Why do I get such wildly different charge currents into my tablet (Galaxy Tab Pro), depending which similar USB cable I choose?
The most extreme example is one that only allows .28A to charge my tired tablet whether the cord is plugged into a wall wart, fast charger, or basic linear 5 power supply. That same cord will pass 2.4A @ 4.9V from the fast charger into a resistor.
I gathered up all the USB charging cords I could find at home (8) and tested the current thru each when charging the tablet. Most passed a fraction of an Amp but 2 allowed nearly 2A.
I assume the tablet adjusts charge rate depending on something (I don't know what), so I repeated the test into a 20W rheostat, increasing the load until the volts drooped to 4.9V on each. On this test most of the same "wimpy" cords could pass over 2A.
What explains this difference in similar length USB-to-micro USB cords?
I started this test because my tablet wasn't 100% after an overnight charge.
The most extreme example is one that only allows .28A to charge my tired tablet whether the cord is plugged into a wall wart, fast charger, or basic linear 5 power supply. That same cord will pass 2.4A @ 4.9V from the fast charger into a resistor.
I gathered up all the USB charging cords I could find at home (8) and tested the current thru each when charging the tablet. Most passed a fraction of an Amp but 2 allowed nearly 2A.
I assume the tablet adjusts charge rate depending on something (I don't know what), so I repeated the test into a 20W rheostat, increasing the load until the volts drooped to 4.9V on each. On this test most of the same "wimpy" cords could pass over 2A.
What explains this difference in similar length USB-to-micro USB cords?
I started this test because my tablet wasn't 100% after an overnight charge.
