Monitoring Li-Ion Battery levle energry

[naderus]

I want to use a 8.4v Li-Ion battery for my AVr board and
monitor the battery energy like the mobile.It means I like
to show the user how long the battery will be work for him.
I only need to show 4 step (100% ,75%,50% and 25%) battery level.
I think I use AVR's A/D to chapture the battery voltage and current
but don't know how to get the battery level from them.
what is the best and cheap way to show battery level?

thanks.

 

[servicemann]

**broken link removed**

Note the application notes below.