t21 battery life?

[renhui]

I recently purchased a used t21 lion battery off ebay, it has design capacity at 42wh, and shows a full charge capacity at 32wh. However, the battery jumped from 40% to 5% in real use, and I have done two regeneration cycles to recalibrate the battery meter, nothing!
Also, I tried to benchmark the battery by playing a vdieo off the harddrive with brightness set at 5. it only lasted a little bit over 1 hrs, is that normal for a battery which still holds 75% of full charge?
My old battery only held 50% of full charge and lasted me more than 100mins! (but it died all of a sudden.)
Thank you very much.

[TonyJZX]

What is the build date, first use and current health of your 'new' used battery?

[renhui]

here is what Battery Information reports:
manufacturer name: Panasonic02
manufacturer date: 2004-04-28
first used date: 2004-10
design capacity: 42.12wh
full charge capacity: 31.17wh
current health status is "good".
Thank you.

What is the build date, first use and current health of your 'new' used battery?