Battery life is not limited to i3 ->i7. The battery life should be comparable to an identical laptop with same hardware/usage. While the i3 is a higher performance CPU, it is more energy effiencent. But do not compare to a "solo" CPU, with only one processor, to a dual core Proc. i7 can be a dual core or a quad core proc (I think).
(1) Battery life is more dependent on the number of cells and the usage.
(2) Depending on usage (ie playing a dvd vs surfing the web), you can deduct upto 1 hour from "Advertized" battery life.
(3) Reason extended life batteries are available. Have a tosibia A205 and a A305. The A205 came with a 6 Cell battery pac, Bought a 9 Cell battery to replace it. The A305 came with a 9 Cell battery. I made sure that the A305 used the same battery pac as the A205.
(4) Manuf run time is a marketing tool that is deceptive, but legal, as it does not load the battery to the same level as a user might.
I agree, but since i5 and i7 are more powerfull cpu, they should upgrade battery to a fair time of use. I also heard that is there going to be like a second generation, because the material are made off, they do have leak of powder. There is also a rumor that I have not confirm my self, that if you upgrade a notebook from vista to windows 7 it shorten the life of the battery. This is not related to my main cocern but it is a take notice.
(1) It a trade-off performance vs battery life. I don't think they make extended batters for all models - I do agree that it would be nice to select at purchase a regular battery or pay the difference for an extended battery, But I don't think "Best buy" would like that Idea. It all in the marketing cost vs other brands' cost.
(2) I think they have found a better compond for batteries, but not sure of the cost and when available (Back of my mind.
(3) There was an artical on windows 7 vs battery run time, but I think that was fixed in a Win 7 update. For a laptop I prefer either XP or win 7 as vista was to bloated.