675 zinc-air batteries run a UP hearing aid for an impressively long time. Days to weeks, depending on age of the battery and how much use it see. I'm surprised

675 zinc-air batteries run a UP hearing aid for an impressively long time. Days to weeks, depending on age of the battery and how much use it see. I'm surprised the chemistry doesn't see much use outside of hearing aids. For something where long downtime is undesirable, replaceable batteries are a lot nicer than rechargeable.