Hello, everyone

I propose a new battery as a replica to choose.Shop at http://www.pcakkus.com because they are not so expensive and limited my budget for it.
I would like to know:

First What capacity holds as long when using NHC (program to dynamically overclock down). The application is primarily internet with wifi.
Second How difficult are the different sizes?
a) 4400
b) 6600
c) 7200
Third Do you have experience with battery-dealers?
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thanks