It's all about what you play, how loud you play it, what setting you have the backlight set to, and if you're using VIDEO.
Set your backlight settings to lowest, Make sure the auto-off feature (for the backlight) is set to the minimum you're comfortable with (5 sec for me), and that the wifi is turned off. This alone will extend your battery life considerably!
Also, like Oban mentioned, if you're watching videos, it eats up up batteries like nobody's buisness! I get about...say...4 hours out of my ZUNE 30 when watching Video.
The batteries on these things are fairly universal, so I'm willing to bet you should have no trouble with the hints we've given you here.
As far as your charge cable is concerned: Does it fit? Try plugging it in (while not plugged into an outlet!) to make sure it's the same cable. If that is the case, and your cable fits, check MS documentation on
www.ZUNE.net to be sure that it's compatible. I believe these cables are nigh-universal, so it shouldn't be an issue. Kjkolko? Thoughts?
BTW, be sure to bring this up on the first zuneusers podcast!