Which is better normal batteries or lithium?
and how to know what voltage required for my arduino board ?
MovieFan1995:
Which is better normal batteries or lithium?
It is impossible to answer that without knowing what they are to be used for.
and how to know what voltage required for my arduino board ?
It is clearly stated in the product specifications.
...R
how to calculate much is going to last?
Work out or measure how many watts your complete system uses on average. Then divide that figure into the capacity of the battery in Watt.hours.
With no information about what you want to power all anyone can say is that batteries with larger capacities will last longer.
Steve