While Nintendo is yet to release concrete figures on the battery usage of the 3DS - not that you can ever trust official figures - company president Satoru Iwata has hinted that it won't last as long as the DS. "As for the battery, it is inevitable that Nintendo 3DS will be a device which requires more frequent recharging than Nintendo DS" Iwata said during a recent Q&A session with investors. "This is why we are going to include the cradle, which is a dedicated battery charger. Perhaps we may need to dispatch to our consumers a message, something like, 'Please place your Nintendo 3DS on the cradle as soon as you return home with it'."
That first sentence is the key: it means you won't get the same battery mileage from the 3DS you do from a DS. It's not a surprise, of course; extra horsepower and 3D capabilities will drain a battery faster than a DS game would, and packing one in that could withstand a lot of 3D play would have driven the cost of the handheld to a point Nintendo normally doesn't sell hardware.