>>33488660The DSTwo has an onboard CPU that it uses for GBA emulation, real-time saves and other stuff. Problem is, when you insert it on a 3DS the system will constantly send power to the cart to power that CPU, even when it's not in use. This makes the battery consumption skyrocket just from having it inserted in your system, even in sleep mode, even when playing (digital) 3DS games.
You can test this out yourself using your Acekard or simply having a game cart inserted instead of the DSTwo.
