Nintendo Power Adapter
For basic charging, use the original power adapter supplied by Nintendo in the box for the DSi or a spare power adapters produced by Nintendo. They are relatively inexpensive ($5 to $10 as of publication). You can buy cheap third-party adapters, but it's safer to stick with original manufacturer's equipment or a brand you trust. If you travel a lot with your DSi, you may wish to carry a spare charger. You can play while charging, but it will charge faster if you don't.
Car Power Adapter
When you're on the road a lot, it's good to have a car power adapter for your DSi. The DSi can charge while you drive, and other occupants of the vehicle can play the DSi while it's charging. Look for a Nintendo-branded car power adapter or buy an adapter that is part of one of Nintendo's packaged kits that may also include a carrying case, screen protectors, extra styluses or game cases.
Docking Station or Cradle
A docking station provides a simple, organized way to charge your DSi. The docking station holds it securely rather than having it set on a desk or table while plugged into a power outlet. Docking stations may charge a single DSi or a DSi in combination with other devices, such as the DS-Lite or Nintendo Wii remotes. The docking stations are available in a variety of prices, depending on functions, but look for brands you know and research the products.
Portable Electricity Sources
A power inverter, when connected to a vehicle's 12-volt power adapter, allows you to plug in your Nintendo DSi and other devices, such as laptops and cell phones, that are powered by or charged with electricity. Another source of portable electricity is a battery pack that charges in a standard wall outlet to deliver a few hours of electrical power at a later time.