iBook G4 Battery Problem

I got a new battery for my 12" iBook G4 a couple of years ago and it worked perfectly. Then, a couple of months ago, I turned off my computer when the battery was at 23% and when I turned it back on, the battery refused to charge above 23%. I've left the computer plugged in (but turned off) and the battery didn't charge. This week, I tried leaving the computer plugged in and turned on for 10 days, and the battery charge indicator has slowly crept up to 28%. When I have the AC adapter plugged in, the ring is always green and the message in the battery indicator reads "Battery is not charging."

I tried resetting the PMU but that didn't help.

Does anybody have suggestions for what might be wrong?

Here is my system power settings information:

Battery Information:

Charge Information:

Charge remaining (mAh): 1055

Charging: No

Full charge capacity (mAh): 3805

Health Information:

Cycle count: 93

Condition: Good

Battery Installed: Yes

Amperage (mA): 0

Voltage (mV): 11630

System Power Settings:

AC Power:

System Sleep Timer (Minutes): 60

Disk Sleep Timer (Minutes): 10

Display Sleep Timer (Minutes): 15

Dynamic Power Step: Yes

Reduce Processor Speed: No

Automatic Restart On Power Loss: No

Wake On AC Change: No

Wake On Clamshell Open: Yes

Wake On LAN: Yes

Wake On Modem Ring: Yes

Display Sleep Uses Dim: Yes

Battery Power:

System Sleep Timer (Minutes): 5

Disk Sleep Timer (Minutes): 10

Display Sleep Timer (Minutes): 1

Dynamic Power Step: No

Reduce Processor Speed: Yes

Automatic Restart On Power Loss: No

Wake On AC Change: No

Wake On Clamshell Open: Yes

Wake On Modem Ring: No

Display Sleep Uses Dim: Yes

Reduce Brightness: Yes

Hardware Configuration:

Clamshell Closed: No

UPS Installed: No

AC Charger Information:

AC Charger (Watts): 50

Connected: Yes

Charging: No