My Macbook will just Die when its on battery, yet the battery guage can be reading anywhere between 20 - 70%. Cocanut battery says my battery health is 82%, my mac is 24months old and the battery has gone though 185 loadcycles. Im guessing the battery is worn out but on most pc laptops when that happens the charge will just Drop suddently to zero. In my case the mac will power off (and die almost instantly if you try and power it on) but the battery guage will still try and tell me it's got plenty of charge left (if it gets that far into loading) as will the Leds on the battery itself indicating it does indeed have a charge. Did try an SMC reset by following the proccedure listed on the apple site but it didn't seem to make a difference. If the battery is worn out then fair enough but I was wandering if it was likely to be something else given that cocanut thinks the battery has around 82% of its design capacity. Macbook will run fine on the AC adaptor. It's the 1.83ghz core duo with 2gb ram and a 120gb HDD installed, combi-drive.