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  1.    #1  
    I've read in various places that the USB ports on a computer do not supply enough power to charge the touchpad.

    Indeed, when I plug it into my computer via USB cable, the battery icon does not show the indicator that it is charging.

    However, I see my battery level very slowly increasing. So does it actually charge..?!?!?!
    Last edited by manjazz123; 08/24/2011 at 03:39 PM.
  2. #2  
    Yes.

    I have it connected with just the USB cable, streaming music and the battery will go to 100%. Doing more, it may be a loosing battle to charge, have not stress tested it.
  3. JerkyChew's Avatar
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    #3  
    Mine behaved like the iPad - It only charged when the screen was turned off.

    EDIT: I should mention that some modern USB ports put out enough voltage (5v?) to charge the TouchPad. Usually it's only one port on the machine and it may have a special icon on it.
  4. #4  
    Voltage is not the issue, it's amperage. All USB ports provide 5V. Standard USB ports provide only 100 mA of current (0.1 amps), while high-power USB ports can provide up to 500 mA of current (0.5 amps). The Touchpad's wall charger outputs 2 amps.
    Touchscreens are a fad.
  5. #5  
    slooooooooow trickle charge at best if your not doing much on it at the time or th displays off.
  6. #6  
    is it ok to use an ipod wall charger?
  7. #7  
    iphone wall charger is 1A, it brings up a message saying "Your device is connected to a chargingsource that provides less than the recommended voltage or current. To reliably charge, use the power adapter and USB cable that came with your device."
  8. #8  
    Quote Originally Posted by Syndil View Post
    Voltage is not the issue, it's amperage. All USB ports provide 5V. Standard USB ports provide only 100 mA of current (0.1 amps), while high-power USB ports can provide up to 500 mA of current (0.5 amps). The Touchpad's wall charger outputs 2 amps.
    I'm sorry but I have to disagree about touchscreens being a fad. I remember all the blackberry fans saying when the iPhone came out they would never give up their blackberrys but most people I know either have or are considering it. And those windows 8 tablets coming out next year look pretty sweet. By the way I've had my tp for 2 weeks and I'm loving it. I rarely use my iPhone or PC anymore, though if webos no longer gets future support I'll buy an iPad or windows tablet.
  9. #9  
    Quote Originally Posted by sjp770 View Post
    is it ok to use an ipod wall charger?
    Quote Originally Posted by sjp770 View Post
    iphone wall charger is 1A, it brings up a message saying "Your device is connected to a chargingsource that provides less than the recommended voltage or current. To reliably charge, use the power adapter and USB cable that came with your device."
    There are two separate factors determining the TouchPad's ability to accept charge:

    1) The configuration of the Data+ and Data- lines in the Charger. The TouchPad will only charge if the Data lines are bridged and a potential divider applied giving the correct Voltage and Impedance

    2) The Charger's ability to supply the (up to) 2 Amps which the TouchPad will draw if it senses the correct configuration described in 1) above. Beware that frigging a cable to allow the TouchPad to draw its full current may overload an iPod Charger though an iPad charger is capable of delivering up to 2.1 Amps.

    Caveat: If you don't understand my ramblings, DON'T play with this!
  10. #10  
    From wikipedia on USB Power:

    PowerThe 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 3.0, the voltage supplied by low-powered hub ports is 4.45–5.25 V.[37]

    A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0; 6 (900 mA) in USB 3.0. There are two types of devices: low-power and high-power. A low-power device draws at most 1 unit load, with minimum operating voltage of 4.4 V in USB 2.0, and 4 V in USB 3.0. A high-power device draws the maximum number of unit loads permitted by the standard. Every device functions initially as low-power but the device may request high-power and will get it if the power is available on the providing bus.[38]

    Some devices, such as high-speed external disk drives, require more than 500 mA of current[39] and therefore cannot be powered from one USB 2.0 port. Such devices usually come with Y-shaped cable that has two USB connectors to be plugged into a computer. With such a cable, a device can draw power from two USB ports simultaneously.[40]

    A bus-powered hub initializes itself at 1 unit load and transitions to maximum unit loads after it completes hub configuration. Any device connected to the hub will draw 1 unit load regardless of the current draw of devices connected to other ports of the hub (i.e. one device connected on a four-port hub will draw only 1 unit load despite the fact that more unit loads are being supplied to the hub).[38]

    A self-powered hub will supply maximum supported unit loads to any device connected to it. In addition, the VBUS will present 1 unit load upstream for communication if parts of the Hub are powered down.[38]

    In Battery Charging Specification,[41] new powering modes are added to the USB specification. A host or hub Charging Downstream Port can supply a maximum of 1.5 A when communicating at low-bandwidth or full-bandwidth, a maximum of 900 mA when communicating at high-bandwidth, and as much current as the connector will safely handle when no communication is taking place; USB 2.0 standard-A connectors are rated at 1.5 A by default. A Dedicated Charging Port can supply a maximum of 1.8 A of current at 5.25 V. A portable device can draw up to 1.8 A from a Dedicated Charging Port. The Dedicated Charging Port shorts the D+ and D- pins with a resistance of at most 200 Ω. The short disables data transfer, but allows devices to detect the Dedicated Charging Port and allows very simple, high current chargers to be manufactured. The increased current (faster, 9 W charging) happens if both the host/hub and devices implement the new charging specification.


    The point being that you can get up to 500ma from a standard USB 2.0 port without special battery charging provisions and between 900ma and 1.8amps depending on the specific port options with battery charging spec enabled.

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