Ok now some the threads are old and some things no longer sold. Qusetion is where are you buying from and what kind? So many to choose from!
There are “two main camps” Those who build their own batteries from individual cells and those who buy prebuilt LiPo packs (and those still running sealed lead acid batteries but that is less common) Not sure where to buy individual cells. The ones Ive seen are crazy expensive for the number of cells needed vs a premade pack. I buy premade 3S 5000mAh LiPo soft packs from Amazon. Typically the GoldBat brand.