LG Muziq data cable question
In these instances, the device is generally not actually GAINING a charge, since it is using power to stay on, but its more like it is replenishing power used, and so the battery level should stay stable.
With all that said, I have no idea if your will do that or not. the only way to test it, I suppose, would be to leave it on and plugged in for over a week, unless of course you can find some sort of LG documentation that says it will trickle-charge.
Otherwise, assume that it wont, and move on.