A look inside a 1W LED emergency light.
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- Опубликовано: 26 авг 2024
- I got this on ebay, purely to take to bits. That said, it's actually quite neat and only draws about 1.5W standby power to keep the batteries charged.
It contains a switchmode 5V supply and the circuitry required to keep the batteries on what I guess is constant trickle charge. In the event of a power cut the white LED will illuminate for at least three hours. When power is resumed the battery pack will be charged again.
The video also has my take on the cheapest and possibly tackiest Chinese style emergency light circuit possible. Like a challenge to design an emergency light with the minimum amount of components possible.
But in my last-minute addition there's a design flaw. With the LED in series between the switching circuit and the cell, the voltage available to turn on the transistor would be so low that it would probably allow the LED to glow, but not light fully. A fix would be to add another cell to make a 4.8V (6V peak) pack. But that would defeat the whole "cheapest possible" thing. (But might allow the addition of a rectifier across the LED so it glowed to show the battery pack was charging, and then lit at full brightness in the event of a power failure.)
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"Let's design a chinese-grade one."
Dammit Clive! This time I sprayed wine on my monitor.
>.
you sprayed piss all over your monitor
You're assuming a cheap Chinese manufacturer would actually include batteries and not just toilet paper tubes. That simplifies the circuitry considerably! :)
The "luxury" of a discharge resistor. Love it. Thanks Clive!
they are sub c cells. found in power tool batteries. they have a really high discharge rate, hence why they are used in power tool batteries.
What a handy comment, was looking to replace the NiCad cells in my old battery circular saw.
I've been in crawlspaces and seen emergency light fixtures from back side. Those were wired in series and in the end was the customary yellow-green cable connecting the last one to the earthbus. That way you did not bring the earth from the battery fixture to each light separately.
If there is sub millimetre isolation at any point, then it simply ISN'T good enough. Time after time I have to check and re-check my own circuit designs to meet the safety standards for electrical creepage and clearance. Yet millions of potentially unsafe equipment like this is made and sold marked as safe.
We've got some new LED emergency lights at work (bit different design to this) and in a recent power cut I noticed that they're not really as good as the fluorescents in a translucent diffuser box units they replaced. The LEDs give you a very small visual target at ceiling level and it doesn't particularly look like it's telling you which way leave the building (the fluorescents had a green arrow on them). The LED's project a vertical beam onto the floor (which as it happens is quite a dark colour) - you could see an obstruction on the floor if one was there, but if not it's not really very apparent that that 1.8 ish meter circle of dark floor is being lit. very little light being splashed around onto walls etc, disorienting.
Think these things might be found wanting in real emergency evacuation situations TBH and something that looks like the boxy diffuser emergency lighting units people have come to expect over the last few decades (probably containing LEDs) is really the best way forward.
joinedupjon In my workplace, the traditional emergency light boxes have been replaced with a more modern type, the same size as the old ones, but containing white LEDs instead of a tube. For some reason, the non-maintained type get replaced by constantly lit types, even in normal rooms.
joinedupjon what’s even worse is the LED bulkhead emergency lights mounted over doors... All the light shines sideways and bugger all ends up actually lighting the doorway or the area around it. Fluorescent was miles better. And what’s the point anyway? They are only lit during a power cut so the energy saving is moot...
I remember once seeing a combination of a night light, emergency light and torch in one, which I think was an Aldi special sometime last year. It plugged in and operated like a typical night light, but had an internal battery to keep the light lit during a power cut. I can't remember the power rating, probably 1W. A few advantages with this for home use would be the ability to just plug it in instead of requiring an electrician and being able to unplug and carry it around during a power outage.
Handy little things, quite interesting LED solution also. Nice video, thumbs up.
You should do a teardown of the Sylvania brand cylindrical night-light/power failure lights...I have had a 100% failure rate on them within 2 months, the failure seems to be the pack of coin shape batteries failing (seperating at the seams) in charred flakes
ive fitted loads of these at work, good little units, and cheap!
nicad is still allowed for portable power tools, justified by the cheaper pricepoint,(the EU have extended its exception several times) but im sure the lights are nimh, they dont need nicad anyway (nimh cant shift the high amps needed for power tools)
the batteries look similar in size to what you get in most older 12v-14v drill batteries.
Design Flaw noted a the end: The charge and discharge LEDs were drawn backwards (or labeled backwards.)
Your screwdrivers are quite nice, can you make a short video about them? Seem somewhat special...
There're just roslon from maplin ect
They're just cheap crap from lidl's.
Back in the day (dinosaurs still walked the earth in those days) when I had some involvement in emergency lighting, they could be 1, 2 or 3 hour duration. Various complicated factors dictated minimum duration in particular circumstances.
Oh, and the durations were basically what they were advertised as, not what they actually did (as long as they lasted at least as long as they were advertised to).
I have no idea what the situation is now, although a quick google suggested that they still come in those three durations.
I can remember those old emergency lights, they had a small, almost motorcycle type of wet cell battery in them, then two large flood lights. We had them in the barracks back in the 70's. If I remember right they only stayed on for about 30 minutes then faded to black. We rarely ever got to see them in action, not a lot of power outs down in Texas back then, and since I lived in base housing with my wife and kids, I was only in the barracks during duty hours, and we had really little need for them then. I guess I do recall having a power outage once when I was pulling CQ duty (Charge of Quarters NCO baby sitting the privates who lived in the barracks at night) that we did have an outage seems only a couple of the lights even worked, but we carried a large flash light, nearly as big as the kel-lights I would carry as a peace officer later in my life so the need for the emergency lights were minimal, and the troops were supposed to be in bed and asleep anyhow, well those who weren't high as a kite on what ever their favorite drug was back then. Usually pot as the smell in the hallways would indicate.
I guess the voltage drop of the green LED would prevent the battery from reaching full charge? or at least make it too slow to meet the recharge time
There's no negative return for the LED's on the top rail. They are after the Bridge Rectifier so the rail they're sitting on would only ever be positive? If I'm wrong blame Stow College! :)
Nope. Theoretically the negative would be via the resistor and transistor.
bigclivedotcom Have them biased like that would be a dead short? No resistive load? Help!
BigGoucho The resistor would still be in circuit above the transistor.
What switches the transistor in the off state.
That's definitely not legal in Canada .All the mains connections need to be in a box that's accessable.Nice little device though .
Cells are CD size, a very common one used in power tools and such.
How can i repair an emergency light has no power? I also check fuse, diodes, capacitors. How can you help me with this?
I don't like this circuit. The moment battery pack will degrade with age or will be disconnected from the circuit full mains voltage will end up passing through this 25v capacitor blowing it up. There should be some zener diode after the bridge rectifier to prevent this.
That's a bonus, it means the customer has to buy a new one sooner than otherwise mandated.
Hi, please make a video on converting a 110/220v cree LED bulb to operate on only 12v. As I have been plagued with power outages, and need an alternative to the flash lights and oil lamps I've been stuck using.
+Coffieman5150 You can buy 12V LED lamps as standard.
+Coffieman5150 Maplin have them and the caravan and narrowboat community use a lot of them as they generally only have 12 v unless the engine is running. Although with inverter tech this is changing. But for lighting it is usually 12v dc.
edit ...Is it safe to mention Maplin? (hides behind sofa)
well mine is a 2w emergency bulb with remote and it has about 6w of light
Have you tinkered any more with the little design you came up with?
zendell37
Indeed he has...
ruclips.net/video/RuFGBkYMKpk/видео.html
I am seeing another possible flaw. If the batteries are significantly discharged would you end up blowing the arse out of the green LED if you plugged it in?
+Nick Hodder If you're referring to my doodled minimalist version, then no. The capacitive dropper supply would limit the current through the whole circuit regardless of the battery voltage..
+bigclivedotcom Just did the math. 7.5mA. Not enough to do anything spectacular. :)
Those are probly standard 18650 batteris
what kind of battery it is? liion?
They look like "sub c" size cells with a flat top, so that would limit the chemistry to NiCd or NiMh. They used to be common in RC and tool batteries, and they are common in "dumb charging" devices since they can be continually charged at low current.
Due to the voltage (3.6) and the 3 cells in series with no balancing this can't be a Li-Ion pack. Ni-Cd and Ni-Mh are ~ 1.2v each.
Could i get a link to the listing thanks clive
Just do an ebay search for led emergency downlight and you'll see quite a few in a wide price range.
The battery pack uses a clip for earth so there are no sharp pointy things around to punch a hole in it
Is it just me or does he kind of sound like scott manly
Nobody has the answer yet? (Or at least I didn't find it in the comments). Well, let me give it a try then. We'll disconnect the mains. What turns the white LED on? The transistor. What turns the transisor on? The white LED. It seems like there is a chicken and egg problem. I might be wrong. Haven't done any electronics since the 80's...
Oops! Didn't notice the description... Pressed "Show more" and there it was. Well... I was kind of wrong. No surprise. :)
Ebay seller?
do you have the link to where this can be bought
+Tim Gomes It was a random ebay purchase.
+Tim Gomes in case you haven't found it yet, www.ebay.com/itm/EMERGENCY-LED-DOWNLIGHT-Non-Maintained-3HR-NM3-Light-1W-Office-Home-Spot-Lamp-/131191053024?hash=item1e8b989ae0:g:l~oAAOSwT6pVuL6Z
+Tim Gomes www.ebay.co.uk/itm/EMERGENCY-LED-DOWNLIGHT-Non-Maintained-3HR-NM3-Light-1W-Office-Home-Spot-Lamp-/131191053024?hash=item1e8b989ae0:g:l~oAAOSwT6pVuL6Z
+Doug Reed He asked for a link, so he knows that.
How is it connected to mains potential in the attic? Our (USA) National Electric Code requires all permanent wiring to be protected by some sort of conduit and connected inside some sort of junction box. I'm trying to envision how to connect this. (Loose wires or extension cords are not legal for permanent connections, although some people use them anyway. I could tell you stories of extension cords stapled over doorways to connect an air compressor on one side of the door to a receptacle on the other!)
+Chaplain Dave Sparks This would be connected into a suitable lighting outlet box and then the modules (linked by low voltage wiring) would lay on the ceiling in the same way that electronic lighting transformers do.
Just to clarify: that's "low voltage" in the sense of "under a kV", right? Because they seem to have mains input...
"I'll be Chinese about it"
你妈妈同性恋大声笑
why charge them constantly? should be charged only when the level drops below let's say 80%. there is no load under normal circumstances. batteries tend to lose charge in time but it takes months to drop from 100 to 80 right? so they would be charged in 3 years only 20 times or so.... batteries should be like new
+Szymon Krasuski NiCd and NiMh cells in these applications tend to have quite a high self discharge current. They are designed to be trickle charged continuously, which also simplifies the circuitry.
+bigclivedotcom why is that, and can it be fixed?
+hornylink It's just the nature of the technology. It is suited to an application like this because of its ruggedness.
Nicd and nimh power tool batteries tend to self-discharge to flat in weeks. Which is why lithium ion screwdrivers are so much better...
Unwaxed aluminum threads make my least favorite sound.
11:46 Bang
Wait Why is Cadmium banned?
Because it's needed in cadmium photocells and therefore must be banned. Just like mercury was banned from tilt switches because it made a much better contact than a small ball bearing rolling about inside.
Wait, was mercury seriously banned because of that?
No, but it was another material that should not have been banned, since it was the only one that could do such a good job.
Similar to how they're banning leaded solder more and more
because crazy lib-tard poloticians think its dangerous
You could go and get a job in China :)
After watching this video, I think he is Already employed by the Chinese to make shitty emergency lights and LED lights......
He designs shitty circuits for them, and then reverse engineers them on his channel, pulling apart their various practices.
I just have to varify my suspicions with my underground sources in China first before making further claims. 🤔
dude i like your vids but hope you read my suggestion please dont say is the chinese made it you should instead say china ,cause is the country which is creating cheap crap the people are fine is the country that suck. Hope you understand i feel it is kind of racist like your looking down on chinese for being cheap and have no standards. But thats not true is the country china that have no standards but the chinese people came to my country (Singapore) they are great for their standards dont see any problem with chinese people.
In some of my other videos I do correct myself. I have a lot of respect for the overworked Chinese workers. (In fact I respect ALL workers.)
+bigclivedotcom thanks for your honest and respectful respond your videos are great i like your videos where you take things apart like i always do hope u do more and intresting videos i will always support your channel