I'm a bit overwhelmed. 7th Gen iPod classic 800GB, iFlash Quad, 3000mAh Battery and Rockbox. I'm afraid to close it : r/ipod
3rd party extended Battery guide – iFlash.xyz
iPod Classic 5th Gen battery options | MacRumors Forums
iPod Classicに大容量ストレージとバッテリーを搭載してみた : Eleclog.
Portable Battery Charger Backup Adapter Power Bank Compatible With Ipod Video Photo Nano 6th Gen 4th Gen 3rd Gen 2nd Gen 1st Gen Mini Classic, iPhone 4S 4 3GS 3G 2G, iPad
Video (5th) 30GB用(1900mAh)バッテリー - ipod iphone parts shop