This is a fairly common type of LED keyfob on ebay. It has a rotating front bezel that turns on a single LED, and a USB plug covered by the rear cap that is used to recharge the flashlight.
Inside is a lithium cell and the charging circuitry....
Inside is a lithium cell and the charging circuitry....
Don't use that: Rocket science is so easy that five year old kids fire rockets today. Change it to brain surgery, cause that is really not easy.
keychain can be powerbank and solar power
unboxing
How much mAh have this battery?
Alternatively, you could call this "A beginner's guide to reverse engineering an electric circuit".
A lithium battery without charging control – I wonder how many of these went >>>BANG<<< over the last six years, or even how many have lasted that long. I wonder just how big a bang they'd make?
this was simply awesome, I can't believe I didn't know this channel. You can't possibly imagine how important this video was to me! I was about to tell a client it was ok to leave ten or so circuits exactly like this one permanently connected to a powered usb.
If the Li-ion battery is damaged later on, is it possible to remove it and use the flashlight directly from USB supply?
I bought one of these flashlights and it actually has the red and green LEDs for charging status, so it might be different inside. It would be interesting to make a follow-up video 😀
I got one of these but the problem with mine was that the switch was shitty and it didnt made a proper connection. Mine had the red led when inserted to usb charging. However no charging circuit whatsoever just some ressistors and a diode….. -.-
I have seen a similar diode and resistor charging arrangement used in some really crappy MP3 players sold on Ebay. I've never tried leaving them on the charger to see what would happen.
I tried recharging mine whilst connected to a 'Charger Doctor'
and it never went down to Zero Amps —0.03 was the lowest it went.
But it does have a Red LED when charging
–I never saw it go Green.Firstly this has saved me doing my own tear down, so i'm a happy bunny today \o/
Secondly i'm a little confused because I ran mine for about 3 hours to run it flat so I could find out what the charge current was (my USB voltage/current meters don't even register it), but if it's driving 120mA into the LED and the battery is 50mAh, then the numbers just don't add up.
This is likely because the current is going to drop drastically due to the low battery capacity, so by 80% charge it's going to be 3.9v and by 20% charge more like 3.7v, which would equate to an average of maybe 60mA between those two points. By the time the LED goes out, you've basically run the lipo cell down below it's minimum voltage.
Charging wise, average 5mA @ 5v, 50mAh battery, it's probably going to be between 8 and 10 hours before you've actually got that battery up to 4.2v
These things are just as bad as those very cheap MP3 player from ebay which work quite amazingly well and also sound good but the charging circuit is exactly the same as this one, so one actually failed on me and when I tried to replace the battery, I wanted to use a battery from a broken Ipod Shuffle and maybe I must have wired the battery backwards because the thing never worked again. The second MP3 battery lasts less and less but oh well, I guess that in the end you could attach a phone battery to it and make it lasts for weeks. Cheers 🙂
Hello Clive love the videos mate . The new quote of the day is "Tender loving violence…."
I wonder if that torch would work better with a higher capacity/wattage led.
What sort of beam do you get out of it in the dark mate ? I do a lot of work in the dark driving trucks and any cheap battery powered light source is handy for me.
Dan.
enjoying your uploads clive…ive been learning some the basics of electronics recently and am finding you teardowns and explainations very helpfull….thanks from sunny govanhill
Great review, I love it. You explain everything very well, and the teardown part is great.
Based on seeing various eCigarette fires on the news, all of which caught fire while charging, those tiny Lithium Ion batteries are quite flammable. I'm surprised there is not even something like a passive zener across the battery to carry the current once it reaches a certain voltage, as I can imagine that that most people will leave this constantly plugged in to a USB port apart from when in use just like with a cordless vacuum cleaner.