Not sure how big the battery pack is, but I have the Nintendo Hybrid case over my switch which makes the Switch a bit thicker. So I use this case also and fits my Switch with Hybrid case and plenty of room for everything else! The only problem I have is the Velcro that holds down the Switch does not actually hold the Switch down. It's not really an issue for me. [Updated] ButterFox Nintendo Switch Hard Carrying Case with 19 Game Cartridge and 2 Micro SD Card Holders - Red/Black