Q: iBook G4 battery problem

Had you tried to reset the Power Management Unit?

• Resetting PowerBook and iBook Power Management Unit (PMU) - Apple Support

...Sometimes, it may also be helpful to reset PRAM. (older Mac uses same reset as...)

• How to Reset NVRAM/PRAM on your Mac - Apple Support

Also the battery may actually be getting old, that series had lower battery life than

the later portable Apple computers who use different technologies. However if you

have a NewerTech battery from OWC macsales, and if it is less than a year old,

you may want to contact them and discuss the matter. Some other brands that may

be available for older PowerPC portable Mac iBook G4/PowerBookG4 if you locate

then, such as Anker, have reportedly been fairly good. Odd brands, are a mixed bag.

And another item that may be partially responsible for irregular charge/discharge or

strange behavior with battery and AC use, may be the DC-in Board. This is the port

and circuitry behind the port in the computer. So you may have any one or more than

one part that may be affected due to age & wear. Battery, AC Adapter, + DC-In Board.

Some idea of the complexity of the internal components in iBook G4 can be seen here:

• iBook G4 Repair Guides (all models) - iFixit:

https://www.ifixit.com/Device/iBook_G4

To locate a replacement AC adapter is another matter. Third party models do not

generally have the indicator light on the DC-out plug, if a generic design...

NewerTech 65W AC Power Adapter for Apple PowerBook G4, iBook G4 & G3

Clones may or may not be OK. These are different than later MagSafe...

• PowerPC-Based Mac notebooks: Identifying the right power adapter and power cord--US - Apple Support

• Mac notebooks: Troubleshooting power adapters with a Barrel-type connector - Apple Support

I have a few iBook G4 batteries that suggest they have 80+% charge, but really don't.

That, partly due to their age; two replacements from Apple some years under a recall

program they had at the time, they weren't long lived. I'm considering an OWC battery.

The replacement battery type and inventory number will vary depending on Display size.

https://eshop.macsales.com/search/batteries+for+iBook+G4 (12-inch + 14-inch iBookG4)

Sorry to have a magic talisman or other means of making the unit 'just work'

though some magic may seem to be involved, if stars are aligned just right.

In any event...

Good luck & happy computing!

From the looks of it ,you need to replace your battery