What is the life of a cordless vacuum battery?

Hello Summer. I expected an answer from a Dyson affiliate to that effect. While I understand that there are varying factors, there must be an average based upon empirical data. These batteries are very expensive not to mention bad for the environment. I went ahead and purchased the vacuum much against my better judgment because it is for my mother who needs the flexibility of cordless. She has a small apartment with no extreme temps, hard weather, etc… I’m quite perplexed, I must say, as to how the various tools could possibly degrade the battery. I just pray it holds up.