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Topic: Possible to draw constant 12V from a QuickCharge 2.0 Powerbank? (Read 1 time) previous topic - next topic

fasoha

Hello everyone!

I've built an Arduino inside of a RC-car and replaced its batteries (added up to 12V) with a Powerbank which has a 5V out which I use for the Arduino and a 12V QuickCharge 2.0 out which is meant to be for those Androids that have QuickCharge enabled. I connected the 12V out to the cars motor, and while it does work its substantially slower than with the batteries built in. I'm guessing the QuickCharge 2.0 stuff can only detect QuickCharge enabled devices and thus defaults to a 5V output? Is it possible to get a constant 12V output from that outlet of the powerbank?

septillion

Yes, that's what the Quick charge standard is all about. Would be a bit dangerous to have a USB port with 12V on it, wouldn't it?

Two options here
1) Mod the powerbank
2) You have to talk to the powerbank to convince it you're a quick charge enabled device so it will give you 12V.

Both are not the easiest thing to do.
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fasoha

The Powerbank came with a USB cable meant for the QuickCharge port, I've sliced it apart to connect it to my motor but to my surprise there are only 3 wires inside and they do not follow a color standard since they are white, blue and pink-ish. I'm taking the male usb adapter of this cable is what communicates the QuickCharge Standard to the powerbank, so would connecting these wires to the motor suffice? If so, which of these weird colours is power and ground? Google has failed me so far.

septillion

I'm taking the male usb adapter of this cable is what communicates the QuickCharge Standard to the powerbank
There you assume wrong. It's the device you connect to the powerbank via whatever cable. The USB cable is just a usb cable. Your not going to get 12V out of the powerbank by just connecting wires to it. You need a Quick charge capable device on the other end. You can try to fake the communication with the Arduino.

And are you 100% sure it only has 3 wires? Does the cable have by any change a sleeve around it?
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fasoha

This is the cable that came with the powerbank: http://i.imgur.com/6Z4mv9s.jpg.

What you said makes sense, I wrongly assumed it'd be the cable. Since the Arduino is connected to a different output (5V), how could I use that to fake a 12V requirement from the QuickCharge port?

I was hoping that there'd be some kind of adapter or microcontroller that would be QuickCharge enabled and thus draw all the power I need.

MarkT

3 wire + shield = 4 wires perhaps?  Multimeter time.
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septillion

Code: [Select]
If you see the pink-ish cable just as a faded red cable it's just the USB colors. And indeed I think the sleeve is the GND :)

But no, the whole power of Quick Charge and USB3.0 Power Delivery is that it's fully backwards compatible with ordinary (5V) USB and you have no change of accidentally connecting 12V to your precious new Google Pixel even though (at both ends of that cable) it's just USB connectors. Because that would really ruin your day ;)


[quote author=fasoha link=msg=3072535 date=1483732539]
how could I use that to fake a 12V requirement from the QuickCharge port?

Connect the data cables of the Quick Charge port to the Arduino as well. But I have no idea what kind of signals the powerbank expects from the phone... But I have seen China / DIY Quick Charge tester so it is possible to fake a Quick Charge device :)
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mbull

I realize that this conversation is a few months old, but I wanted to add some info.

You can see how the QC handshake works on sheet 9 (page 10 in your PDF reader) of the Quick Charge patent. Here is the PDF.


You could program an arduino to do the voltage negotiations. Someone else did this by physically modifying a digispark and flashing the microcontroller. He documented this in a blog post.


However, in your particular application using the power bank may not be the best solution. You need to take into consideration how much current your power bank is rated for at 12V. The most I have seen is 1.5 amps.

Another thing to consider is although a power bank may have a higher capacity than a similarly sized LiPo battery, you will chew through its capacity much faster. This is because power banks generally have all of their lithium cells connected in parallel, so internally it has a nominal voltage of around 3.7V. This then gets fed through a boost converter in order to raise the voltage to the 5, 9, or 12 volts. LiPo cells that have a nominal voltage of 11.4V have three cells wired in series to get the desired voltage.

septillion

About the capacity, that's kind of true. That's because the capacity of most powerbanks is displayed in mAh which is a stupid unit... Because to know the amount of power that adds up to you need to know the voltage as well. A better unit would be mWh of just Wh. Then you can see that 10Wh @ 5V 1A (= 5W) can give you 2 hours of runtime and just under 1 hour for 12V 1A (= 12W). And that's not even counting the losses but for both 5V and 12V the voltages needs boosting = extra losses.

And yeah, the handshake is what I suggested but it's not as easy as plugging it in :)
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jremington

Rather than hack a poorly understood commercial product, I would use a boost converter with a conventional battery.

That way you know exactly what you have in terms of battery capacity, power and overall efficiency.

Pololu has a great selection of reasonably priced boost converters.

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