Happy Energizer/XPal XP8000 user here. (8000mAh, not much bigger than N900, also can charge my laptop and my netbook) It requires a custom cable to charge, like most non-nokia chargers. I have the Brando USB adapter with charge/data switch, which works great for that ! That won't charge your N900. It's a 12V battery, not a 5V power pack.