iPod touch ISO crash's when battery runs out

I have a 4th generation iPod Touch, the first day i got it a gave it a full charge then drained it all the way down to it shutting it self off via having it continuly record to the last min or so, once the batter was depleted. from what i was taught a lithium battery wont hold a good charge till its completey drained. i plug it to my mac mini to start the charge and opened itunes and i got a waring that the ipod had crashed and that it would restore the ISO, the worst case i had was that when i crashed it again the ipod went to factory restore and i had to have itunes put all the music back on along with apps..

I miss the simple OS for the 1st generation, it lacked all the cool stuff but in my mind a little more stable