Powerbook G4 sleep time


I've got a 1.5 GHz, 12 inch powerbook G4, with 768 megs of RAM. My battery life is good, 3-4 hours under normal load, so I think my battery is OK. But, when it's in sleep mode it seems to drain about half a percentage point every hour from the battery, which seems like kind of a lot to me, although I have nothing really to compare it to. This would give me about 8 days worth of sleep, which is fine, but I've heard people say their powerbook could get almost 2 weeks of sleep time on one battery (although these might have been much older machines).

What's the normal battery drain in sleep mode?