The K1 only charges through the propietary connector. You need 12V through pins 1 & I believe pin 34 of the connector (if you look at the graphic of the stock charger, it shows what pins.
The USB connector are pinned on 21, 23, and 24 (not sure of 4th pin).
If you shove 12V through the USB conector, you will not only NOT charge the K1 (since the it is not connected to the power pins, but will likely fry the circuits.
There is NO WAY to charge the K1 with 5V as the battery (an L10M2121) has a base voltage of 7.4V @ 3.5 Ah (3550 milliamp).
Many large tabs use 7.4V batteries and are not chargeable with usb (Iconia, for example) - though not all.
Even many small tabs (Kindle Fire, etc) , although charge with 5V, would take forever to charge at the standard usb spec 1/2 amp. When the small tabs are chargeable through USB, they usually still have a charger that pushes 1 to 2 amps (Kindle Fire's charger is 1.5amp) because the batteries are almost always 3500 milliamp or higher. This is accomplished by tying the D+ and D- pins together to notify the client to go into "charging" mode."
