Did you buy just your V8 body, because the kit comes with 2 batteries and the charger. I too have a huge amount of different batteries and chargers... gets a bit much lol. Just be careful and take the advice given. Don't use mismatched batteries and/ or of different age. Even if one has a lot of ( identical) batteries for changing out for one device, the should only be used in the same pairs and should be labeled 1A, 1B, 2A, 2B, 3A, 3B. Only the 1s should be used together and only the 2s etc. They should be alternated in how you place them in the device. If one battery in a set goes bad, never use the ( OK) partner in a new set. It can be used in a single battery device, but not paired with another.
I am no battery expert AT ALL! This is just battery stacking safety rules I have read here on the forum.