6V 4.5AH Lithium Iron Phosphate battery packs, direct replacement for sealed lead acid batteries, LiFePO4 Chargers.
Amazon.com: Duracell 245 6V Lithium Battery, 1 Count Pack, 245 6 Volt High Power Lithium Battery, Long-Lasting for Video and Photo Cameras, Lighting Equipment, and More
Duracell PX28L 6 Volt Lithium Battery, Carded – Batteries and Butter