For the phrase iBook Clamshell battery problem Google.com returns 111,000 links. It should be the obvious sign that G3 iBooks used to have a lot of trouble with their batteries. And the problem often was not in the battery itself.
 
The general case looks like this: one day you purchase a new battery for your iBook Clamshell, put into the tray, close the lead, start the iBook. You battery shows 0% and you impatiently wait till it charges. But suddenly in about 10 minutes battery icon shows you "X". That can't be a good thing you sagest but hoping for best start trying usual routing like taking battery out and back, turning on and off a computer, etc. But always you get the very same result - ten minutes with 0% and then "X" - iBook considers its battery tray empty despite having there brand new, or recently fully functional battery.
 
But don't rush to reach for a check to claim a warranty or throw battery away (it have to be recycled! :).
 
Having this scenario playing by my own with iBook Clamshell SE I dug the Internet for days looking for some workaround. And there were plethora of them but non of them helped. Battery was rejected by iBook again and again. What a drama...
 
Bypassing long research I will bring you to the theoretical understanding what might cause such a problem: Power Management Unit controller registers has flags... lats make it easier... PMU don't see a battery because can't get itself configured in order to recognize a battery state properly. And to reset PMU you need to know one trick. 
 
Holding reset button for 15 secs as Apple recommends may not be enough because Clamshell series does not posses PRAM PMU Battery like later models. They have a PRAM CAPASITOR! Aha! Experimentally I discovered that indeed after reseting PMU according Apple instruction certain voltage remain on the motherboard. I sagest that residual voltage feeds PMU and keeps it in a dump configuration.
 
Solution is simple. Unplug AC adapter. Pull the battery off. And go have some coffee. In about 30 minutes or so PRAM Capacitor should discharge fully. 
 
Then do as followed:

(Yo may check original post at http://www.applefritter.com/node/18613)
 
1) Reset the PMU. With the computer off (and battery pulled out!), use a straightened paper clip to push down the reset button "under the grille" near the power button for 5-10 seconds (the proper technique for this model). Your PMU has been reset.
 
2) Reset the PRAM. Start up the machine, then hold down the following 4-key combination immediately after the startup chime: [Apple]-[Option]-[letter P]-[letter R]. I usually find it helpful to hold [Apple]-[Option]-[letter R] with my left hand, press the power button with my right hand, then immediately press the [letter P]. Hold down all four keys until the Mac has chimed 3-4 times. When you let up, the Mac should start up normally. You'll have to shut it down again for the third step.
 
3) Reset the NVRAM. Start up the machine, then hold down the following 4-key combination immediately after the startup chime: [Apple]-[Option]-[letter O]-[letter F]. Hold down all four keys until the machine boots up to a grey screen with text: this is Open Firmware mode. NOTE: Be very careful what you do here! It's easy to mess things up in Open Firmware very quickly if you don't know what you're doing! Type the following commands exactly as they're written here, and follow each command by pressing the [Return] key:
 
reset-nvram
reset-all
 
Your NVRAM has been reset, and your Mac will now restart itself normally.

Put the battery back.
 
Now you can go about the task of completely draining, then recharging, your battery. Go to your Apple Menu>System Preferences>Energy Saver. Select "Battery" instead of "Power Adapter," and set the all the sliders to not sleep, ever. Period.
 
Now stick a CD or DVD in the drive and open iTunes. Turn on Repeat mode and play it indefinitely (you might want to pick one you actually like ...).
 
Unplug the power adapter and let the iBook run until it goes into low-power deep sleep. This could be the 5 minutes, or it could be the full 2 hours.
 
Once you're in deep-sleep mode, plug in the power adapter and allow the battery to charge for however long it takes -- overnight would be ideal. Then you can test the battery under normal use conditions.
 
Sometimes, the PMU becomes confused and either (1) reports a charge higher than is actually on the battery, causing the charging circuit to turn off prematurely, (2) reports a charge lower than is actually on the battery, causing the computer to shut down or deep-sleep prematurely, or (3) some combination of these symptoms.
 
By resetting the PMU, the PRAM, and the NVRAM, the Mac should now have a clean slate and be forced to "relearn" when the battery is fully drained and fully charged. A full drain-and-charge cycle should help it find these parameters.
 

Repeat as needed :) 
 
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The author does not bear any responsibility for any result of applying stated above recommendations. Your results may vary and are not guarantied. Any manipulations you do with your computer you do at your own risk. 


Sergi B.