Solar powered meteor light project.

You can now buy me cake and things to take apart at:- / bigclive
Finally I get round to combining a couple of recent teardowns into something new. This is a project to make the common ebay meteor lights solar powered, using a common ebay solar panel, an old or generic phone battery (lithium cell) and a few components.
The circuit will also run strings of parallel LEDs or even a single high power LED.
It's been mentioned that the reverse biased solar panel will leak some current as it is connected between the positive rail and base of the transistor. I'm not sure what current will flow when a 10 or 12 cell array has a reverse voltage of 4.2v - 0.6v = 3.6V across it. A test with 5V showed a current of 300uA which would flow into the transistor base. Is a slight reverse current likely to damage the array? I've never really considered anything other than battery discharge through a reverse biased solar cell. Can such a low reverse bias voltage damage the array of cells?
Comments and thoughts on that are welcome.
You'll need:-
A solar panel capable of putting out 5 or 6V at around 100mA or more. (But not too high a current as it will be charging the cell directly.) If you live somewhere with dull winters a higher current (larger area) solar panel will be a good idea.
A typical cellphone battery (lithium) with built-in protection. Many of the generic Nokia type are commonly available on ebay.
A set of typical meteor lights that usually come with a slightly dodgy power supply.
A transistor, either a BC547, 2N3904 or anything general purpose.
A rectifier diode like a 1N4001 to 1N4007 (all 1A just different voltage ratings.)
A 10 ohm resistor to limit the maximum current through the transistor.
A 10K resistor (10,000 ohms) to limit current to the transistors base.
And a little bit of solder, wire and time.
Here's the Jaycar (Australia) link to their resistor dial.
www.jaycar.com....
And another Australian supplier:-
www.wiltronics....
An American supplier of a different type of resistor substitution box in kit form:-
www.parts-expre...

[@miniwarrior7]

I love these rambly style videos where you're learning as you go!

[@Elfnetdesigns]

Good call on the negative rail diode, that is the same exact design I came up with using a 4.7K resistor to add extra battery life, and a 2N3904 since it is made for switching purposes. The 2N2222A is a GP NPN that will work just fine as well if you cannot find a 3904. What I did with the battery was salvage the actual phones battery holder and use that with the solar panel hot snotted onto it, This way I did not have to apply heat to the battery itself. Ok update, New weekend project on my end too! lol I got the t5 led lamp in today and I got the RGB LED tape in 3 days ago, so let the HAX begin!

[@marcvisconte9487]

Always enjoy BigClive's videos. Found this and didn't realize it was 2 y.o. I love stuff like this, and makes me remember why I saved all of those phone batteries!

[@Jonnyb1925]

I laughed out loud at the "Yay!" when the lights worked as designed.

[@killer1479]

18hours on a single charge ? and powers 32 meteors ? YOU my friend have found a way to kill the market with this!

[@BigClive]

+killer1479 It's not running them at high intensity. But it's still a nice effect.

[@Autunite]

+bigclivedotcom Still! It's impressive. You should start making energy efficient lights and sell them on eBay. I would buy every single one of them.

[@BigClive]

+Delightful Hardware I think that's definitely a job for China.

[@killer1479]

bigclivedotcom but still, if you have these made in china and sold them yourself, i would sure as hell buy some :D

[@killer1479]

Delightful Hardware agreed!

[@JimFortune]

Stop apologizing for rambling. It's half the fun of your videos.

[@marceldroto9239]

And we can always turn it to 2x playback.

[@icarus901]

awesome, thanks for reminding us about BEAM..I haven't thought of tilden et al in oy, nearly 12-15 years? I'm sure I have some funky free-form circuits hiding in boxes dating back to 1999 or so. Remember photovores and the little walkers?

[@stevenA44]

I bought a set of these for $5 at a pallet store and they came connected to a solar cell with a battery. Not sure what kind of battery but after leaving the solar cell in the sun all day, the lights ran a very long time. Somewhere around 6-8 hours. They're really cool lights. I have an affection for LED lights. LOL You wouldn't believe how many I have! I burnt the piss out of two fingers the other day when the soldering iron slipped! I grabbed a cube of ice really fast. Didn't hurt much after that and didn't blister either.

[@youtubkeeper]

I'm inspired to make some of my own as I've got a bunch of lithium phone batteries and solar panels lying around. Thanks for all the videos!

[@gigabytex64]

I enjoyed every second of that, as a relatively newbi these type of videos are a goldmine of info so thanks

[@ColmJones]

Thanks for the info in the video Clive, I'm going to use it for a project to illuminate a small outdoor wall plaque. Keep making the great content 👍

[@nuckelheddjones6502]

I love your videos man. they are like talking with a friend. Love the spelling mistake and your reaction. Gave me a good little giggle.

[@whitefields5595]

Clive, Thanks for this. I added it to your Joule Thief I built yesterday. Using the PV panel as a light detector and switching on the negative rail is so simple, effective and minimal parts. It eliminates the use of the photoresistor/transistor used by many. OK we may have to tune the transistor base current, but that is a small price to pay. Please keep these videos coming as they show that we should never forget to understand and then apply the basics that some us us forgot a long time ago!

[@johnbrandolini2915]

Clive, I would isolate the LED drive circuit from the solar panel by using a 4N25 optoisolator. Here in the states they go for about 25 cents. The device input to output isolation is 5000 Vrms. Along with the opto you would need one extra resistor in the base circuit of your transistor and a 470 ohm resistor in the drive circuit of the opto.. I calculate the bias values at 3k Vcc to base and 820 ohms base to ground. That would drive the transistor into saturation. Connect the output of the opto across the 820 ohm resistor. When the solar panel is lit it will short the 820 ohm resistor putting the transistor in cutoff. Those resistor values should ensure that the LEDs will remain lit about up to where the battery voltage drops to 3v. I use 6N137 since that's what I have in my "junk box". Also for current switching I usually use a TIP31C NPN motor control transistor since it will handle 3 amps continuous @ 100v. They're about 39 cents each; cheaper in lots of 10. Probably overkill for your app. I use them to drive long strings of white LEDs for back up lighting since they draw about 1.2 amps at full intensity.

[@derrickblackburn2062]

Its remarkable how much energy is in a these lipos. I was given a new bluetooth DOA speaker and swapped the dead chinese 700ma battery with a 1350mh samsung. Had to melt a few things with the iron to fit it together but its runtime is like two days at lower volumes.

[@maxximumb]

Brilliant video, I'd like to see more experiment type videos. I learnt quite a lot watching this. Thanks.

[@JohnOHalloran]

It's one thing to do all those dinky projects to get my skills back, but I get bored with just blinky leds. This is a project with a useful endpoint and looks very easy. Thanks.

[@thany3]

Pretty cool! Using a solar panel to charge AND effectively as a light sensor.

[@Ezloopz]

Pro-tip @ 12:29 .. never thought of that, cheers big man

[@Yotanido]

I had no idea what you were on about in the beginning at first. The schematic made no sense whatsoever to me. Then I saw the circuit in action and it all makes sense now :D

[@LancerSolurus]

Have you tried using a high value cap instead of a resistor across the solar panel? In a circuit I use for a night light it delays the switch on time by storing some of the solar power, thereby tricking the light circuit into thinking there is sufficient light. By the time the light switches on it is completely dark...

[@mn_ambrose6488]

A nice little project. Since mine is targeted for indoors, I added a small switch to the output, so that I can turn the load off when I don't want it running. Otherwise, works well. Thanks

[@willyhoogs]

Wow! So cool. I cheered for you when the lights turned on!

[@edwinlipton]

Your the MAN! GREAT VID CLYDE.

[@THEDRAGONBOOSTER8]

Very clever,Big Clive

[@smallenginedude71]

yes. as you said about that resistor substitute you can certainly get that here in Australia in jaycar. probably easy to find on ebay also.

[@samueljames9342]

Great video, my lack of a diode explains why my rechargeable led flashlight discharges prematurely. I'll add the diode today and should be good to go.

[@craftsman123456]

Got the lights and Solar panels in the mail over the weekend. Put it all together tonight. Seems to be working fine. I still need to test it on daylight and see how well it charges.

[@craftsman123456]

Been running for 9 days straight on just the daytime charging.

[@grahamrdyer6322]

That's the problem I had making "Auto ON/OFF lights" they came on to early, so I built a super simple circuit using a Photo transistor and a PNP Darlington transistor, oh and one Resistor. but yours seems to be very good and 18 hours fully charged WOW, Mine runs two 1/2 watt LED's for the chickens, now the only thing to hope for is a bit of sun now and again.

[@southernnutcase]

you know for nerds like me (and i'm sure others) you should put together little "kits" of like the bulbs and boards that we could get from you and assemble while we watch the videos over! .. that'd be sweet! tho here in america we would use all different power factors, and connector types hmm .. didn't think this comment out lol

[@twocvbloke]

That's a pretty neat setup there, I have a 6v panel somewhere (came off a cheap "generic" solar fountain that broke after three days) that's begging for something to be done with it, may have to find it and figure something out with it... :D

[@metricstormtrooper]

Great stuff Mr Clive, greetings from Tasmania both entertaining and informative!

[@digitalmasters8253]

them lights are wicked, great build clive.

[@tiikoni8742]

These are great videos! I have sudden urge to order bunch of components from ebay and start building things :-)

[@musicinspire1745]

I think you're right about the transistor lead identifiers. The British drive on the wrong side of the road, so it only makes sense that their transistors are opposite (wrong) as well. (snicker, snort)

[@edwinlipton]

Maybe we drive on the wrong side of the road and they have the drivers seat and steering wheel on the;; RIGHT SIDE of the car, either way a slight head on collision with on coming traffic is almost certain death. Think about it,,, you'll find were both a mixed bag of nutts.

[@musicinspire1745]

@@edwinlipton Humor must not be your strong suit.

[@Alexwilson225playsMC]

Awesome Video! I am enjoying your channel so far. Keep up the good work!

[@mozwell69]

Thank you Clive your a star

[@TheNevermind007]

Hi mate, this is brilliant! Could you use a few of these to power a shed light with different LEDs?

[@StreuB1]

This was a great video. Simple enough to where I (a complete moron with transistorized circuitry) could make sense of it. Thanks Clive!!! :-D

[@danielmf1839]

Very good and simple idea, thanks!

[@fpvrcstuff]

Great little project Clive ..........Love it !Cheers

[@TheMahtimursu]

Hi Clive. Thanks for your great channel. This circuit is nice and simple but it switches on very early. Is there any simple way to change that? Does transistor type have an effect here? Resistor value does not seem to effect much. QX5252F chip is perfect for this purpose, but it only works with low voltage NiMh -batteries. I'm currently trying to find a similar solution for LiPo and LiFePO4 batteries.

[@RoelNicky]

nice little project, just ordered everything from aliexpress ;-)

[@Wesshaw1996]

thanks for the build video

[@fromfin90]

i should salvage something and build this for the fun >_> looks so easy! and that would hang on my balcony, charge on the day. Maybe add a charging port XD Finland is not the brightest place in winter :p

[@FireSwordl]

Hi Big Clive. Can you show us a video - how built in battery protection works?

[@Novalight2550]

Very cool. Do keep us updated on how long they last at night.

[@BigClive]

+Nova Light So far the full charge test lasted a very impressive 18 hours. And as predicted it was the lower voltage LED colours (red and yellow) that pulld that down a bit. With the amount of sunshine we get in the UK I'm expecting a run time of at least 5 seconds.

[@Crispy_Bee]

+bigclivedotcom then maybe you should use all solar cells next time ;)

[@Novalight2550]

Wow.

[@timrattenbury5321]

I am from Australia and I have seen them at jcar

[@mikedrop4421]

Wizard. Absolute wizard.

[@JerryEricsson]

Greetings from the wet sands of Arizona USA, a state we fled to when the snows of November came to the Dakota's. I have been soldering onto those little gold tabs on used cell phone and pDA batteries for quite some time now and never ran into any problems doing so. I suppose if a person used to much heat some damage could ensue but those tabs seem to love solder. I have had some trouble with the wife, however, when she learned that i used her spare phone battery to power a ghost detector for my niece's paranormal group she was quite upset. She got over it, however when I switched my iphone over to her phone number and gave it to her. Now I am using a crappy Android, and she is overjoyed with her new toy. I do miss my iphone now but my niece loves her little ghost detector so I guess it was almost worth the trouble. I used one of those little batteries in a cheap china dash cam that I wanted for our trip south.

[@deslomeslager]

Recently I made the same circuit. But. Not every solar panel is suited. I found out that the monochrome solar panels don't work, and the black with blue ones do (like the one you did not use, that 6V/1Watt panel). So the monochrome panels leak (much) less current I guess.

[@wanjockey]

great video thanks for sharing.

[@ImigrentfromMars]

I have this one saved ..... I wonder can you do a video on this but scaled up? I have a 12 volt car battery ''deep cell slow drain'' also 3x 12 volt 20 watt solar panels and led head lights that do not fit my truck . I want to make flood lights to shine into my house windows when it start's getting dark at 4 pm so it looks like it's still sunny out lol I have solar lights around my windows in the house but there not bright enough they work good for getting up in the night but i want real light from 4 to 7. im hooked up to 12 volts using led strip lights in my house for when the power goes out but id like to hook up some that come on by them selves. I was going to order some street lights after watching another video you did but if i can do it my self with the supplys i have then why not. I have more led cob 12 volt 70 watt on the way so ill be using them for this project. I seen you have some as well and thats why i ordered them i think they will work good for what i need.

[@himmune3784]

hey big clive im from aus and have a local jcar if you would like me to see if they still sell the variable resistors

[@cmj20002]

Same as for the 2n2222 E,B,C and super common.

[@gateway8833]

Anyone can make those complicated over done circuits, it takes talent to do all this with just a few components.

[@TheKutia]

This is awesome!

[@coloradostrong]

Mr. Big Clive, 2 quick questions on the lights: technically you can run just 1 tube at a lower voltage than the 7 volts that most of these are supplied with, yes? and, I have a string of 16 tubes and 10 tubes. They each have a 7 volt transformer. The 10 tubes are extremely bright compared to the 16 tubes. When I add the 10 tubes to the 16 tubes they become "normal" brightness. Can a resistor be added at the end of the 10 tube set to reduce the voltage to around 6 volts? The voltage at the end of the 10 tube string is around 7.6 volts, whereas the voltage at the end of the 16 tubes is about 6 volts.

[@BigClive]

They will often work on a USB power supply.

[@Neffers_UK]

Brilliant.

[@cmj20002]

Did you think of trying the QX5252F solar LED driver chip. It does the job that you are looking for it to do, but I am not sure what cell it uses. Mainly NiMH I believe. They go to battery when the sun goes down and when the sun shines it charges the battery. They work really well. They need a modest inductor as well.

[@Slot1Gamer]

link to the resistor wheel: www.jaycar.com.au/Passive-Components/Resistors/Other-Resistors/Resistance-Wheel/p/RR0700

[@stonent]

+Slot1Gamer 30 Australian Pesos!? Man, that was a bit more than I was expecting.

[@stonent]

+stonent I found this out of the US. Not as many choices and not as compact, but about half the price. www.parts-express.com/elenco-resistor-substitution-box-kit--320-076 EDIT: Apparently there is a US Jaycar site, and it's $18 or so there.

[@ethanpoole3443]

Another Elenco alternative that is very flexible, 1W@1% resistors with 1-Ohm increments possible. I have this model and only two values were slightly out of tolerance (1.1%) on the megohms side, all others were pretty much within 0.5%. Just be aware that turning *everything* to Off is essentially 0 Ohms resistance (for applications where such matters). Very easy to repair if you ever damage a resistor. www.amazon.com/Elenco-Watt-Resistor-Substitution-Box/dp/B0002KX76M

[@DarcyFerrier]

+stonent lmao, Australian dollars.

[@stonent]

It was a reference to AvE's channel where he refers to Canadian dollars as Canadian Pesos.

[@arthurschroeder3003]

Love Your Vids keep it up.

[@craignehring]

Brilliant

[@tennicktenstyl]

note: if you are salvaging transostors from electronics you may find some japanese ones, they have left to right emmiter collector base. Kinda weird, I think it may be useful if you really want a clean looking circuit, it gives you more options when it comes to layout of components but other than that it only requires you to check whenever you take an salvaged resistor.

[@gregmilstead1369]

Sir bidclive could you show us how to build a ac dc test light with two leds that would light one led when put across dc and two leds will light when put across ac ty your videos help me a lot

[@BMcKenna]

Great vid love the idea :D

[@miniwarrior7]

Simple solution to the poor light sensing: Just put the panel in a shaded area, so basically anywhere in the uk

[@recklessroges]

Other way round. Put it near enough to an outdoor light to stop the transistor being triggered too early.

[@JimFortune]

When "ballparking" resistor values, why not use a trim pot instead of fixed resistors?

[@Anvilshock]

Because trim pots don't come with readable dials, wires, clips, nice hand-friendly housings, and most important: They don't come with decent subdivision across 5-6 orders of magnitude in a single package.

[@PlasmaHH]

Since you have so many of them... I am thinking of hacking some, and was wondering if the pcb material inside there is stiff or flexible like on many LED strips

[@coloradostrong]

I just received some of these lights from Amazon for free, and I was wondering why they use 7 volts. Most of these lights have the ability to connect up to 4 strands together.

[@BigClive]

The voltage is a vague value that varies from about 5V. It just has to be above the LED forward voltage.

[@arivefabian]

i have made the same circuit before and i found out that it work better with a 22k resistor , if u have time u can try it and see but i havent done it with so many LEDs i was wandering how long is gona last with that cell batt, even i use that same circuit but instead placing a relay con the LEDs terminals and then driving a 12 led system , btw i like ur lights videos a lot .can u make a circuit like that with the same functionality but with a 12v sourse so i dont need to use a relay? because the relay runs the battery out really fast. thkz , very nice video

[@placidcasual989]

Hi there, I watched you videos for a while now and this is the 1st thing of yours I'm going to make. I'm going to put this on the front of the house north facing about 2 or three stings of the meteor lights . I live in west lothian will this set up be fine for the amount of light I get? Thanks

[@AureliusR]

Also, I've been trying to put this warning on any video which directly compares BC547, 2N2222, and 2N3904 as direct substitutes. While you could replace a Bc547 with either of the other two, you should NOT go the other way in many projects. The current rating is vastly different, from ~100mA on the 547 to ~800-1000mA on the 2N2222! Just keep this in mind when using whatever you have on hand. Be careful to double-check the current rating, and always look at the hFE of transistors to see what kind of current you'll need to get the same effect.

[@yorickhunt3371]

A quote from one of Peter Sellers's lesser-known masterpieces, The Fiendish Plot of Dr. Fu Manchu, always comes to mind when someone refers to British weather... "Is the weather always this piss-poor in England?" "Why no, we have several bright days every year!" WRT resistance wheels... For little more than double the price of what Wiltronics is asking (and significantly less than double Jaycar's price), you can get a full decade box from China; www.aliexpress.com/item/-/32309806626.html - not exactly a portable toolkit item, but far more versatile if you're tethered to the bench anyway.

[@fabts4]

I don't get why the value of the 10k resistor should have such an importance in regards to the sensitivity. (I don't think it shouldn't, I just don't get it)

[@gregorythomas333]

I might have missed it but why did you not use a LDR (or a CdS cell as we call them) to be the light switch?

[@LunaticCharade]

because ge already has the solar panel sensing the light, keeping the circuit simpler

[@rhouse6898]

Is it possible to make an AC DC LED light that well run on AC or DC... because the DC light fixtures take are the same as an AC light fixture

[@hmax1591]

How long does it take that solar panel to charge the battery? Can it supply 500 ma at least?

[@webchimp]

wiltronics. I get annoyed by sites that won't tell you the total of what you are looking at until after you have given them your info/registered. It's price - GST (ouside Aus) + p&p, and I'm not giving them my name and address/email etc to find out. ###edit### I mashed some random crap into the fields to get through and they won't tell me the postage until after I bought the item because I'm outside Aus.

[@blondieman63]

Hi Clive, just made this, but the meteor lights i have are smd on a strip, only light red on the top of the strip , can i upgrade this to x4 AA 1.2v , these light the lights can i use the same circuit? Thank you.

[@BigClive]

Most of these strips will run at around 5V so just 3 cells may be enough.

[@kingmuppet7023]

Here is the resistor wheel link jaycar.com.au/Passive-Components/Resistors/Other-Resistors/Resistance-Wheel/p/RR0700

[@BigClive]

+Neal Jorgensen Thanks. I've added a link to the bottom of the description.

[@BigClive]

+Walter Boxhead It might be worth opening it and checking the little ballbearings that click into the PCB holes are lubricated properly. Noting that they may try and escape when you open it, so do so in an area that will make them easy to find. Mine is ancient too. It's a surprise that they're still sold.

[@BigClive]

+Walter Boxhead I suppose that technically speaking the wiping action makes them self cleaning. And even with modest use it's not going to clock up a high mileage on the contacts.

[@BigClive]

+Markus Bates Yeah, I've been looking at the other options, but the rotary one with standard values is the easiest and quickest to use. I wonder if they are even still made any more, or if the ones from Jaycar are just remaining stock.

[@MrGigglez2010]

I have a pair of Elenco resistance/capacitance substitution kit boxes Cool!

[@rubber20021]

regenerating idea maybe?

[@Totogita]

nice video how can one tells if a battery is protected from overcharging? should we assume that all cell phone batteries are protected?

[@BigClive]

Most traditional phone batteries have a layer of protection. The only sure way to know is to test them.

[@Totogita]

Thanks!

[@RobertShippey]

The most common Nokia battery on eBay seems to be the BL 5C which doesn’t have protection. Be careful, assume it doesn’t unless you *know* otherwise.

[@Roy_Tellason]

@@BigClive How do you test for that? I have a couple of older cell phone batteries around here and would like to use them if that protection is in there...

[@desmondandson4223]

im going to sound very thick but im new to this is there much difference in the transistors i have a whole bunch but not the one you mentioned

[@BigClive]

There are a lot of different types of transistors. The type you are looking for should be a general purpose low power NPN transistor.

[@desmondandson4223]

thank you :)

[@paularyan4482]

Hi do you have a link for the transistor please as i looked on rapid electronics and there are 5 different ones also eBay has lots of different ones. I'm very new to this and i love recreating your experiments thanks..

[@BigClive]

Any of the brands of BC547 will do. It's a very common transistor made by many manufacturers. Here's a link to a typical one. www.rapidonline.com/trusemi-bc547b-transistor-npn-to92-50v-81-0468

[@paularyan4482]

Thank you very much keep up the great vids.

[@76coxs]

how many hours that battery runs if you have a 4 sets of led lights

[@bestamerica]

' can this LED lite use a pack of four AA batterys and button switch as off-on

[@BigClive]

It could possibly run directly from a battery pack or USB power supply.

[@artchie81]

how many hours of battery or how many hours

[@derekthomson3025]

Noob question: Does this work just as well for other type of rechargeable batteries? i.e NiMH

[@BigClive]

Yes it should. The Nickel Metal Hydride batteries will handle continuous charging at around 100mA. You could use either three in series for 3.6V (4.5V fully charged).

[@derekthomson3025]

Thanks Clive. This is just perfect for the small project I've been stuck with?

[@AureliusR]

Even though the battery has overdischarge and overcharge protection, don't you still need proper LiPo charge circuitry? I thought hooking it directly to a solar panel was a recipe for disaster, or at least greatly shortened LiPo life...?

[@AureliusR]

+Aurelius R Or, is a solar panel more of a current source than a voltage source? Will it just clamp to the LiPo voltage and current limit that way?

[@BigClive]

+Aurelius R The solar panel acts as a current limited source. The LiPo has an internal protection circuit that would disconnect it if it was fully charged, and the solar panel would then float up to its maximum voltage of around 6V.

[@hanelyp1]

+bigclivedotcom , the circuit you designed would be a disaster if the battery didn't have a protective circuit built in, on both overcharge and discharge.

[@BigClive]

+hanelyp1 Yes it would, which is why I stated that the cell has to have the protection circuit.

[@DavideFilippone]

Are you the Bob Ross of electronics? :D

[@jlshafer777]

What enclosure was used for the project? I'm wondering how he kept the water out of it over time.

[@BigClive]

I used this indoors. It's running right now.

[@jlshafer777]

bigclivedotcom any advice on what to use for an outdoor setup? Might make a good video.

[@imonaflatearthur2917]

Isn't a collector , base, emitter -----emitter ,base, collector, transistor, the same thing merely flipped over ? Or was that just a poke at the yanks?Hmmnn.....

[@RFC3514]

+Monty G - He was drawing it with the flat side up.

[@Cyparagon]

Big problem here. You're forgetting the base-emitter junction is one diode drop. That allows a potentially large current to discharge from the lipo, through the solar cell, and through the base-emitter junction. That is why you are still getting the lights to activate even with no base resistor. The solar cell is acting as the base resistor.

[@BigClive]

+Cyparagon Keeping in mind there are 10 cells in series, I'm not sure how much current is likely to leak at 4V.

[@BigClive]

+Cyparagon I've just tested it with my bench supply and all the panels leaked roughly 300uA, so that would definitely have turned on the transistor. The question is... Are the cells likely to break down over time and pass more leakage current. I'm not sure about that.

[@Cyparagon]

+bigclivedotcom Thanks for the data. I haven't worked with solar panels often, but I've poked around google just now. It looks to be safe, and total energy losses are actually higher when using a blocking diode, except in high voltage systems. So not a big problem after all, but something to be aware of. Revised concern: The blocking diode isn't blocking at all, and is actually eating power when charging.

[@mrlazda]

+bigclivedotcom You can easily fix it, just put diode between base of transistor and negative of solar panel to block current coming thru solar panel. That way you will help to fix problem of controlling on point and you not need to care if leakage current increases with aging of solar panel edit: i think you can't control on point with changing value of resistor, it will turn on immediately when voltage of solar panel is lower then voltage of battery

[@mrlazda]

+Cyparagon Blocking diode is blocking current from battery to close circuit directly, now circuit is closed thru base of transistor.

[@the23er]

Nice circuit, looking for that for a while. I am quite conservative when it comes to using LiPo. How can i check "from the outside" if the protective PCB is present? And what Voltages will these protections usually take? I dont want to have them explode...

[@MyBigThing2010]

In the future, can you show the camera a close up of the orientation of the component before soldering it? it would help us idiots that are trying like hell to get a grasp on things out a whole lot. I'm still not getting why you used a couple things where you did n what they do...like resistor vs diode...n where the values came from. thanks ohmie!

[@hansparam]

I tried this circuit with success and using 18650 li ion battery but there was aprox one volt drop from the battery to the LED light without current limiting resistor. Is there any way to get same voltage for light as the battery voltage?

[@BigClive]

The transistor would limit the current. You could use a MOSFET, but there MUST be current limiting for the LED.

[@rival_son]

@@BigClive I've been asked to try to fix a newer (slightly better) set of lights like this. I've identified the transformer board is faulty.. would you like a look at a TINY 8V board?

[@miteshdhanani]

How time hrs will it work

[@Derotron]

Could I just switch the Meteor lights for 5 White 5mm LEDs while mentaining the circuit you used?

[@BigClive]

You would need to use suitable resistors in series with the LEDs to limit the current through them.

[@Derotron]

bigclivedotcom Would around 200 ohm bei a good value? Or which value would you choose?

[@BigClive]

Derotron It's a trade-off between intensity and run-time. I'd suggest between 47 ohms and 220 ohms.

[@Derotron]

bigclivedotcom Thank you for your fast reply. And its planed as a night light so a high intensity is not needed.