Re: MacBook Pro Battery/Charging Issues

Lately I've been seeing some odd behavior when it comes to battery
life and charging for my MacBook Pro (MB133*/A). None of the behavior
is perfectly consistent, but here's a few things I've seen more than a
handful of times:

1) Battery life indicator estimates don't seem to be particularly
accurate: I may start with an hour and a half of charge, and find 20
minutes later that I'm being given the 10 minute warning.
Subsequently, I may find that the battery operates for another half an
hour.

2) Sometimes when I operate it unplugged, the battery life indicator
simply says "10:00" and doesn't change for some time.

3) Sometimes (in fact, at the moment) even though the machine is
plugged into a working outlet, I get "Not Charging" from the battery
indicator. I might expect "Charged," given that the power cord is
giving me a green light and the battery's hardware indicator lights up
to all five levels when pressed, but that's not what I see.

4) Sometimes even when battery hardware indicator shows full charge
and/or the software indicator shows time remaining, I'll see sudden
hard shutdowns, like you would from a desktop that's suddenly
unplugged, rather than the sleep process you usually see from a
drained laptop.

The machine's just about 20 months old, original battery, so I
wouldn't be surprised if the battery needed replacement. However, some
of the symptoms here seem unusual compared to past experiences I've
had when batteries inevitably wear out. Could I have a problem with
either (a) my  charger or (b) some kind of on-board hardware that
regulates charging behavior?