My wife inadvertantly left the dome light on on our '03 Echo in the summer when the car was only a year old. The car wouldn't start the next morning...completely dead. Her father had a brand new battery, never used, and that new battery would no longer hold a charge. I learned a lesson then not to let a battery go dead even if it's new as it was useless after a couple of years sitting idle. Most know about that probably, but this warning is for those that don't.