Battery indicator question

I bought my iPod mini using the student discount last month. The 2nd generation minis have batteries that can be used up to 18 hours. But could I have somehow gotten the 1st generation one? Or could mine have come with the older batteries which can only be used for up to 8 hours?

I ordered the silver one so the color won't help me to distinguish its generation.

Is there some way to check whether mine is the 1st or 2nd generation iPod mini?

Thank you all for the responses.

After reading David's response I decided to pull some pictures of the 1st and 2nd gen. iPod minis from the internet and do some comparisons. I did notice the white-ish lettering of the silver mini.

My iPod mini has 4GB written on the back. And its serial number is P9800LL/A. But the trapad wording is noticeably darker. It's like a dark grey. Does this mean that mine is a 2nd gen. mini with an older trackpad? However I did notice its battery only can run about 6~8 hours.

Any ideas? Has this ever happened to anyone else before?

Thank you Buegie for providing me with those useful links. But those articles still do not address all my concerns.

I play my iPod mini in shuffle mode.
I turned off soundcheck (hopefully that'll help prolong my usage time a bit).
EQ and backlight have always been set to off.
Never set any alarm and checked that it is turned to off.
I always use the hold button to avoid accidental clicks.
I charge it using USB port and the cable it came with.
Never disconnected it when it said "do not disconnect".
I believe my songs are all MP3 so there shouldn't be problems with them.

Basically I've tried following all the "rules".

Here are some new minor questions/problems I've came upon recently:

1) When the ipod battery needs charging does the meter show some kind of sign? Other than it showing being empty.

2) Just the other day I used the ipod 'til a screen showed that it needs to be charged. I turned it off and tried to charge it with the USB cable. The ipod mini's screen froze when I connected it to my computer and the ipod drive didn't show up on my desktop. The mini shows that it's charging but the screen did not animate, showing only 25% charge. Then I waited for about 10 minutes and it came back to life again. Is this normal?

3) So I continued to charge it for about an hour then I left my computer to do something else forgetting that the ipod won't charge if the computer is in sleep mode... When I came back to check the computer was asleep and my ipod is off. I turned my computer on right away expecting the ipod to continue its charge but the screen shows it's full and it stopped animating. I've only charged it for about 1 hour and a full charge should take 4 hours. Can the ipod be fully charged in just 1 hour? From what I've read it shouldn't be.

4) Since then I've used the ipod for about 5 hours and now it needs to be charged again. During this usage my ipod would pause songs randomly, even when I'm using the hold button. I have to un-hold it and click play for the song to resume. I find this very odd.

I know this post is getting very long. But if anyone has any other ideas about why my ipod is behaving this way please comment. It would be great help.

My ipod mini is less than a month old and I hope to get these issues resolved so I won't have to take it to an Apple store 40mins away. It's kind of far.

So I thank you for your help in advance. And if any of these issues has showed up before in the forum please direct me to their post. I've since searched many other people's posts and they have yet solved my problems.