Okay, I talked to a seller on Ebay, who sells a NDS lite battery with its casing removed and say that, it's 2in×1.25in×<.25in which comes out to ~ 50mm×32mm×<6.3mm I think this would be the best option, but I can't clarify, would anyone be able to? It's 3.7V and 2000 mAh, so in theory, it's perfect.