire
Time: 20-30 minutes
Difficulty: Easy
Parts
A clear, water-proof container. (Dollar Store tupperware with built in O-Ring)
AA Battery Holder (Radio Shack, also fits AAAs if you're careful)
One or Two Solar Panels rated 4 Volts or above
Blocking Diode (Radio Shack, or buy 100 for $1 off eBay.)
Tools you need
Soldering Iron
Solder
Tape
Safety Goggles
Some wire
Time: 20-30 minutes
Difficulty: Easy
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'm now having a problem figuring out how to rig one of these up to charge 4AA's that are connected to 8 LED's and have a dusk to dawn circuit. I have 2 panels that are 4.5 volts +/-, 3.2 volt-20ma Amber LED's, but no charging circuit. I think it's best in the long run to have a full charging circuit for this project. Do you think I am correct? I also don't have a properly configured dusk to dawn circuit. Any idea's? Any help would be great. Thanks.
Your charger circuit here will have the desired effect, and for the batteries you mention, the issues with milliamps should not be a concern. The kind of series (blocking) diode is not a big deal either, since the forward drop will not matter. You may use any garden variety silicon diode, and worst case is that the diode will fail (without damaging anything else) and you are out a penny. Just be sure to pick a diode that will allow the max current from the solar cell, in your case, 80 mA, which is 0.08 Amps.
Good luck, and always, safety first. It's a great habit to have.
Now, if you have a silicone diode with about 0.6V forward drop, you have to produce 3V. If you have a schottky diode with 0.3V drop you only need to produce 2.7V.
3/2.7 = 1.11, an 11% efficiency increase. More importantly, during periods of less sunlight your cells may not even be able to get the voltage up to 3V at a meaningful charge current so that extra 0.3V margin could allow for charging for more hours per day too.
"One or Two Solar Panels rated 4 Volts or above"
If the 4-volt requirement is no longer true, then yes, it does matter.
I really shouldn't be writing instructables at 1 a.m. anymore.
Thanks!
The biggest tragedy would be for someone to have a great idea and not share it.
Hooking up in Parallel will double the current, 80 ma + 80 ma = 180 ma, but keep the voltage at 4.5 volts.
It works the same for any power source. Try and imagine the solar panels as big barrels of water. In a series the two barrels of water are hooked up one on top of the other. They have twice as much water pressure source, but can only squeeze 80 ma of water out at a time through the one pipe.
In parallel you have the who barrels side by side, each pumping out 80 ma of water, doubling the amount of water coming out, but only one barrels worth of pressure.
just a quick question though, I have 5 solar cells, 2V 50mA each, I want 6 volts and 100mA I worked out how to do 2 in parallel and two in series, but I'm not sure where to stick the fifth one to increase the voltage.
A solar panel is only as good as the least powerful cell. Which is why a single leaf falling on a solar panel can really mess up your output.
Say we have two AA batteries in series Then wired in parallel to another set.
That's about 2.4-2.8v at like...4000Mah.
What if we used a cell that is 6v @330Mah? The Mah is cool but what about voltage? If anybody could help I would be really grateful.
I picture the battery being inside the tub to minimize weathering over time, with the battery cables to the motor running out the side of the tub... whatcha thank about that?
TSC book where a man actually used some of them to change his tractor over to an electric solar power engine and he said he had more power than the original engine. I want an idea of how to make an electric engine for my lawn mower that I could run that way.
But directly powering your motor would be tough as I doubt the solar panel could put out the amps you need to drive the motor.
Also, because you're dealing with a much much bigger system you would need a power controller. It's a little box that makes sure the solar panel isn't providing too much, or too little, power. Those are rather cheap off eBay.
Again, you're looking at between $50-100 worth of setup for such a system. Not bad really.
sometimes you can get close to $200 on sale for example
http://www.harborfreight.com/45-watt-solar-panel-kit-90599.html
thats 45 watts. not much power but would put a measurable charge back into your battery. assuming a 50 amp hour deep cycle you need 650watts for a full charge so this panel "could" in ideal conditions recharge it fully in about 14 hours of GOOD FULL broad day light sunlight.
so if you were fishing for say 5 hours you could replace 1/3 of your battery capacity.
use TWO of those panels and you have something more usable. you go go till your battery dies in the morning fish for 8 hours and have a fully charged battery to get home with IF you had good broad daylight sunlight AND you tilted the panel TO the sun in the morning and toward evening to catch the most light.
http://www.ecrater.com/search.php?cid=0&keywords=60W+solar+panel&x=0&y=0
but still wow $108 for 60watts. Very very tempted. if I had $108 in the bank I would already have ordered it!
So just connect four cells into two sets in series, then connect two two sets in parallel you would in fact get 9V @ 160 ma. Then connect two sets of batteries in a series and you would get 4.8V.
It's a good idea that would work just fine. Just remember to put 4 batteries in at one time.
You'd be better off just spending the $5-10 and getting yourself some good quality solar cells. The little calculator ones don't put out much current, and some phones won't charge unless there is a certain amount of current coming in.
If you'd like some info on how to make a cell phone charger, send me a PM. I've got a couple of designs that have worked well for me.
Quite a bit cheaper than buying premade panels, thats for sure.
If I was ever to have a home built (ha ha) I would have it built so that I could easily add panels to the roof. If I even end up living in the countryside I would set up a system over several years using a combination of solar and wind (as wind will give you far more power for your $, but is inconsistant).
For the average home owner spending a couple of hundred a year on this would be possible, but it would be quite a few years before you'd see the major payoff.
That or you could set up a bunch of well geared staionary bikes hooked up to batteries and open a gym/ powerplant.
You can buy one for as little as $10, but if you're going to be doing a bunch of projects like these you'll want to buy one in the more $20-30 range that has adjustable heat.
Also be sure to get one with a fine tip, not a giant tip. This makes things much much easier in the long run.
You might also want to look at yard sales during the summer. Some of the nicer solar lights have rather powerful solar cells in them.
The one thing you'd need to watch out for is the power of your solar cell. A 1.5 - 2 volt cell isn't going to charge up more than one battery, and we still don't know how many amps it's putting out. To charge two AAA or AA batteries you'll need at least 4 volts of power. The more volts a cell is rated for the less sunlight you'll need to get the minimum voltage required to charge up your batteries.
Even when I'm just charging up a single AA battery I still use a 4.5 volt cell so that my battery will be able to charge for a much longer period during the day.
I may have missed this somewhere, but do you have to make sure to STOP charging the batteries after so long? So, if I forget that there out there on my deck, can I damage the batteries?
Also, would it be hard to add a charge controller that would handle this?
That being said I wouldn't leave them outside for two months at a time, that would be sad.
http://www.westfloridacomponents.com/mm5/merchant.mvc?Screen=PROD&Store_Code=wfc&Product_Code=DI033&Category_Code=
Along with a pretty nice solar panel I got from a VW Beetle battery charger.
It's got max power of 3.2 W, max power voltage of 18.8 V (!), and max power current of 170 milliamps.
Do these stats check out for this charger?
So yes, that diode will work with your panel, but I wouldn't use that panel for charing AA batteries.
Buy a much smaller 4 or 5 volt solar cell for this project (all you need is one, two if you want to be fancy). Save your panel for bigger and better things.
That or you can pull them from defunct garden lights, which also has worked well for me.
I have a bunch of rechargeable AAA batteries that I bought in bulk so they end up being 50 cents each. To buy them individually would cost quite a bit.
"A solar panel (photovoltaic module or photovoltaic panel) is a packaged interconnected assembly of solar cells"
its more than one interconnected cell in a package.
sounds like a solar panel to me :-)
A very simple solar panel. But one none the less!
Really. When does a device go from a solar "cell" to a solar "panel"? I wonder what the discriminating factors are.
so one cell is a solar cell.
more than one cell packaged together is a panel.
more than one panel set together is an array.
you could also have an "array" of cells a panel is essentially an array of cells.
but an array usually implies "larger scale"
To the average person there is no difference between a solar panel and a solar cell in their mind.
(For instance I asked several people today and no one knew the difference.)
http://i.imgur.com/m3ygf.png
you and i know. but average joe would not.
But as nerys say, the average joe (and my mother) can not tell the difference and probably use the two terms interchangeably.
A solar panel is a mechanical term, it puts one or more solar cells into a protective casing to ruggedize it for (outdoors usually) use. Due to shipping and handling size issues, many solar panel arrays will have multiple solar panels in them, an due to the output voltage so commonly needed, most solar panels will have multiple solar cells in them but this is changing as new techniques produce high voltage cells.
Also, you shouldn't charge NiMH above 30 C or 86 F so if it is getting really hot, like in a car in the sunlight, you will have a lower capacity from that charge.
There is no diode in particular you need to use, a standard 1A silicon diode gives about 0.6V voltage drop at this power level and are cheap, common as dirt. However for low voltage solar projects I recommend using a schottky diode because they tend to have only half the forward voltage drop. There is no particular one part # you need, there are many you could cannibalize out of some dead piece of consumer electronics you may have lying around, or any unregulated AC-DC wall wart typically is full bridge rectified, has 4 x silicon diodes in it.
Yes you could use one from an old PC. The power supply will usually have a few schottky diodes in it on the heatsink next to the wiring harness that exits the PSU. They are often double-diodes, the outer legs are anodes and the middle the cathode. Wire the solar cells to BOTH anodes to increase efficiency, and of course the positive battery output to the cathode.
You should be able to use the solar panels with no problems. The thing you need to watch for is how much voltage they put out. They could be only 3 volt cells charging up a single battery, and if you want to charge up two batteries at once you'll need more than one panel.
Just be sure you know how much voltage they put out, and that you know how you're wiring them together. Parallel or series (or some combination of the two). That kind of thing.
It would be cool to see what kind of voltage and amperage you could collect by hooking up a whole bunch of cells pulled from solar lights. How many of these things do you have available to you?
georogers2005@yahoo.com
(Sometimes paypal and my ordering system don't play nice. Sigh...)
I made basically the same set-up a few years ago, but as I was making mine for hiking I glued the solar cells to a piece of pvc siding (left over from my house) and then taped that to the inside of a ziplock bag.*
I then glued a piece of cloth to the back of the ziplock. The cloth is used to attach the bag with a pair of safety pins to another piece of cloth I sewed to the top of my pack.**
With the bag attached I can charge AA's while I'm hiking.
And I've kept the weight fairly low.***
*The siding is to protect the backs of the cells from the batteries bouncing around in the bag and lend some added strength (plus I didn't want to tape directly to the cells as I felt I might need to replace the bag later and tear off the tape).
**I tried using a Velcro attachment on a map bag years ago, but on a sunny day the glue backing on the Velcro melted and I lost the bag. Plus one side of the Velcro kept picking up crap, I got tired of cleaning it, and, so I moved to the safety pins.
***Some hikers worry about fractions of an ounce. Cutting the handles off tooth brushes and the like - I've never been that anal, but I still try to keep things fairly light.
Anyway, Good Job on the Instructable
Solar garden lights can be used as emergency battery rechargers, just remember to remove the batteries before dark when the lights come on.
AAA batteries are more in the 800-1000 mAH range, AA are in the 1700-2500 mAH range, never seen them as high as you stated.
AA and AAA NiMh batteries have rather high capacity these days.
http://en.wikipedia.org/wiki/AA_battery
If you're talking about cheap ones, yes, they do have low capacity. Ones I've pulled AAAs from solar garden lights have capacities as low as 800 mah. The big name AA commercial ones I've bought for home use tend to have around 3000 mah.
the 3000mah nimh you get from china are usually worse than nicad's (under 1000mah as low as 270 mah (no joke)
the best your going to get that REALLY ARE as rated is around 2400-2500 mah with 2700mah every now and then doable but finicky.
so 2500 is your top for reliable realistic cells.
But yeah, they're probably more like 2,500 mah, which isn't so bad.
where do you live? USA ? reputable store? ie real energizers?
I hope your right a truly reliable 3amp AA would be REALLY nice !!
Some other brand was 2,700 mah.
Try googling the brand of battery you have. Someone is bound to have that info on the net. If you are super worried about it then just use a single solar cell to charge up instead of two.
I recently pulled a AA NiCd battery out of a broken garden light and they were rated at only 800 mah. While that is more than enough to power a single LED for a night, it's rather low compared to most commercial.
I think 1000mah is possible for AA nicad but rare.
The batteries, wasn't say the don't exists, just never see them that high, not typical by any means. I got some 2700s last year, but there is no way, just don't last any longer.
How old is your Chocolate Lab? My Lab is about 3 1/2, still has some growing up to do, but is getting better behaved all the time. Fortunately, he lost interest in electronics last year, and I can leave parts and projects sitting out. This one only eat three remotes, and one extension cord. It was the components he kept getting into that real got me though, still finding them in the carpet occasionally.
I bought 50 AAA batteries off eBay for something like $25. They have a capacity of 1800 mah. I also have some AAs from the same company that are 3,000 mah. The Energizer AAs I have at home are 3,000 mah hour as well. They're all NiMh.
To be honest I'd love to use Some high powered capacitors for my projects, but they're just way too expensive. Especially with NiMh batteries being so cheap.
My lab is now nearly six years old. While she is no longer a puppy she is still a massive cuddle dog. She is also loving the massive snowfall here in Wisconsin. She just jumps around in it and loves to catch footballs while diving into snow banks.
the charging circuit won't even properly engage at lower than that on most phones.
YOU MIGHT be able to charge the cell DIRECTLY ie not through the phone.
so 8 of those cells would probably do it.
If anything you need a 5 volt power regulator thrown into the mix. Just to be safe. Look around the website and get some ideas on charging your phone through solar power.
Actually I'm building a solar powered USB charger right now. I'll be sticking it on my site for sale sometime this weekend. browndoggadgets.com if you're interested.
As soon as you start drawing current off the panel, the voltage will sag. Sophisticated solar controllers will manage this sag with MPPT (maximum power point tracking) - optimizing power by maximizing both voltage and current. That's probably why Kostya's phone didn't charge - it tried to pull more current than the panel could supply and the voltage dropped too far.
As with pretty much all modern mobile phones - the charger is built into the phone itself. The thing you plug in is just the power supply.
if you START with 5v your will end up around 4 volt after load.
Again, good luck, and keep experimenting!
kz1o
if it did "fire" it probable would not even be enough to pop the lid off so no worries.
People use Solar Lights outside in all sorts of weather, and when you get down to it, are not a whole lot more different than this project. Battery + Solar Panel + LED. Only with this we're not using an LED.
I guess if the plastic starts to melt then you'd probably want to be worried, but until then, you'd be ok.
I love this project, but I would recommend a Lock 'n Lock container made by Rubbermaid that has been spraypainted or covered with tape. They're the same thing but sturdier and only two bucks more expensive.
I once tried to do something similar with gutted solar garden lights. I made a charger that stuck to the window of my truck so I'd always have 2 fresh AA batteries. Didn't work out for some reason, but I might try again using this instructable as a reference.
Thanks!
That being said it does take a long time to charge up batteries. Even if you hit C/10 you'll need 15-20 hours of peak power to charge up fully. Not a problem if you're leaving it in the car full time.
Thanks for the rubbermaid advice. I'll try and find some for my next project. The dollar store is my cheap supply place.