When looking at a comparison of an Intel i3-4370, and an Intel i7-4790k (coincedentally, the score difference is about double...), you'll notice that the 4790k actually gets about double performance at 88W, in comparison to half the performance of the 4370 at 54W. This shows that the efficiency of a 4790k is actually greater than a 4370. Part of the reasoning behind that is because while the cores and the threads double (As well as the Smart Cache), the GHz ratio lowers overall, even though the 4790k has a higher clock rate. This makes the efficiency of the CPU much better than the i3 being compared.
So realistically, the i7 is actually a better option when using CPU intensive tasks, while the i3 is preferable when doing simple tasks such as browsing online. So while the maximum watt draw of the i3 is a flat amount, the i7 can potentially draw 30W more, which could cause a significant drop in battery life.
Another issue with watt usage could be because of the extra 2 cores. The i7 would basically be keeping both cores powered and ready, which could cause some extra watt usage even when not needed.
Look into Power Options, as well as CPU throttling and turning off cores if the extra Watt usage is that much of a bother.
So realistically, the i7 is actually a better option when using CPU intensive tasks, while the i3 is preferable when doing simple tasks such as browsing online. So while the maximum watt draw of the i3 is a flat amount, the i7 can potentially draw 30W more, which could cause a significant drop in battery life.
Another issue with watt usage could be because of the extra 2 cores. The i7 would basically be keeping both cores powered and ready, which could cause some extra watt usage even when not needed.
Look into Power Options, as well as CPU throttling and turning off cores if the extra Watt usage is that much of a bother.