laptop battery and... ubuntu?

[helane]

i have laptop compaq presario v3000. just a couple of weeks ago i 
switched to new ubuntu, and then last week my battery started showing as 
"old/broken". it would charge but would not give me only about an hour 
on it. i used the laptop extensively in the last year so thought it was 
an old battery. i bought a new certified one - 12 cell, hoping it would 
give me even more time than the last one. i plugged it in, it came 50% 
charged showing 50 minutes. it charges fast... it went to 77% in 20 
minutes but now shows again 55 minutes on 77%. the percentage seem to go 
up the time does not as fast... now it went to 80% still showing 55 min. 
on the old battery i used to get 2.5 hrs on the new one i was supposed 
to ~5 hrs. not sure if something else is broken, or the linux shows 
wrong time... any ideas? i really appreciate it. spend a lot of money on 
a new battery... no happy about it.

thanks
helane.