DIY Solar Garden Light Hack - Solar Battery Charger 

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Wow, lots of questions. I wanted to go off the grid to show people they can do it and to see how it would feel if society broke down and I was on my own. I started in May 2012. It was a scary move at first, but its so awesome to have done it. I am single, this is my only place, and I rent the land I am. I have a day job, which pays the bills and keeps the car on the road. But ads from my website help too. I highly recommend everyone trying to become somewhat independent for the peace it gives

This video is responsible for the solar setup I have now. I saw it in 2012 and that peeked my interest

Thank you. Watch for the updates in the next couple weeks. I will add a voltage switch, maybe more solar cells and a USB connector to charge my cell phone. I am also looking into control circuitry to prevent over charging of the batteries if I forget to watch them.

For a small array like this one you could use a 1N4148. Larger ones where you have solar cells in series & parrallel to give the voltages and current needed to charge say a car battery you'll need something like a 1N4001. For kit with internal batteries like smartphones or 2way radios a proper fixed voltage regulator like a 7805 (5v/USB) or 7812 (12v) will be required instead of a diode and there is a 7818 so you could charge a laptop directly by solar.

It seems that it made more sense to face the wires from the solar cells toward the batteries, so the wires would reach. Is there any danger of over charging (or battery damage) if you leave the batteries in the charger too long? Thanks for the great ideas!

Thanks. You can actually use a USB cable to charge a normal cell phone. All you need to do is set up the solar cells to put out 5 volts. You can have various voltages from the same solar cells depending on how you hook them up.

Well done bro! Theres much can be done with these cheap lights. My mom lives in upstate ny and has a very dark stairway so i took one apart, extended the led connector and installed the light above her stairs while placing the solar panel in a fixed spot outside on the roof. Now she always has enough light to see the lights switch at night. I want to build this charger so thanks for the demo. God bless!

Yeah, its cool soldering off the grid. Actually everything is cool. I cut my own hair with a electric clippers and use an electric razor on my face every day. My panels are about 250 - 300 watts total. Nothing huge, but it does the job. I am comfortable. No fridge yet tho. My aunt was proudly showing me how she is using solar path lights for emergency night lighting in the house. They are very versatile.

I had to learn on my own by reading and taking things apart. Either way, it is good to know how things work. I have a lot of plans for these little lights in the near future. So many ideas, so little time...

Yes, if it has one. Most do not but only have a little transistor or small circuit in them. But if you have a diode in there, yes it will work fine.

You might want to attach a couple of mirrors that will bounce more light onto the solar cells. It shouldn't heat them up very much while getting more watts per solar cell. This would really only work when the sun is rising or setting and in the winter, but you can get some really cheap mirrors.

1n4001 or 1n4007 work fine. Basically any sort of rectifier diode will do. Its just a blocker to prevent the battery from discharging back through the solar cells.

Its AWESOME. It gives a sense of freedom, accomplishment and peace. And I never loose power.

It exists and its called a MPPT controller. Multi power point tracking solar charge controller. It used both a buck (reducing) and boost converter to get the best charging curve out of your solar panels. In full sun they put out about 18 volts and in low sun maybe 9 to 10 or so. The MPPT controller matches the battery voltage to the solar panel voltage, increasing the charge over all sunlight levels.

The price for 4 solar cells at a dollar each is $4. You can get diodes free anywhere, sometimes in the solar lamp. And its fun. And you cannot get cheap solar panels here. The shipping to bring one over here is more than the panel. Over here for a 5 watt panel plan to spend about $30 to $60.

Yes, you can connect them to get 14 volts to charge a battery. But the current is very low. Better to charge smaller batteries and use LED lighting to save energy. It would take months to charge up a car battery with these tiny solar cells. I got a bunch of dollar store LED flashlights I am converting to run off my solar charged batteries. They are very bright and run off AA or AAA batteries. String them together for best results. At least its free lighting for life.

I've got several of these solar lights under several inches of snow that I bought as Christmas decorations. Now I know what to do with them when they are uncovered after this spring. Thanks!! Ex Navy electronics technician looking for a new electronics re purposing project!!

If you left it for many days, yes it would. With smaller batteries you should pull them off the charger after a day. With larger capacity batteries it will take a few days to charge them.

Yes, AA and AAA batteries. All you need is the right socket. You could actually charge your cell phone with the right voltage and power connector on it. I will do an update on that soon. I am ordering some USB connectors from China.

Thank you for being thorough. When other videos just sort of show & tell the project after it's finished, you actually show HOW TO DO IT! Very nice work!

Yes, I will be making some upgrades for this soon. Keep watching. The batteries get warm when they are finished charging. Most charge controllers sense the temperature. This is such a low current tho that I do not think they would explode, but I would not leave them on for days after the are full

A Schottky diode would be best due to a lower voltage drop, but almost any diode (non zener) will work in this case because it is only blocking the voltage from flowing out of the batteries and into the solar cells when a cloud passes over.

That is cool. When I lived in Brooklyn, NY I used a 12 volt alarm system battery to power a battery operated 12 volt fluorescent lamp in the bathroom. The ones found in most hardware stores sold as closet lights. I had a shower room and a separate bathroom. Had a lamp in each. Saved some money on lighting that way.

These are usually a single transistor based boost converter. They step up the voltage from 1.2 volts to about 3.2 volts to run a white LED. You could use them for anything that runs in that voltage range and current. At some point tho, you will find its highest current limit and fry one. Keep track of what burns it out so you know your limits. They will charge anything within their voltage range as well. The 2.3 volt cells should happily accept the voltage, yes.

Any rectifier or schottky diode will do. A 1n4007 or 1n4001 will work. The Radio Shack part # is 276-1653 for a 25 pack.

I just fixed a bunch of lights that I use at camp. Several of them work, but the rechargeable AAA batteries are more expensive than a new light. So, the things are basically dead. BUT THIS is a great thing to do with them! All the parts work, but with the batteries costing more than $1 each, it seems better to just buy new lights and use the old lights to charge other batteries. AWESOME! The design would have to be different here due to the fact that it rains whenever it feels like here! If you have old lights and the solar panel is foggy, use 1000 and 2000 sand paper and toothpaste or head light defogger kit to make them work again! Cleaning the contacts and such, I just resurrected 10 lights last night. And have the parts to do this! Thanks

Hello friend. I had that very same idea. But at the time I didn't know that I needed a diode. I didn't even have a dial to begin with so that nothing went right. You were very informative I enjoyed your video very much. I hope you have a good day.

Yes if you leave them on too long. Just figure about 25 ma per solar cell and how many ma your battery needs to charge. A few hours give or take will not harm a thing due to the lower current

Each little panel usually produces around 20mA at best, so you are looking at 80mA (but I would say around 70mA on average). So if you have a single 1000mAh AA battery then it will take 14+ hours to charge. But it is interesting trying to re purpose these small panels, it's a fun thing to do. It could be handy for charging those 300mAh AA batteries in timely fashion.

A standard battery charger puts out about 80 to 120 mAh into the AA or AAA batteries for a slow charge. A fast charger will put out about what you have. I prefer the slow charge for longer battery life though. Please come over to thediyworld forum and let me know how it goes. Please upload some pics when done.

For larger batteries it takes about 2 full days of summer sun. In the winter about 3. But I use 2400 mah batteries. They are quite large.

In theory, yes. But it would take a lot of them to get any serious charging current. They are best used for smaller flashlight batteries.

Nice video tutorial on how-to. There is a voltage drop off with the diode attached but the diode is indeed necessary so the battery wont be discharged when there is no light. PRETTY COOL I SHOULD SAY.

Yes, you are correct. I wanted to quickly get the video done and show it working before it got dark out.

Sometimes Westinghouse brand has the AA or AAA. A lot of these are now coming out with the 2/3 AA. But you can use the solar cells from the dollar store path lights and get a battery socket at Radio Shack.

Yes, where you can buy dollar solar path lights to do these experiments. Its a great site.

I have wanted to do this for some time but I didnt think that for a dollar the solar cell would even work. I will try this myself!! Thanks

great idea.. I still say momentum / motor / magnet energy is still the number one immutable source if you got the leg power each day..

Looks good. This has serious potential. These little solar cells can charge an AA or AAA battery during the day, so 3 of them would put out enough for small devices. I am surprised tho that your devices take the 3.2 volts from the boost coverters on the little circuit boards. Most devices these days need 5 volts in.

Yes, actually the unmodified dollar store path light will charge batteries just about double the capacity of the puny ones they ship the lights with in a day with no problem. Some people add larger batteries to make them last longer each night.

Yes, sort of. They put out very little current. It would be a trickle charger to maintain its charge, rather than top off a battery. It may prevent a battery from discharging over time. I have been thinking about putting one together. You need 18 volts on the solar panel, no load. String them up in series to make 18 V. Then put groups in parallel to get more current.

To keep your solar cells working like new and charging paint them with clear nail polish they last longer great battery charger.

great people like you should post more tutorial that will surely benefit the mankind ..

I just watched a Discovery Channel documentary on a post apoc world. Was well done. Everyone will be a DIY-er very soon. I am trying to get the skills needed now so that I can survive later.

Yes, it is. As long as the battery has enough capacity to keep it running, no problem.

Believe it or not, with my cell phone. I can hook it to my laptop as a modem. I get pretty good reception, even in the mountains far away.

It is low current so a few hours are no problem. You have to do the math. If your battery is 500 mah and your charger is 50mah, then it takes 10 hours to charge a single battery in full sunlight. My batteries are about 2000 mah so it takes a couple days.

Wired in series you are increasing voltage. Wired in parallel to increase amps. Depending on your needs and the solar cells being used you may need a combination of the two to get decent charge!

I watched your video. Looks good. But, if you want to use it for gas output, then you will need to use a radiant energy generator, Bedini Motor. Please come over to thediyworld forum and I will help you on the way. A few of these in parallel could keep a car battery topped off, but not charge it on its own. They will also not generate enough hydroxy gas on their own. Use the Bedini motor, run it off the solar cells and then see serious gas produced.

Yes, just make sure you get the right voltage out and you have a solar USB charger. I plan to make one soon.

They should produce more than enough power. Make sure every cell in putting out power. Check each one individually. Then check your wires. Also tip the cells directly into the sun for best results. Straight up is not the optimum position for maximum charging. Maybe your batteries are weak as well. What is the max capacity of them? Get larger, 2,000 mAH batteries and see what results you get. Should be way better.

In between the panels and the batteries either on the positive or negative side. Just make sure you get the polarity of the diode right.

1N4001 or 1N4007 work fine. But a low power Schottkey is the best due to its lower voltage drop. Sorry dont know a number, but you can ask them.

I have questions I`m not into electronics I starting to learn after I`v seen your video , I believe in your case u have to take the batteries out when they are charged to 1,5 vold manually what happens if u live on all day the batteries will explode or inside the battery will be burned out after it has no usage of these batteries but my shop bought garden solar lights are on everyday n nothing happens to battery is it bcoz they might have electronic cut offs after they r full charged?

Yes, that is a relatively untouched area. They are very fine boost converters, but noone really knows what to do with them. I sadly have no 3 volt devices, so I cannot use them. But they may be good for running some LED flashlights. You could even theoretically string a bunch of the circuits up to run higher powered LED bulbs, such as a 1 W LED. Now that would be an accomplishment.

Yes, but the commercial chargers do measure the temperature. As the batteries charge up, they get warm. I will be making the circuits later and showing how.

There is normally only a transistor on the board, which acts like a diode sort of. Place a diode anywhere between the plus on the battery and the plus on the solar cell output. I can fully help you if you come over to thediyworld forum and post a photo. I can then see what parts are on your board and help you get it going.

Yes, the Dollar Tree. They come and go. You need to watch for them because they sell out fast. I just got some Christmas ones at Walmart on clearance for 60 cents each. I look around. You can also find them online at the dollar tree website. Family Dollar also carries them on holidays like the 4th and Christmas. After the holiday, I grab them all up on clearance.

Various dollar stores have them at different times. I go back once a week to each chain to see what I can hack for me newest projects. Keep checking, eventually you will hit the jackpot

So how long did it take to get those batteries fully charged? We need stats...

I've been watching your videos for a few days now. I decided to go to the beginning and start watching them from the start. I really like this project, I've been thinking of doing something similar myself for a while. Glad to see you're back from Australia, I'm looking forward to the projects you mentioned you have in store for this year. All my best, Colin

The capacity of the panel should be matched to the batteries. Sounds like the solar panel is a 6 volt panel and maybe puts out half an amp in a day. Not very large. You would need two in series to make 12 volts and only get half an amp of solar power per day. You need a larger panel for larger batteries.

That is fine. You can use the same diode with multiple cells.

No problem. Please let me know how it goes.

All Thumbs Up Every Time ! # 5.6K + The circuit board is a comparator board.

Thank you for the feedback. Happy to help.

I have a general idea of the solar cells capacities because of the original batteries that came with them. Mine, for example, were 120 mAH batteries. That gives me about 120 mAH per day of charge per cell. 5 cells gives me about 600 mAH per day of charge. You can also just measure them from time to time. A rechargeable nicad is about 1.2 volts charged. When I get the to about 1.3 then I pull them off the charger.

This is very informative. I want to begin a small solar project and you have taught me a lot. Thank you!

use a cig lighter to strip the wires,wont damge the wires that way.

I got a 100W solar panel for 103$ great deal from amazon And I can charge a 12v battery and running a table fan and a desk fan at full power 30 watts + 20 watts directly from the sun! I can even run a small laptop from it!!! I power a 12v DC to 110-125v AC inverter rated 400 watts and the battery is 5 amphours (which should definitely be increased to like 35AH) Works great!

FYI to anyone who may copy this... If you build a charger without over and under charge protection you run a very high risk of damaging your batteries, possibly catastrophically. You could very easily start a fire or cause injury. The circuit this guy removed had those protection schemes in it.

Yes, you would need 8 or even better, 10 of the cells. With 10 you can get charging with a bit of overcast as well. Your cell phone and some other devices have a built in charge limiter in the device. Otherwise, the circuitry gets a bit complicated with the need for a voltage monitor on the output of the solar panels which can shut off the output to the device when the voltage reaches a certain level.

You only need to block the power from flowing on one side. It has to flow through the circuit and back again. Blocking it on one side does the job. One diode. The original circuit regulates the on and off based on if the sun is shining or not. This is a battery charger though. No LEDs in the system. Just the solar cells and your batteries to be charged.

I have rechargeables that I had for about 7 years now and still going strong. A few have failed along the way, but most are good. Get the good quality stuff and they last.

This video was worth a subscription. I’m a fifth grade teacher and we make circuits. I wanted to learn how to teach them how to do electrical circuits with solar panels, but I’ve never done one before . The connecting of wires is what’s confusing in the video, but I will keep watching this to see if I get it.

VERY GOOD IDEA. Some one ask y not buy a solar pannel ..well in my small town of 500 people we have 1 dollar store and its about 80 mile to Evansville to even find a store that sell big high end solar pannel ..this is a cheap why to get a few amp from very little money

It would actually be easier to use a couple solar cells to charge AA batteries and use that to charge your phone. I have an adapter that uses AA batteries and plugs into a cell phone. Otherwise you need to string up a lot of these cells to get enough power for your phone to recognize it. They produce about 25 ma each at about 2 volts with no load.

You can post images on the forum, no problem. Dont worry about your writing.

Yes. Its so cool when things come together.

Those lights are strong anyway. And pretty efficient. I use them a lot myself.

I think I will get a few and tear them apart to see what makes them work. See if anything is useful in them.

The reason why he cut out the original circuit board, is because those circuit boards in the Garden light also control when the LED lights Turn On or Off, depending on the Sun. When Sun is up, the voltage is high, and LED light turn off. When the Sun is down, voltage coming into Solar Panel is gone, and LED lights Turn On , automatically. So, the best thing is to cut off those circuit boards and replace them with Zener Diodes for Voltage regulators. Search Zener Diodes, 5v or 6v. The cut off power when Battery is charged to a certain voltage.

Now how to make it waterproof 😁. Very informative, thanks.

1N4007 or 1N4004 are both fine. Just about any blocking diode will do.

Funny, stumbled on this after making my own similar project. I joined 6 lengths of Harbor Freight solar rope lights, and make a 6 piece solar panel with the cells taken from each rope light, that now charges six 1900mah AA Eneloop cells in parallel. The original cells were as yours, 600mah, but were AA, not AAA. The low charge rate coming out of these solar cells should help the batteries last a very long time.

They should have some diodes or they should be shut down. Radio shack is supposed to have a set of drawers with small electronics parts in them. There should be a drawer dedicated to diodes. Anyway, you can get rectifier diodes off ebay as well for pennies each. Get 1n4007 or 1n4004, should be fine.

Nice, I need to get more. I use them for a lot of projects. More ideas on the way soon.

TO:Michael FTW, Batteries for cell phones and other USB devices are Li-ion batteries which are VERY sensitive to over-voltage charging. They Will be damaged and have been known to burst. If you/one adds a 5.6 volt zener diode to the circuit it will limit voltage to 5.6 volts. Diodes 1N752 or 1N5232 would work great. They are $0.10 to $0.20 if you buy ten on EBay and there is not S&H. Also available at Radio Shack.

If I remember correctly from my electronics classes, when you wire in parallel, the voltage is the same and the current in stacked, when you wire in series, the current is the same and the voltage is stacked or added together.

It depends on your circuit. Most of these are designed to put out about 3.2 volts to the LED. The battery is 1.5 volts. How it does this is to make a sort of DC to DC voltage step up converter from 1.5 volts to 3.2 volts to drive an LED. So, most of these need to have the original circuit removed first. The circuit is normally a transistor, so no diode is needed. Hope this helps some.

Happy to help.

Thanks for your response. It would be very interesting to know your story and how did you turn to off the grid. How many years since you moved there? Is your only house? Do you have family? How do you cope with other costs, do you have a regular job as well? Do you recommend this lifestyle and other questions like this :))

I have a few wall solar lights, struggling charging, no sun in Ireland, so I replaced all the recharging batteries with regular batteries. Now i have light in the garden all night, in day time the lights are off due to the integrated twilight sensor. The overcharging protection is working, it does not charge because the voltage is steady to 1.5v, no danger to explode, even if does, I do not care.

Sounds like fun. I love electronics and making stuff work.

i dont know all this fancy voltage talk i know it comes natural to you. But i tried this and it works. just takes like 10 hours since you got 6-7 AAAs you can leave it outside all day and night just disconnect a wire

They are designed to use 1.2 volts in and put about 3.2 volts out. Probably not much current output, but it would be interesting to find out what their limits are. I have a bunch of them laying around after hacking these solar lamps.

Yes, more panels = faster charging. If you want to charge a 12 volt battery, you need 14.5 volts to charge it.

Yes, it would be way too many amps. Your solar cells put out about 3.6 amps? AA batteries can only handle about 80 to 120 milliamps max charging current. I have often tried to think of ways to use my extra 0.5 volt 3.6 amp solar cells. I might end up using them with a boost converter one day just for fun.

Normally in the garden section. But I never saw them that cheap. Normally about a dollar though.