The answer to that question is, Yes, the battery life is shortened when I m using it to listen to MP3s.
Batteries are relatively cheap, and there are a lot of good rechargeables on the market.
I would recommend investing in a couple of pairs of NiMH rechargeable batteries, I ve got a couple of my friends to switch to them, and they really love the convenience. The MiniJam seemed to draw considerably more juice from my batteries than the SoundsGood player did. I used the units when waiting for meetings or when I had a short amount of time to kill. Whereas the SoundsGood player barely affected the battery life, the MiniJam seemed to shorten the expected lifespan of a set of batteries considerably. No, I think that the battery life for the MiniJam is acceptable.