I have the latest Ipod touch (for about 2 years). It never fully charges. It always shows the lightning bolt when plugged in. The battery drains in about 2 1/2 hours. I'm trying to recalibrate it but it never says it is completely charged.
To be honest I have one that does the same thing. The battery in it is horrible. Depending what you are doing on it that amount of time per charge can be accurate. Watching video kills it quick and so does gaming.