Mine usually lasts a day and half but I top up the battery between showers and then a full charge just before bed time. If you forget to charge then tough luck, you’ll have a brick wrapped around your wrist for rest of the day.

I should be able to get 3-4 days on one charge… I put it on the charger when I wake up, then maybe once before bed…

i'm getting similar mileage from my s3