In April of this year, Apple replaced my 30GB iPod because of some battery issues and a couple other glitches. They sent back what looked like a new unit with what I assume was a new battery.

(I keep the EQ off and the backlight on for only 5 seconds)

Now, we're only 8 months later and the battery is junk. If I charge it plugging it into the wall, I can get 4-5 hours, but less if I scroll through songs and fast forward through them.
If I charge it with the firewire into my computer, I get less playing time and yesterday actually got 15 minutes after a day of charging!

It's now at the Apple store and they will test it tomorrow. They reminded me about how the battery can usually take around 300 charges/discharges, but in only 8 months, I know I haven't charged it that many times...
I told him that during work 4-5 days a week, I use the iCarPlay adapter to use it in the car (charger & FM Modulator). He said that could possibly be hurting the battery life. Does that sound right?