Nintendo just restocked official 3DS battery packs, if you need them : r/ nintendo
AKKU 30619: Battery for Nintendo 3DS XL, Li-Ion, 1300 mAh at reichelt elektronik
New Original Official OEM Nintendo 3DS Battery Replacement CTR-003 1300mAh 5Wh 889231988178 | eBay
5000mAh Extended Battery for Nintendo 3DS – Press Any Key
Amazon.com: Pickle Power 3DS Battery, 1350mAh CTR-003 Battery for Nintendo 3DS, 2DS XL, 2DS Game Console with Tool Kit (Not for New 3DS and 3DS XL) : Video Games
3DS Battery Pack (Nintendo 3DS) – J2Games
Fix Nintendo 3DS Battery Woes With Nyko's Power Pak + | WIRED
Μπαταρία Nintendo 3DS - 2DS CTR-003 3.7v 2000mAh - modchip.gr
Official Original Nintendo 3DS CTR-003 Rechargeable Battery - Walmart.com
2x Replacement Battery for Nintendo Switch Pro Controller 3DS 2DS 2DS XL CTR-003 - The ICT University