The only thing that I see that I could add to Tony's post (wtg, tony) is this:
the "battery" light that you are seeing.. could it possibly be the coolant light? it is OFTEN mistaken for such. Yellow "barrel" shaped icon with an X in it?
The reason I ask is because a "battery" light (system charge indicator) would usually be an alternator charge problem, and would be much more rev dependant, and not time dependant (10 minutes on, 10 off, etc, like you said)
If it is the coolant light, its finicky from the factory, top to 1/2 inch above the MAX line when cold for a simple fix.
