1- might make the (waterproof) case harder to build 2- finding the right dead battery among 18650 batteries is requiring more hints than just "something is wron

1- might make the (waterproof) case harder to build 2- finding the right dead battery among 18650 batteries is requiring more hints than just "something is wrong" 3- marketing / convenience and probably you can order your dead battery straight from the app 4- monitoring battery charge, battery life / cycles / etc. 5- no idea :-) Just speculating, but I guess there are a lot of reasons why a bluetooth app makes sense