If you are a bit disappointed with the 3-8 hour battery life for the 3DS, accessory manufacturer Nyko has a battery pack called the Power Pak+, an add-on device that promises to double the interval between 3DS battery charging. Nyko is known for making many third-party charging stations and game controllers for the current game consoles.
The Power Pak+ is a high capacity battery that hooks onto the back of the 3DS, adding extra power at the cost of added bulk. They say the device will double the battery life of the 3DS effectively transforming three to eight hours into up to a maximum 16 hours. The picture shown here is the Power Pak+ attached to the 3Ds and will come with a special tool to unscrew the back of the 3DS to change out the battery. This battery will retail $19.99 USD.
But if you are patient and wait another week, Nyko is releasing a charger base packed along with one of the Power Pak+ units. The charge base will allow players to drop their 3DS unit inside for a little charging up while not in play. The base and Power Pak+ combo is only $29.99 USD, and it might be worth waiting a week to get both.