radicchio
Well-known member
The latter. For the phone to enter Fast Charge mode it has to detect that the port isn't a USB data port. Most chargers short the data pins internally so you can use any USB cable. Perhaps the charger you're trying to use doesn't do this, in which case you will need a 'charge only' USB cable.
A couple years ago, when i got my Android tablet, I did some reading about chargers and cables, etc. The consensus I found at the time was that using a charge only cable, versus charge/data cable, would result in a quicker, more efficient charge I found it was a little hard to find the charge only cables, but with some persistent searching on Amazon I did find some. That's all I've used on my tablet, so I don't know if it really makes a difference, but it might be worth considering. By the way, I make sure to label my charging cables so that I don't try to transfer data with one of them.