Lego Power Functions Technics: Battery Case - Ref 59510 - Electric 9V | eBay
LEGO® Power Functions Battery Box 8881 | Other | Buy online at the Official LEGO® Shop US
DooQi CADA Technik Power Function Kit for Technical Cars, Including 3 Motors, LEDs, Battery Box and 2.4 Ghz Remote Control (Compatible with Many Models Such As Lego CADA) (S059-001)
LiPo Added To LEGO Power Functions Power Brick | Hackaday
Using LiPo Batteries with LEGO® Trains — Monty's Trains
Alternative LEGO Rechargeable Battery Box (8878) – Green Gecko Workshop