HP Laptop won't run off Battery

Hello. My girlfriend has an HP Pavilion ZE4400 (I think that model number is right). Anyway, The battery hasn't ever worked on it since she bought it used and her dad bought a used battery off Ebay to replace the bad one. However, Windows reads the battery at 2% after about 5 minutes when it was previously 100%. I pulled out the battery and pushed the little test button and it shows a full charge....so is the battery faulty and I should just look for a brand new one or is there a possibility that the laptop itself has an issue with being powered from the battery?

You can use geekspeak in your response...I can interpret it just fine :)

The battery is dead, get a new one.

Actualy, there maybe a fault with the lap top.

We got several HP Pavilions for the senior management, and all of them have had to go back for repairs because of exactly the same issue described above.

Hmm...IIRC I have seen the same fault on a HP Pavillion as well, but the person experiencing the problem never resolved it. As it isn't under warranty, I can only suggest visiting the manufacturers website and upgrading all your firmware.

As it isn't under warranty, I can only suggest visiting the manufacturers website and upgrading all your firmware.

Ok, Will do. My girlfriend's dad went ahead and got another battery off ebay (a new one this time) and I guess if updating the firmware solves our problem then we'll just have a spare battery.

Thanks for the input so far as I know very little about laptop-specific issues.

Edit: I thought I should metion this: I tried another little experiment with the battery a couple days ago. I removed it from AC power and tried to boot the laptop off the seemingly fully charged battery. It booted, but it barely made it past the windows login screen (I got a very brief glance at the desktop) before it died. I Then removed and tested the battery again--it showed a full charge. I tried to re-boot the laptop but no luck on the second time. This makes me feel that I should lean towards a faulty battery...but I will update the firmware while waiting on the new battery anyway.