Adapter always glowing orange

My refurbished G3 iBook (originally purchased 3/2006) has started acting strange recently. The adapter continually glows orange, indicating the battery is always charging. At one point I let the battery run down, plugged the adapter back in, and the problem seemed fixed for awhile, but it has started again. Now, draining the battery seems to make no difference.

When I wake the iBook up from sleep mode, the adapter glows green momentarily, then goes back to orange. Currently, the adapter is glowing orange, all but 2 segments on the battery level control strip are dark, the battery icon has no lightning bolt through it, and when I press the button on the bottom of the battery, all the green led's light up.