Battery life FACTS:
New 3DS XL – 5 hours 45 minutes
New 3DS – 5 hours 23 minutes
3DS XL – 5 hours 01 minutes
2DS – 4 hours 36 minutes
3DS – 4 hours 05 minute
http://www.forbes.com/sites/andyrobertson/2015/01/23/new-3ds-battery-test/
DS battery life.
First Brightness - 6 hours, 19 minutes
Third Brightness - 4 hours, 15 minutes
Fifth Brightness - 3 hours, 30 minutes
http://www.nintendoworldreport.com/feature/26166/3ds-battery-tests