Picked it up on eBay for 7 bucks including shipping.I see. From what website you bought the battery from?
I got the 2800 Seidio extended battery and case combo. It works awesome. I'm still breaking in the battery, but still no complaints.
Do a full discharge and recharge once in a while to make sure battery sensor in the phone reads the battery state correctly.
Actually, that's the problem. See, android doesn't properly sense the actual life of the battery and gives incorrect readings of how much juice is left. When I first got the battery it was discharging after about 5 hours. I was really mad. To fix this though all you need to do is reboot your phone. After a reboot the battery shows about 80 to 100% again.
the battery is great and has been lasting me 2 full days with medium use and leaving it on over night. But... because you cant trust the battery meter and you always have to reset your phone, I give it a 2/5 *'s (cause you never know if the phone is actually dead, or just needs another reboot). Its an amazing product and not seidio's fault the battery meter doesn't pick up the "battery on steroids" in its holster. If there's no fix with froyo I'm gonna return and just carry around an extra battery.