Perplexing Temu solar filament lights
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- Опубліковано 4 жов 2024
- These lights have a really nice case and appearance. I actually had high hopes of them being a great light. They even seemed to have a dedicated all-in-one charge control and PIR monitoring chip.
Then I dug a little deeper.....
A simple diode test between the solar panel input pins and the power pins of the chip showed a single diode drop. So the unit does appear to be using the built in protection diodes of a standard microcontroller. I tested to see if the unit did anything to regulate the charge on the lithium cells by turning on the LED filament to shunt the voltage down a bit, but it didn't.
At this point it appears to be luck whether the lithium cell gets overcharged or not.
Thankfully they're fairly low capacity. The large cell measured 500mAh, the smaller one measured 300mAh.
Two improvements to these lights would be adding a small protection module to the lithium cell, and adding a resistor to limit the maximum current through the LED filament. That will also give longer operational time on a charge.
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Ooooh, a solar lantern that turns into a Tiki Torch
😅😂🤣
Just put some citronella on the top lol
🤣🤣🤣
Think of it as a high UV detector. If the UV from the sun is too high (sunburn), it warns you by burning down the house.
I really love these health and safety devices from Temu.
That would be a large soot stain on the brick wall with some smouldering crap at the bottom of it, if it was on a wood fence/shed then yes.
How surprising that this is made in the quality we'd expect from temu
The surprising part is they went out of their way to make it uniquely awful. Using the input for sensing, voltage “regulation” via the 0.6V drop, and _charging_ the cell is a new low water mark in shit Chinese products.
'For want of a halfpenny worth of tar, the ship was lost.' comes to mind.
Ahhh, so sorry. In China we make crap. Save tar. Suckers still buy crap anyway. Ha ha!
Probably a buck extra for a charge controller to be included
This describes the vast majority of cheap Chinese products.
An exploding lithium battery? Excellent!
Very bright garden for a little while, then increasingly so as the fire takes hold of the shed/fence it's ben nailed to.
Fear not, Big Clive has a FIRE 🔥 CONTAINMENT PIE DISH! 👍🤣
To be fair here, it would explode or melt and catch fire when charging. That would be daylight which means it would be harder to spot the initial fire!
That’s what the -input protection- fusible diodes are for. In the event the something does go wrong the cell will blow those clear before catching fire.
@@ElToro2000UK
Make it an even 30 just in case some do fail to fail :)
I got the exact model, a white one, I swapped the battery to 2000mAh, added a BMS and extended 1.5w solar panel, it last all the night until dawn everyday, even on cloudy day.
every day*
So the house igniting feature comes at no extra cost ...... very impressive.
I think they're meant for sheds, not houses.
About £300,000 in the case of my house! 🤣
@@marcse7en Odd place to flex
Garden igniting in this case
Obviously, this is a custom circuit designed for use only in the UK, where the weather is always cr@ppy... They would have a different circuit for use in Southern California!
Yes, of course they would.
Suuuuuure they would.
Well normally you'd expect that, but we're talking about Chinese ingenuity and logic here "just pump out as many as possible, who cares where they go, as long as they go"
I'll swap diffused sunshine and stable tectonics over skin cancer and a volatile subduction zone any day. At least your solar lights will illuminate your collapsed cities while they rebuild the infrastructure. Lol.
or up north in the summer time where you only have about 7 or 8 hours of darkness... (it would work fine in winter if your house lasted that long)
I "had" a light with an almost identical PCB. I found out that the MCU is 3.3V, and it only lasted for a couple of months before the voltage killed it. I bought a 5 pack of replacements PCB's from AliExpress which had a both a charge controller and a 3.3V regulator for a few pounds, and seemingly the same MCU - same options. These fitted right in and hopefully reduce conflagration risk !
Finally, we have a return to trashy electronics. Nice to see Clive back on brand.
Guts look identical to the solar lights I've had on my fence for years. Solar panels are all yellowed and crusty, surprised they charge, none have blown up yet. Checked the voltages of them after leaving them charging all day and they weren't that high, couldn't tell you just what right now, but of course they absolutely COOK in the sun.
I never liked that fence anyway.
The yellow crusty solar cells are due to the transparent sealant being used on top of them instead of a glass plate. UV damage to the sealant, basically, plus natural abrasion. Its unfortunate that the vendors can't be bothered to put a glass plate over the solar cell instead.
Most bulk 5V solar cells come sealed and the vendors just tack them onto the top of the units directly with no further protection.
@@junkerzn73123M sells a headlight wipe coating that protects plastic lights from yellowing so I wonder if that can also work on a plastic solar panel.
You sure those are lithium cells (which can burn if overcharged) or NiMH cells that basically stop taking a charge naturally when full??
@@kirkb4989 They're 18650 lithium cells. I have a couple I never put up, now I'm curious, think I'll leave one out in the sun and check it.
@@junkerzn7312 Well for fun I put a brand new one out on the fence rail to charge the past couple days. Took it down and the old one - new, battery was charged to 3.93. Old 3.91. Guess more care was taken with my fence melters, good to know.
Also stuck a meat thermometer in them soon as I got them down - 120F. And it's only about 80F today. Toasty. But then anything left in a car, like a hybrid battery pack, is going to get just as hot or worse.
Spontaneous combustion adds to the excitement of a Chinese lithium battery purchase. Cheers from New Orleans
Love those filament LEDs. I've been making garden lamps with them and they put out a lot of light BUT they take 3 v at 100 to 300 ma depending on length. At 4+ volts, without current control, those things are likely to burn out if the bat voltage is too high. I've run them on 4 volts with resistors and also with a buck converter down to 3 volts. I've also run them with a 1.2 v solar board which boosts the output to 3 v, then run that into a low power 555 and made them flash. Makes the battery last a lot longer and adds zing.
There is crude current protection here. Transistor will drope some voltage and with 510R resistor at base and with typical gain of that transistor of just 50 there is some current protection. Still too high for that filament to last a long time but they probably expect people to use this with PIR with ON time of maybe 10-15s.
Have had one of these for about a year now. Been surprisingly good. Bought it off a friend who's business was struggling. Didn't expect it to last past the first rain storm.
_"I am greedy for the big one"_ 😂
Phrasing!
@@Solron78 Context!
Me too.
First time meeting Clive?
@@markfergerson2145 No no, definitely not! I just like pointing them out when he does. =)
I actually wonder if this might have been originally designed for a couple of NiMH batteries instead, and they just swapped them out for LiIon later (because those are a lot cheaper nowadays), without changing the circuit design at all. (I've seen a lot of older versions of this sort of thing designed to use NiMH batteries because you can often just charge them directly off a solar cell without worrying about any additional charge-control circuitry, etc)
Good point there.
Gaz Yorkshire
My thoughts exactly, and a similar comment added above/below. NiMH is the better choice for most temperate areas.
Probably not, tbh. 2 x NiMh cells is only 2.4V. Would need a boost converter to be able to light up a white LED. They usually require at least 2.8V, and crappy Chinese ones more like 3.4V.
I have a 5year old NiMH unit that's barely hanging on. Now indoors and 1/4 of the original stringlight... lights for an hourish Slowly being trickled to death and (not) very impressive.
Ah a foolproof way to commit house insurance fraud.
Here in Australia the battery will likely be destroyed sitting in the sun for a few 40deg days before the crap charging circuit can.
wimwiddershims, yes, one of my many solar lights here in perth stopped working. when i pulled it apart the battery had been charged up to beyond 5v. the battery is now in something else and working fine. i havent noticed such eagerness to overcharge in any of my other lights.
Same for the US
I'm in Texas and NiMH are the only batteries that last the year, but they don't last the night either due to poor energy capacity. I think in my next visit to Ikea I'll pick up some less terrible lights and see if I can't replace their batteries with extra Ikea NiMH batteries.
That's maybe another experiment for Clive, what ambient temperature can an 18650 cope with before it engulfs itself? Curious minds want to know.
@@cheyannei5983I have few solar light from IKEA, and they actually have replaceable batteries. Either AA or AAA NiMh depending on the light. IKEA also used to have lower capacity batteries for these lights. However, they seem to have disappeared from the shelves, at least in my country.
Why is it so interesting checking out cheap Chinese electronics? Love this channel. 🔥
Because chinesium is lovely.
@@andrey8688 and you never can tell by price from the outside, whether you have a gem or junk. Clive is the QC god. That's why so many come here to his temple of tat and pay homage to his great wisdom and fine beard.
Clive was spot on, an amazon review says there light exploded the cell and shows a photo with a hole blown in one side and the contents of the overcharged cell sticking out :o
Direct soldered battery = likely enough space to add a single cell holder, which is nice. Pretty nice looking lights.
Most of the stuff I open up (including laptop batteries has wires welded to them not soldered
@@nedyahyakcam Yeah spot welding for major devices is normal, but theres no telling where those lights were made/assembled though. Not everyone has a spot welder, but Most people have a soldering iron.
Wouldn't soldering make a lithium cell explode?
@@ianhosier4042 Depends on how long you apply heat to it. Doing a quick dab to attach a wire can generally be fine, but extended contact can damage the battery (not necessarily make it explode), which is why spot welding is preferred, much quicker than soldering and less of a chance of the battery getting too hot.
@@ianhosier4042 clearly not, also no i have done it my self
I have those same ones!! They're actually quite bright and look nice.
Edit: Just finished watching the video and I'm wondering if I should throw them out. lol
Hello Clive,
The reason why so many electric scooters and power drills batteries are going up in flames lately.
Any Chinese battery-powered device without a true CE-UK-US safety mark, charges the Li-Ion cells like they were Ni-Cd or Pb-H2SO4 cells. The chargers type don't match the battery type.
I remember the solar light shown in the video, few years ago, used the same circuit schematic and few Ni-MH cells.
A solar light with such charger is a firecracker, but a power drill or a scooter with the same inappropriate charger - is a pipe bomb.
I check every battery-powered device that enter my house, to see if it use the proper Li-Ion charger and battery cells.
Something is not right. The import-export agents should be able to catch all these fiery devices before they enter peoples' homes.
Greetings,
Anthony
I have using those resin coated solar panels for years but I buy the acrylic clear top coat used on cars and give them 2 or 3 coats of this clearcoat before putting them in to the sunlight and they last many years longer almost as long as the glass panels
Probably originally designed for NiMH and the better choice for solar lights in areas with
The flaming wall will add additional light.... But of course that will only happen in the daytime.😂
I heard the quadruple whammy in the style of Stalone and the 80's Judge Dredd. Thank you for that :)
Both were bought by me on ali. For cheap. I removed the cell and replaced it with a protected LiFEPO4 cell. I no longer need an extra resistor, or a very small one. I am running it in the night modus, where it is lit very low and comes up bright after movement detection. I ended up connecting it to an external LiFEPO4 cell which is used for many projects (a 200Ah 3.2 V cell, charged by its own solar panels, and protected). Would i recommend buying it? Yes. For that little money you do your own adaptations, and it looks great! O, and I also added a mirror on the backside, it looks very good now when it is lit up!
I did not do the tests like Clive. There may be a feature he has not tested, who knows? I know those 4 cell solar lights charge up 1.25 niMH cells. The circuit has a clever way of draining too much power in: you will see the LED light up when the voltage goes too much above 1.4 Volt. So maybe, I say maybe: this circuit may do the same? The LED string is capable of drawing a huge lot of current above 4.2 Volts!
Thanks Big Clive. Kind of sad they shave a couple dimes off the cost of producing an item that could actually be good.
Something I learned by experience is not to make lithium ion cells angry (and they have no sense of humor at all), I have a huge box of recycled 18650 from laptop battery packs and many others from other types of e-waste like vapers and old cellphones, i was making a 3S4P battery for a router with a 3S 40A BMS and made a funny mistake, I am glad to always have a metal bucket full of sand close to my work bench just in case of fire, since then i have a double checklist when dealing with lithium cells.
Naah,Clive, no worries..I would definitely buy one and mount it to a brick wall..the worst that can happen there are scorch marks, hehe 🙂
I have seen this type of circuit in solar light for several years now (I actually mentioned about it in one of your videos ages ago). Now every time when I buy a new solar light, I have to open it up and check the circuit first. But in the end, I have to add the BMS pretty much every single one of them anyway.
Its actually quite elegant, if they programmed it properly. I could easily make something like that work with a PIC8 or PIC16 microcontroller pretty-much as-is, just with decent firmware coding. Whether they coded the firmware properly or not is another story, but I'll tell you how I would do it.
* The protection diodes in the PIC chip will work just fine for this application. Remember that the solar panel itself is actually a diode as well, so all the protection diodes in the PIC chip are protecting against is reverse leakage, which will be micro-amps, and also powering the microcontroller when the sun is down... but the microcontroller doesn't pull very much current, so that isn't a problem.
In the old days of HCMOS we used to power portions of the circuit board with HCMOS gate outputs instead of directly from the power supply, allowing us to control power to various parts of the board. This works the same way, albeit somewhat less efficiently. But the reverse-biased current is going to be so low it just won't matter.
* The microcontroller can easily burn however much power it needs (within reasonable limits) to keep the voltage of the solar panel down... if its firmware is coded for that. In otherwords, we would be relying on the natural current limit of the solar cell to control the power.
There are multiple ways to do this but the easiest is to just turn on all the internal peripherals and eat cpu cycles... or just turn on the LEDs... or have a pin control a resistor to ground to bleed power.
* I would expect the microcontroller's absolute maximum voltage tolerance to be 6.5V or so in this situation. And it probably works down to roughly 1.5V. But yes, if this is a standard lithium cell it must limit the voltage to 4.2V or lower for safety.
To test that you need to put a current limit on your power supply roughly similar to the solar cell... but it still won't simulate the solar cell because the solar cell's voltage drops linearly with current while the power supply voltage doesn't drop at all until the current limit is reached.
So test with the actual solar cell and see what it does.
* Charge current is naturally limited by the solar cell.
* The microcontroller can trivially monitor all voltages on its pins and simply cap the voltage on the lithium cell by burning cpu cycles or turning on the LEDs.
So... I could definitely make this work. Whether the vendor did all of this properly, however, is another story. If they are using a lithium-ion cell instead of LiFePO4 then I wouldn't trust them to get the firmware right either... the product will fail after a year or two with a normal lithium-ion (NMC) battery.
But yah, this is really elegant... the hardware that is. I would probably build a circuit just like this. But of course I would program the firmware properly.
Addendum:
* Double-check that lithium cell, it might have protection built-in.
* On current-limiting the LEDs.. You don't necessary need a current-limiting resistor when driving LEDs. Well, you definitely don't for current-regulated LEDs. This particular filament is not current regulated-though, it is voltage-matched.
This actually works as long as the voltage does not exceed the optimal value by too much. All that happens is that any voltage above the optimal value dissipates as heat in the LEDs. So the LEDs will run hotter, basically. This is fine as long as they don't overheat. The limited capacity of the battery itself means that the voltage drop of the cell when the LEDs are on (the internal resistance of the cell) might be enough.
Another way of dealing with it would be for the micro-controller to simply PWM the transistor based on its voltage reading of the battery.... if the firmware is smart enough. I could certainly do this quite trivially.
-Matt
Chicom quality is legendary!
Solar-powered garden bomb. Yay!
Not here in the UK fortunately due to our crappy weather
@@ianhosier4042 Fair point. Unlikely here in Seattle, either. Perhaps this product is really intended only for perpetually overcast environments!
It's possible Q1 is a prebiased transistor with an inbuilt base resistor and pull-down. They're pennies per hundred, but I wouldn't be shocked to discover it wasn't
We know size really matters ☺🤣
They do look nice lit up, but no SOS mode 🤷♂ A flicker flame effect might be interesting, make them look a bit like coach lights. ( but plastic) I like how the "glass" unscrews. Nice lights 2x👍
I was going to joke about "what, no SOS mode?"
You mean the SO mode? I've never seen one that actually does SOS properly...
@@georgeprout42 now that I think about it it is just SO over and over again.
Maybe it's made by BYD, power optional, fire guaranteed! Thanks, great video. 👍❤️
Makes a change to see good antiphrasis design, not only the circuitry, but also ingress protection and secure battery-holding techniques.
It’s not that ‘strange’ these days, everyone is doing something on the cheap….feels a bit like war, survival and all that. If ever a big Clive video needed a follow up, this is it. Great work as usual.
Thanks to Louis Rossman, I prefer to buy such items at local stores, even though it costs more. That's because local stores have an incentive to keep customers happy, as well as not having defective items returned. If the item isn't available locally immediately, I stick to brands which are offered via mail order by those stores. For example, I recently bought Westek night lights online because Ace Hardware offered them.
I also have one of these. I thought for certain that it would immediately be penetrated by water and fail, but it has held up well through fairly severe storms.
That said, I've taken it down.
It would be a good idea to put a 1N4002 in series with the solar cell to reduce the maximum voltage that can go to the battery. It might take more than one, or a combination of a 1N4002 and a 1N5817 Schottky rectifier in series to add up to enough drop to limit the battery to 4.2V. Another way would be to connect a 4.3V, 1W zener across the battery to absorb any of the current above 4.3V.
Like the zener idea; easy and cost effective (just guessing)
It would have to be a 5W zener but yes, that would... well, sorta work. Zeners below 5V have very soft "knees" on the I-V curve, however, and the reverse leakage current may be too high and destroy the battery. You'd also need a current-limiting resistor because if you let the zener overheat and melt, it basically becomes a dead short. So that opens a can of worms.
It would be easier to try the zener idea with a LiFePO4 cell which can be charged to 100% anywhere from 3.45V to 3.65V and tolerate 4.2V. But still a can of worms.
The easy solution is for the micro-controller to just turn on the LED filament unconditionally to override the solar cell when the voltage exceeds a certain value. I little PWM regulator using the LED.
Temu - the gift that keeps on giving. 🤟😂
Buying Temu sh1t3 so we don't have to. Thanks for taking one for the team BCDC, although to be fair, I will never, ever, purchase a single thing from Temu, so there's that.....
it’s a pyrotechnic backup lamp, so when LED goes out you’ll have a nice bright lithium fire to illuminate the way👍
6:20 ah good you did talk about that. we have these exact same units in Dollarama in Canada. I have been buying them and monitoring their voltage with an ADC and ESP32 to see if they are a good source for solar charge controllers. And has you have discovered they are not, they overvolt the batteries.
The good news is that the physical solar panels are also so shit that they current limit themselves after getting too hot somehow. I'm not really sure how but I confirmed it with my multimeter on the bare solar panel wires not connected to anything else, and if you stick them in full sun, you'll get 50-100mA for a few minutes, and then instantly it'll drop to anywhere from 30 to as little as 4mA. And it just gets stuck there until it cools off again.
They also sell them at Canadian Tire but the reviews just say that they stop working after a while, not that they explode. I think the low capacity cells just leak internally.
It would be possible for the microprocessor to limit the voltage to which the cell is charged by turning the lamp on if the voltage is getting too high. It would be possible as a modification to connect a diode in parallel with the transistor, selected for forward voltage drop so that the sum of its forward voltage and that of the lamp is between 4 and 4.2 volts. This will allow any overcharge to spill safely via the lamp, causing it to light to some extent.
clive i really like the look of these i vote YOU build a proper circuit with the PIR and battery protection show them how it needs to be done
I live near your old stomping ground in the Garnock valley Clive. The chances of overcharging here are pretty much nil 🙂
I've got a similar one from Temu, the bigger version. It does have the 510 Ohm resistor in the base circuit of the transistor. But the battery while indeed Lithium, is not 18650 (even though there is a room for it), but some kind of unlabelled AA-sized one. Also there is only one screw at the back, the rest are clips. I measured the voltage coming from the Solar unit at full unclouded sun, it is 4.83 V. The current going to the LEDs at full brightness is 203mA. So it looks to me that a single standard diode in the charging circuit of the battery shoud provide sufficient protection from overcharge. As to how long will the filament last at 200-odd mA, I have no idea. And btw, the edges of the Solar battery provide ample opportunity for water ingress, definitely some king of epoxy glue or putty will be required there.
got a set with the panel on a wire..has a metal lantern thing and pull cord switch. really good. lasts all night, brightness settings and a remote and its bright enough for my tiny chill room to read and whatever.
was curious what voltages the bulb was running on. doubt the battery is anything so its gotta be efficient.
also its a really nice warm light that has 0 flicker 🙏
They look nice!
Hey Clive. If you haven't seen the SNL sketch about Xiemu, it is worth a watch. It does tend to focus on clothing products rather than electronics, but I think the jokes are pretty much equally applicable to both!
My father bought few similar ones long time ago on some "facebook sale", first battery died after one sunny day. Rest of them died that same week. After seeing that battery I put in first one died at the end of that same week I finally checked and sure, no battery protection on board. These at least have LED resistor so premium version I guess :)
I added two normal diode in series with solar positive, it's not perfect as voltage drop is around 1.2V but with any current that rise towards 1.3 so...let's call that close enough :)
All of them works for three years now without issues, even spending winters outside using recycled laptop battery cells. Ideally adding one more schottky diode in series would be perfect, keeping cell voltage around 4-4,1 prolonging life of cells but even this work fine.
Temu, what did you expect.
Bought two of the "120 LED Solar Street Lamps" from Aliexpress and both charge the battery over 4.3Volts. Still working after 1 year, nevertheless. I think I sent you an email with photos of one of them after a storm knocked it off and flooded the interior.
It seems fine to me I really like the end of life warning I figure it will work until the one day the LED blows from over load and incase you don't notice the next day it will over charge and light on fire so you definitely notice lol
Maybe there is a zener shunt in the chip to prevent overcharging the battery? There's not much power from that small solar array (1 watt maybe), so it would work fine.
In the far distant past, you reviewed some LED screw in bulbs that I believe you bought at your local pound store. We have a similar store here in the US called Dollar Tree. I bought several after watching your video and I have been well pleased. Since I don't have a Dollar Tree close by, I when I am near one, I buy 3 or 4 just to keep on hand. Recently, the Daylight bulbs have become scarce so when I was visiting another city I found some and bought 8. All my ceiling fixtures are the dual socket type. A bulb burned out in one and I replaced it with one of these recently purchased ones. To my surprise, it didn't work. Thinking it was a bad bulb, I tried another and it wouldn't work. Thinking maybe a fixture issue, I took the bulb out of my workbench light and put it in the fixture and it worked. I tried both the new LED bulbs in my workshop lamp and they both worked! I tried them in three different single socket lamps and they worked. I tried them in two different two socket fixtures and they will not work. Even if they are the only bulb in the fixture, they won't work! Both two socket fixtures are wired in parallel. I went to my local discount store and bought a brand new two socket fixture thinking there was something strangely wrong with my fixtures. Same exact result. They will not work in a two socket fixture. Do you or any of your highly technical viewers have any idea what the heck?
I responded to your email about this.
I have three of these,one out of action due to the solar panel loose and a broken lead. Still have one functioning. No trouble yet. The third is on standby just in case.
There's a bloke somewhere in temu watching Big Clive videos and taking notes...
ST Microelectronics do a couple of lovely energy harvesting ICs (SPV 1040/1050) which offer MPPT, boost, CC/CV charging for a wide range of cell chemistries and work as low as 0.45V I/P.
i believe that it can't overcharge because it will be spend on the motion sensor daily so it will never actually reach 4,2V+
Adding a string of diodes between the transistor base and positive rail so the transistor turns on when the voltage reaches about 4.3V would give a degree of basic overcharge protection. Nothing to protect the battery from overdischarge though.
A little strange to have the screw in bulb cover, makes me think they murt use other styles in other applications, otherwise I'm pretty sure they already make an all in one package (infact I know they do as I've seen them in tesco 😂)
Perhaps the over-volting suggests why the battery capacity was so low, you said the cell puts out 5.5v but don't diodes take 1.2v away, leaving 4.3?
Typical silicon diodes will usually drop .6V. Putting two in parallel increases the current limit, but doesn't change the voltage drop.
@@strehlow possibly I'm thinking of something else but I'm sure at least one will drop 1.2v,odd
I do find myself missing the rattle of that cheapie pen screwdriver that you had used all the time. Bring it back pls!
The latest temu deal; buy a bulb, get s free BOMB!
So, my guess is the the lantern is designed to run the battery flat every night. At a high latitude, the solar panel might get 16 hours of productive light at summer solstice. As long as the panel puts out no more than 31 mA at 4.3 V, then there isn’t much risk of over charging the 18650.
Something like this but with 2-4 user replaceable standard NiMH rechargeable AA batteries(!!!) would be great actually. And no fire danger, because NiMH don't explode.
Not sure about this particular one but I believe 18650 cells often has a built-in protection circuit
It's rare and usually obvious. The internal pressure operated contact is a different thing.
'For Want Of A Nail' In product form.
I think it should be fine, explosion-wise.
The pv panel looks like barely pushing 50mA peak and the cell would require 10h of straight sunshine - which just can't happen. But even if in pir mode and next day the cell is still full, 50mA just won't cut it to detonate the cell.
Degrade it... yes. Kaboom... probably not.
After 4.2v the esr shoots up and the cell disipates the energy as heat. Put in enough energy and the electrolite gets decomposed and evaporated.
Your bench supply can, the tinynpv panel can't.
If only the micro had a power supply monitor circuit that caused it power up and turn the LED on if the voltage went above a certain threshold..
In principle, if the device had an absolute ADC, there are a number of ways that this could be 'safe' (still at risk of overcharge in crashes). For example, short the solar cell on the input by driving the input low, when >4.2V occurs. Or for perhaps even cheaper, compare the LED voltage Vf to battery volts and use that as a reference. If you know the capacity of the cell, and time how long the LED lasts, you can internally measure capacity and ensure that integrated charge is under that. All hacks. Some may even work.
Safest Temu product
Please test the circuit by power it by a power supply. We need some more explosion in this channel!
I'm really struggling to find some good solar lights like these. I bought a few, several years ago, but they're pretty terrible when it comes to their sensor angle, the solar panel not charging consistently, and their on time. They all either stay dim and brighten up when they detect someone, or stay on for 10 seconds and then shut off. I'd love one that stays on for a minute or so, then shut off.
The ones I have also dont turn on most of the time as they seem to struggle to charge.
Yeah, disconnect the battery and put it under a light.
The voltage going to the battery rises above 5V.
I just tested an example.
The battery does not in my experience catch fire, but does degrade over the period of a few weeks to the point that it no longer stores energy.
They are bad, very bad.
But then , I have a very caustic opinion of the solar industry in general, not much of it is actually worth buying.
I can confirm your findings. I have two of those, only difference being they include a led array. Chip/transistor markings are the same and board layout similar. It has no charge controller and kills the cell quite quickly. In my case it lasted a year, but that is in Ireland with two sunny days per year. They go high impendace as you told me in a earlier reply. So you think protected cell is enough to make it work, or a inline charge controller is needed?
My choice of upgrade would be a cell protection PCB. Or use a cell that already has protection.
those e27 plastic "bottles" I would buy if sold separately.
All they had to do was use an ADC (assuming that uC already has one) to sample the battery voltage when charging and turn on the leds when an overvoltage condition is detected.
I pulled apart a Dyson vac battery that had failed. The first word that came out rhymed with truck when I saw 6 Li-ion batteries in series with no BMS! Yep, just series charge them with no monitoring of cell voltage. What could go wrong eh?
How about sending them to me in Florida... I would love to see one torch up.
Sad that the case was just cheap plastic.
It makes my day when Big Clive says "Aluminium".
"4.9V on a bright, sunny day". DEFINITELY not a good idea for Australia for most (if not all) the year! "Why is the Solar Wall Light smoking, Dear?" comes to mind :-D
Shurely the only thing to protect the li cell is a resister and a zener a bit above charging voltage across the li cell
Thank you, keep working.
Looks like this lamp needs the addition of a 1S BMS for the cell and an upgrade to the cell capacity
Also without battery protection circuit, the battery could become over discharged.
Gaz Yorkshire.
For such a low capacity, Are they just reusing old cells, I'd doubt they're ordering new ones,
It may be reclaimed cells or budget ones.
Nice!
They could monitor the solar cell voltage, and then the odd on to shunt power on a sunny day...
It's surprising, how much effort goes into producing waste.
The older solar lights that use NiMh work great.
My parents have some in their garden for years without changing the batteries which must be several hundred cycles.
My mother in law has some crappy chinese garden lights.
After 2 years the plastic went so yellow that you couldn't even see the solar cell.
After 3 years I thought I'd try to polish the plastic and when I touched the first one the cover shattered into a million pieces.
So I didn't touch the others which are now 10 years old and are mostly decorative in here eyes and an eye sore for me. How can you even make battery powered leds flicker. She just doesn't see it as she goes to bed early.
I have to wonder if the interpretation of how a solar cell performs is affected by the crippling levels of smog in China. Perhaps, in order to save on labor, these were designed by a gradeschool-equivalent science class with a "measure and function" design philosophy common in primary education. Or, perhaps, they just don't care at all and want to get the cheapest possible thing out the door for maximum profit.
It's Temu, so likely the latter option.
Uh oh, I have a similar light to this, the regular LED panel varient. bought from 5 Below (US shop similar to Pound World), mounted to our wooden shed. Granted, it was bought from an actual shop and not Temu, this could just be a crappier version without charge control.
Wouldn't be bad if they had simply used a protected 18650 for a few cents more.
Products like THIS are why I tore off and kept a bunch of the protection PCB's off dead 18650 cells. Slap one of those in there along with maybe a larger cell, and you'd have a fairly decent light.
I have the one on the right, doesnt work well on dusk till dawn mode but left on motion activated only it works pretty well
it looks like that back cover will leak, requiring it to be installed under eaves or inside a house, defeating the purpose of having everything built into the one package.