As you can see, it has a weird and old power cable, and instead of spending money to buy a compatible output cable, I decided to use what I had.
What I first did was to connect some lipo batteries and supply power to the board by touching the poles, and it worked. Then I thought batteries would be a bad way of doing this as they would constantly need recharging, so I decided to supply power from an outlet. I found a phone charger of exactly as many volts as required, and then did some soldering on a USB cable to make it a power cable:
However, when I plugged the charger and the cable, and then touched the jumpers' tips to the corresponding poles, the led board didn't light up. However, when I tried to power an Arduino with it, it worked, which means the cable is working perfectly fine. I tried a different phone charger, the same result.
So, how do I make the led board draw current from the phone charger?
Even low end USB phone chargers give you 500mA - you'd have to dig to find one that didn't.
What voltage is the LED bar supposed to run on? Hopefully 5v if you're powering it from a USB phone charger. But then how did you power it from a LiPo battery? That LiPo would only get you 3.7~4.2v, unless you mean a power bank (LiPo battery plus USB charging, and 5v USB output generated with a boost converter, commonly used as portable phone chargers).
Do you have the polarity right?
Are you sure you're making a good connection?
Does it still work with the LiPo battery like you tested before? (sanity check)
You've checked that the switch is in the on position, right? (we've all done it )
I connected three lipo batteries directly, so that I get 11.1 - 12 volts. The led bar works with that, but it doesn't work with a phone charger of 12 volts and 2.1 amps.
Do I need a charger that can supply more current to the bar?
(Also, the Arduino did fully work and the reason I can't tell you much about the led bar is that I took it out from an old bed and no one left any data for me. I found the voltage by powering it with different amount of 3.7 lipo batteries.)
If you have a multi meter, or similar, you could measure the voltage and current when the batteries are connected, and when the charger is connected. Some 'intelligent' chargers, at least ones I know of for cameras, etc. will switch off if they detect something connected that it doesn't expect. For camera batteries, and some power tools, there is a third connection for communication between battery and charger. It may be, that your charger detects the inrush current when the led's are connected, or if an oem charger expecting some signalling back from the phone via usb connector.
Where did you find a 12v phone charger? I see a usb plug at the other end. USB is 5v, and a phone charger with a usb outlet is going to put out 5v. Systems like QC2 and 3 can output 9 or 12v, but only after negotiating with the connected device over the data lines, otherwise they just put out 5v (otherwise they would blow up any non-QC usb device plugged into them)
DrAzzy:
Where did you find a 12v phone charger? I see a usb plug at the other end. USB is 5v, and a phone charger with a usb outlet is going to put out 5v. Systems like QC2 and 3 can output 9 or 12v, but only after negotiating with the connected device over the data lines, otherwise they just put out 5v (otherwise they would blow up any non-QC usb device plugged into them)
I used to work for an electronics retailer that bought all their stock straight from the warehouse in China, and the purchasing department was more focused on buying the cheapest equipment rather than the best equipment. This resulted in us setting a 5W UHF CB radio which had a 12V charger (at about 1A) that had a USB plug. That would have been exciting if someone plugged into their phone, although fortunately it was a min-USB plug.
So basically, a USB cable comes with a built-in 5 volt regulator? It makes no sense. If I give 12v through the power pin, I should get 12v at the other side.
So basically, a USB cable comes with a built-in 5 volt regulator?
Not sure what you are referring to. I have, like BJHenry mentioned, equipment with standard usb connectors, for power, but they need 12V power. In fact, the whole situation wrt usb connector types was screwed up as soon as the specification was released.
Aorda:
I connected three lipo batteries directly, so that I get 11.1 - 12 volts. The led bar works with that, but it doesn't work with a phone charger of 12 volts and 2.1 amps.
USB chargers use 5V. Well some may negotiate higher currents and voltages over the USB data lines, but by default you'll not get 12V, as that would destroy any non-12V device.
DrAzzy:
Where did you find a 12v phone charger? I see a USB plug at the other end. USB is 5v, and a phone charger with a USB outlet is going to put out 5v. Systems like QC2 and 3 can output 9 or 12v, but only after negotiating with the connected device over the data lines, otherwise, they just put out 5v (otherwise they would blow up any non-QC USB device plugged into them)
Also, the 12-volt phone charger is a Samsung fast charger. I suppose there is also a software part for drawing that much electricity, I guess that's why the LED bar didn't work.
I eventually gave up and just started using three lipo batteries. It has been months and they still haven't run out.
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