Hello -- Have you changed the HardDrive? I think that the 7200/rpm drives will drain the battery
faster -- is this the case?
Not to complain, but I also just got two of these batteries but cannot get more than about 3 hours out of them. They charged for at least 8 hours and have been completely drained, by playing music, three times so far but 3 hours is the max for both (in two separate N IIs.) ... and this is just playing an album, navigating to another and playing it, etc. ... no fast fwd'ing or other use of functions.
How do you manage to even approach 10 hours battery life with them?