You will find all available batteries for your Giant E-Bike here
Giant Energy Pak Battery Refurbishment Service - Please Read Description | eBay
EnergyPak Battery Systems | Giant Bicycles Official site
Giant Battery | Rebuild Service – EBikeMarketplace
Mighty Max 6V 5AH SLA Replacement Battery Compatible with Giant YB645 - 16 Pack | eBay
26V 15Ah for Giant Twist Energy Set AE Advanced Electronics STORCK RADDAR Battery pack Li Ion E Bike electric bicycle|Replacement Batteries| - AliExpress
Energypak Plus range extender for 2020 bikes | Electric Bike Forums - Q&A, Help, Reviews and Maintenance