The Nintendo DSi uses a rechargeable Lithium-Ion battery (model TWL-003 for DSi, UTL-003 for DSi XL) with a standard voltage of 3.7V and typical capacities around 840mAh to 900mAh, though higher-capacity third-party replacements exist; it's designed for easy user replacement by unscrewing the back cover and swapping out the old pack for a new one to restore gaming time
