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  1. #1
    Senior Member
    Join Date
    Sep 2011

    LG V20 ASUS Fonepad 8

    USB charging problem my finding

    Hi there,

    I think this is one of the most annoying problem with all USB charging phones and tablets, and not only with Android.

    The first phone I've this problem is the Motorola E680i which is a Linux phone, it can charge via PC no problem, but only when the battery did not run down completely, or the phone will not charge with USB. I think this is due to the charging is controlled by the phone CPU, when the battery is run down the CPU won't work so no charging, that's why the package comes with an external battery dock charge !

    The next phone I've is the Nokia N900, it will only charge with a standard USB cable if the phone suite is installed on the PC, and I can't charge it with an external battery, I need a speical modified non standard cable to do it. There is something special with the cable that, with one pin 'pull down' with a resistor, to provide a false signal to the PC, to allow the USB to output full current, instead of treating the phone as an external storage or communication device, because of that the cable can not be used for normal USB connection. But strange is that, I can charge the phone on a Linux PC, without running the phone suite, with a standard cable, so obviously the charging is controlled by s/w, so it is not the USB output level prevented the charging as most people thought ! even the output is low the charging should still work, only take longer time. Beside that, AFAIK Nokia requires a slightly higher voltage to charge than other phones, there is an USB voltage booster specially designed for Nokia for this purpose.

    Now I turned to Android, I use HTC and Motorola, they are quite different beasts. HTC seems to work with any USB charging without problem, but Motorola is quite picky. During installation of winodws I plug in the phone and it charges, but when windows is half done the charging stopped, not completely stopped but tickle charge I guess, the 'lighting' is gone on the battery icon, but the display still say 'charging'. This charging takes forever to finish, it just can't get enough to cover the power loss in standby mode, so this is no use at all ! even worst, the 'charge only' option has been removed from the Razr on the ICS, to further limit the USB charging. This caused serious problem when I've other USB device in use on the computer, such as when booting Linux via USB flash while charging the phone, the boot will crash in middle due to the Razr becomes an USB flash and confuse the system. I also read about the problem the Razr won't charge when the battery completely run down, there is a video on 'the tube' about how to break open the chasis to manaully charge the battery !

    I just purchased a Samsung tab, it works like the Razr also won't charge via standard USB and external battery, there is a special cable and adapter to enable USB charging, I don't know it is designed in such a way so inconvenient to users. HTC is so far the most USB friendly phone I have used, although it fall short in other area.
    Last edited by joboy; 11-19-2012 at 11:55 PM. Reason: Update

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