Results 1 to 5 of 5
  1.    #1  
    ******This is still experimental. I am not responsible if you break your phone or computer.******

    I was thinking about this the other night and fabbed up a quick cable and the pre was indeed able to charge at 1A. I got the idea from some portable hard drives that use 2 usb drives for additional power.

    1. Get yourself a spare USB A(computer side) to micro usb B(phone side) cable. Monoprice is a good cheap place.
    2. You will also need some other cable that has a standard USB A(computer side) connector on it. Please make sure it is nothing you want to use in the future because we will be breaking it.
    3. Cut both cables off about 6 inches away from the USB A side.
    4. We want to keep both of the USB A sides and the micro usb side.
    5. Strip all three down to where you can see the inner wires. They should be black, red, white and green.
    6. On both of the USB A sides we want to strip the ends of the red and black wires. The green and white wires on these ends should just be taped down.
    7. On the micro usb side, strip the ends of all 4 wires.
    8. On the micro usb side, splice the green and white wire. It would be best to use solder if you have it and know how.
    9. Now you need to splice all 3 red wires together and then all three black wires together. As said before, it is best to use solder.
    10. Tape everything up to make sure the black and red wires do not touch and nothing is exposed.

    This should allow you to connect your phone to 2 usb ports to draw 500mA each which gives you 1A. This will no longer work for a data cable due to the white/green wire connection. This was required for the phone to see it as a fast charging cable. Hope this makes sense without pictures. I have not tried it with a touchstone yet but it is possible it will work. Try at your own risk.

    Thanks,
    Eric
  2. #2  
    Are you sure to splice the green and white from the micro usb?
    I have reason to doubt you, I have just always assumed when making charging cords like this, the wires are capped with tape and left separate.

    I would be a little concerned that the computer would not be putting out consistent 5V which would cause problems. I know I am already taxing my 550W PS, so I will stick to the wall plug.

    Great idea though.
  3.    #3  
    yes I am sure that you splice those 2 wires. It is part of the USB charging standard. Here is a wiki article stating that the standard shorts the D+ and D- pins.
    Universal Serial Bus - Wikipedia, the free encyclopedia

    Also, I wouldn't worry about taxing your power supply. Using Ohm's law and the power law P = I x E where P=power(watts), I=current(amps), E=voltage, you then get P = 1 x 5, P=5 Watts. Not a big deal in the grand scheme of things. I have tried this on my phone and haven't fried it. Also, the USB specs on power are below. So you needn't worry about the 5V output.

    "The USB 1.x and 2.0 specifications provide a 5 V supply on a single wire from which connected USB devices may draw power. The specification provides for no more than 5.25 V and no less than 4.75 V (5 Vą5%) between the positive and negative bus power lines. For USB 2.0 the voltage supplied by low-powered hub ports is 4.4 V to 5.25 V.[26]"



    Quote Originally Posted by dfroelich View Post
    Are you sure to splice the green and white from the micro usb?
    I have reason to doubt you, I have just always assumed when making charging cords like this, the wires are capped with tape and left separate.

    I would be a little concerned that the computer would not be putting out consistent 5V which would cause problems. I know I am already taxing my 550W PS, so I will stick to the wall plug.

    Great idea though.
  4. #4  
    As you said, this is the way that some external harddisk get some extra power, so no reason why it wouldn't work. Thanks for the description.
  5. #5  
    This should work fine. Connecting the data wires together is indeed correct, it signals the phone that it is not connected to a computer but rather to a 1-amp capable charger. I did the same when I created an 'emergency' charging pack using 3 AA batteries (I used 3 batteries partly because I had a 3-battery case on hand, and partly because I decided I'd rather use Alkaline batteries. For NiMh batteries you'd definitely need 4 batteries)

    One WARNING should be noted: make sure you connect BOTH USB plugs to the computer BEFORE connecting to the phone. If you connect the phone first, it will immediately try to draw at full current before you get the second USB plug in which may trip the current limiter on the port. Some USB ports have a tiny SMT fuse, and if you blow it that port will never provide power again (I think most USB ports use a solid-state current limiter that will recover, but the fused ones do exist).

Tags for this Thread

Posting Permissions