To reinforce the three respondants, and to put a slightly different twist on the words -
When you accomplish a battery start, the aircraft is basically in the Emergency Power condition. The 'default' idle position is flight idle, that taken up in an emergency power situation. Electrical power is not available from the Battery buses to Engine Idle control. The various 'luxuries', like hot coffee, landing lights, and Ground Idle become available when normal AC power, and DC power from the TRUs becomes available.