Are there any apps to diagnose a Macbook battery?

My girlfriend's battery won't last 1 second, so it obviously needs replaced.

But I just bought a new battery from Apple a few months ago and it seems to discharge extremely quickly. Are there any apps out there that would help me diagnose if I just need to buy another new one?

On my MacBook, if I opt-click on the battery in my menu bar, it gives me current the condition of my battery.

You can also use iStat to show the current state of your battery.

They are several solutions :

• coconutBattery, the most famous one.
• Watts seems nice even if I never manage to finish to calibration setup …
• Battery Health if you want a free one.

You can also use the built-in tool System Profiler to check your battery :

I can suggest some easy hint to inform you about the health of your battery: go to utilities > System Profiler select Hardware > Power > Battery Information

The third section is Health Information, where you can find out the current condition of your battery. As in the following screenshot, the Cycle count is 213, which means the battery has been discharged and recharged 213 times. And its current Condition is Normal.

Also, you can install Battery Health Monitor to get more information about your battery.

Also, it's a good read about the maximum Cycle count of your battery

While it's possible it's a bad battery - what programs are running on the computer? If you use Activity Monitor is CPU usage consistently "high" (say >50% in this case)?

Programs such as coconutBattery can give you the stats on your battery - telling you how much of a charge your battery still holds and how many load cycles have been done on your battery. If your current Battery capacity is under 25% it may very well be a good time to get a new battery. Under 10% for sure. If the new battery is less than 50% battery capacity in less than 6 months give AppleCare a call, they do have a warranty on their batteries but it's relatively limited.