Powerbook G4 500 won't boot from battery only

Question

Hi,
I have a Powerbook G4 500 Ti (running OS 10.4.8 that will not boot from just the battery without the powercord attached. I have tried several different batteries and the same results.
Sometimes under "About this Mac" the battery show's it's there but most of the time it doesn't show a battery and an X appears on the desktop.
What I've done - replaced the battery with a fully charged one from a working PB, reset the PMU, Reset the Pram, Cleaned the contacts on all batteries and in the battery bay, Reseated the Airport card, Down loaded the latest Apple updates today and loaded them.The computer runs great with just the powerchord and sometimes the battery icon shows a picture of a plug, but then it reverts to the X.
Another problem, I have a working Airport card installed from another machine and it doesn't show up in the About this Mac window I get Airport Card: No INFORMATION FOUND that it is installed. Could this be related and also can a dead PRAM battery cause this? Any help would really be appreciated I've tried everything. Thanks for your response in advance.

Answer 1

Hi, Opie. A dead PRAM battery will generally prevent a Tibook from starting at all, with or without the AC adapter or a main battery in place. Therefore, I doubt that that's your problem.
Your Airport card cage and your battery are both connected (separately) to the Powerbook's main logic board. it is possible for those connections to work loose over time, or to be hindered by oxidation on the contact surfaces. You can try disconnecting and then reconnecting each of them several times to wear away oxidation and make sure the connectors are properly seated.
This page is the starting point for a complete, well-illustrated set of take-apart instructions for the 500MHz Tibook. The bottom illustration on the page that shows how to remove the keyboard shows the battery connector: a large white plug with several multicolored wires attached, directly beneath the keyboard's left-hand Command (Apple) key. The last illustration in the instructions for removing the Airport card shows the card's connector: a rectangular tan or orange tab at the right-hand end of the flex cable that is connected to the Airport card socket. While you have the bottom cover of your Tibook off, check to make sure the card is firmly seated in its socket and that the flex cable is solidly connected to the logic board.
Another possible reason for the battery's not being detected sometimes: Some 400MHz and 500MHz Tibooks had an ill-fitting battery: it slopped around in the battery compartment and could lose contact. Apple offered for some time to install free of charge a small shim that took up the slack inside the battery compartment and kept the battery pressed against its contacts. If that correction was never made in your Tibook, or if the shim has fallen out or shifted from its proper position, your Tibook may be suffering from the original problem now. Check to see that there is no movement of the battery once you snap it into position in the battery compartment. If there is any, post back for guidance on making and installing a shim. (Apple long since discontinued the repair program, and it's a simple thing to make yourself.)