I just put in a new battery and charged it. The acpi info (which is correctly displayed by the power applet compared with /proc/acpi/battery is:
Acpi Data Design Capacity - 84.2 Current Charge - 88.0 Last Full Charge - 88.5
Now this looks pretty good to me - I have charged it to just over the design capacity and it is at present fully charged:
The power applet however has other (odd) ideas and interprets this data as follows:
Applet Interpretation Percent Charged - 99.5 Capacity - 0.3% (poor)
Huh?