"09" 420 battery problems already?

Anyone else that has the AT + EPS system having trouble with the shifter because of a low battery level? Took mine to dealer service ( under warranty) and was told I'd need to charge battery after riding. Using a pro. charger, to get it up to 20 amps in order to work the auto shift. This is a new bike with 300 miles. Do these batterys have a warrenty? Why can't the alt. keep up?