Impossible to specifically answer. It all depends on how often, how long, and how much or how little the player is used.
3 hours and 56 minutes =]
It is no so much the brand as the chemistry. A lithium ion cell will have a long shelf life and a great power to weight ratio.
44hours and 11minutes
They last about 4 hours but depending on the size. If litholeom then much longer like maybe 7-8 hours. But if rechargeable then about 3 hours. Battery life is dependant on use - the more you use it...
half a secound