Originally Posted by agentdr8
It charges via USB, but slowly. The OEM 2A charger has different voltages on the data lines that tell the tab to initiate a fast charge at a higher current draw. This is similar to how the iPad chargers work, and why building the usb adapter in this thread helps when charging via non OEM chargers (including USB ports).
Reminds me about hd2 kernel developpement discussion: like on our tabs, i think the kernel was responsible for choosing charging rate, because some kernels with bugs were keeping slow charge mode whatever the supply was.
On non buggy kernels, it seems the trigger was connection of data lines: a computer does connect data lines -> slow charge, a wall charger does not -> fast charge.
As soon as will have custom kernels for our tabs, we'll be able to change the charge mode that the tab choose. Some computer have powerfull usb power line. However some low quality usb car power adapter could get destroyed if our tab use fast charge mode for too long.