Battery Life?

[Seymour J. Wolfson]

I have one of the original TiPB when they first came out, and, as I 
recall, they were supposed to last about 4 hours on the battery.  I 
have been doing OK for a long time, but most recently I noticed that 
after about 1.5 hours, the battery gives out.  In fact it happens so 
fast, I do not even have enough time to shut it down before it goes 
into the coma state.
Is this what should be expected or is this battery dying?
-- 

Seymour