Many of the pads that charge from USB can only take a little less than the 500mA the USB port can supply. Some makers get around that with "tricks" but nothing sounds wrong here.
Bob
I have a Flytouch 8 Superpad VIII and it is taking 1 hour to charge an additional 4% charge, hence it would take 25 hours to charge it from 0% to 100%. Is this normal for this android tablet or could it possibly be faulty?

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