Steve Smith explains how-to charge your favorite USB devices faster and more efficiently.
Episode #4-45 released on July 31, 2014
We all charge devices, most of us have computers, and many of us plug are mobile devices into our computers. The question is which is faster, plugging our gadgets into our computer, or into the wall adapter that came with the mobile device.
The issue comes down to a very simple set of parameters that we rarely think of or realize. A computer has a maximum amount of power it is willing to provide USB which is usually 5V, but can be as low as 4.75V or as high as 5.25V. Converted into what most are used to hearing, it means that the USB circuit itself has access to 500 mA, but no more than 100mA is available per USB port. Now, most USB ports on computers are paired into sets of two, and each circuit contains no more than 5 USB ports, which explains why only 100 mA is available per port. But, the fact of the matter is, the hubs and ports will not deliver more by design.
This means your USB is giving your device about 0.1A of charge. Now, various chargers will provide more of a charge. For example, some tablet chargers provide 0.3A, or 300mA of a charger, which will allow the device to be charged in 1/3 the time in theory. The iPhone 5 charger yields 0.15A, or 150mA, which is 50% more power than a computer.
The length of the USB cable does have a reasonable amount of relevance to the amount of power being transferred. The cable is usually between 20 and 28 AWG, and that means it can have a resistance of 0.2 to 1.3 ohms. If the cable was 30 cm, it will transfer roughly 10 times more power than a 3M cable.
Now, this means that if you want to charge your device faster, considering using a wall charger with a short cable. Your device will charge upwards of 50% faster, maybe more. Using a longer cable means you will run the risk of having a weaker charge and signal, it will cause the charging process to take longer, hence why most cables supplied are almost the same length.
Host : Steve Smith | Music : Jonny Lee Hart | Editor : Steve Smith | Producer : Zed Axis Productions