I bought these a while ago and thought I'd make a quick video about them while the lithium pack featured in recent episodes was being charged in a non-compliant manner.
The neatest thing about these lights is that the series resistor (100 ohm) is inside the USB plug itself, and has been chosen to run the LEDs at low current (about 1mA each) which will result in very long runtime and operational life. The resistors dissipation is also low at just 40mW (0.04W).
This style now seems to have been replaced almost completely by the newer copper-wire based LED strings and for some reason the seller's profile would not show up on eBay.
As mentioned in the video, these lights are best run on small power banks that shut the output off completely when the internal cell is running low. Some older power banks just turn off the boost converter and the lower cell voltage will still continue to run the LEDs at lower voltage with the risk of over-discharge if left in that state continuously. The use of the smaller packs with 5V on the output continuously is preferred as the bigger "intelligent" packs may just shut off the output with such a low load and will also probably draw more current for their own internal electronics than the actual LED string.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
http://www.bigclive.com/coffee.htm
The neatest thing about these lights is that the series resistor (100 ohm) is inside the USB plug itself, and has been chosen to run the LEDs at low current (about 1mA each) which will result in very long runtime and operational life. The resistors dissipation is also low at just 40mW (0.04W).
This style now seems to have been replaced almost completely by the newer copper-wire based LED strings and for some reason the seller's profile would not show up on eBay.
As mentioned in the video, these lights are best run on small power banks that shut the output off completely when the internal cell is running low. Some older power banks just turn off the boost converter and the lower cell voltage will still continue to run the LEDs at lower voltage with the risk of over-discharge if left in that state continuously. The use of the smaller packs with 5V on the output continuously is preferred as the bigger "intelligent" packs may just shut off the output with such a low load and will also probably draw more current for their own internal electronics than the actual LED string.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
http://www.bigclive.com/coffee.htm
i have a led fairy lights the runs on two CR2032 battery…i want to convert it into USB…what resistor value should i need in order to run it via USB port?
how to fiz battery
Hello great video.. Thinking about buying these for my daughters room once you charge them up and plug them into a charger can you detach the USB port and then the lights or strained by themselves and I can put them in objects or do the lights have to stay plugged in to a USB port to work? Thank you so much
Great videos bigclive!! I have enjoyed the KNOWLEDGE passed along and have purchased several project-worthy, take-to-bits, fun things based on your channel and have bought a strand of the RED fairy USB powred light string. One thing I did notice after some time lit, that they were WARM!! I pulled out my charge Doc usb charge meter and saw it was drawing a FULL 1A from my power bank. So further investigation is called for as the other strands I ordered and received, all draw as you found, in mA rather than a full Amp. Thought I'd pass this info on to you and your viewers!
I got a set of LED 'fairy' lights today at our dollar store. It was the only set left which was disappointing. Cool thing though, I found where they crop the wires off. So if I find more sets I should be able to daisy chain them back together. I wonder how many LEDs two AA batteries can run though.
Clive (and others!): my brother is looking for some LED lights to use in a display cabinet. I was think that some of those flexible self-stick jobbies that come on a roll, and cut as needed, would probably do nicely: so what do I need to look out for etc?
Nice simple lights
Big Clive did you check the USB connector to see if there was anything on the data connection pins, captain paranoia is leading us to believe a lot of USB powered things now are being supplied with virus and malware so they infect your pc if you you plug them in.
Pound shop, they have strings of led lights in the pound shops, oddly enough there are a lot good little bits and bobs in the pound shops nowadays, things that used to cost a great deal more than a pound only a few years ago, including small solar panels, camping knives, screw drivers and a whole host of things that can be very useful including phone chargers and low level pocket power banks.
Love Patreon!
A Question: Since there is 2 V voltage drop by the 100 ohm resistor then the USB voltage delivered to the LEDs is 3 V at the current of 20 mA. If the LEDs are set in parallel then each one must be switched on by only 1 mA and if they are set in series then each LED should light up by 0.15 V (3 V/ 20 ) . This does not seem right. Does it?
How long would they run on a car battery?
Clive, I've used Poundland USB power banks to run a few simple led circuits but sometimes they cut out after a few seconds. My assumption is that they require a minimum current draw. Is this the case and is there an efficient way to overcome this?
Sometimes the simplest things are the best.
As always, thanks Big Clive!
Here's to ya!
Now sir – did the lithium battery go bang while you were overcharging it?