Laptop Power Management issue - battery charging

[djpenguin]

I have an ASUS S5Ne laptop computer with gentoo installed, and almost everything works just great. I used the gentoo power management docs and the S5Ne page at the gentoo-wiki to get everything going. There's only one small quirk, but it's a strange one. When the laptop is plugged in, the battery will charge to full capacity, then it will stop charging. After that, the system will discharge from the battery (very slowly...it takes days and days) without taking any power from the AC adapter until the AC cord is unplugged and replugged, effectively cycling the computer from the default runlevel to the battery runlevel and back to the default runlevel.

What's going on here? Is there a way I can get the machine to use the AC adapter instead of draining the battery slowly?
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