MacBook Pro Late 2011 Battery Problem

Hi everyone,

I have a late (December) 2011 MacBook Pro 15" with the latest OSX installed with updates from Apple. I've had this since it was new and I've kept it mostly plugged in. The battery is apparently in really bad shape, even though the stats on the battery are:

Full Charge Capacity: 6156

Cycle Count: 135

Condition: Normal

Battery Installed: Yes

Amperage: 3078 (it's currently charging...)

Voltage: 12189

My question is this: Is my battery shot to ****? Because when I unplug it to drain it down, or I'm out of the house with it unplugged, it will go down to about 25% and then it will shut off as if it's run out of power. When I plug it back in, it starts charging up again "from scratch" so to speak. So it's misreading about 25% power on the battery or something. Not quite sure why.

I have done a PRAM reset in the past a few times, to no avail. It's been like this for the last year and a half or so. Is there a way for me to reset it so that when the battery is drained, it reads at 0%? Is there something which I can do about it?

Any good battery advice for me at this point would be very welcome.

Thanks in advance.