3. Run Time

A battery's run time depends on three main factors: your usage habits, the notebook's components, and the battery itself.

Light activities such as Web surfing and office apps will give you much longer run time than multimedia tasks will, such as movie playback and 3D gaming. Indeed, the differences in run times can be staggering when using my own laptop, the HP dv4, with its extended 12-cell battery. I can get five solid hours of online surfing, for example, but that battery time gets cut down to just over four hours for movie watching and only two and a half hours of gaming. If you tend to take breaks frequently while you work, you may find that your battery lasts longer than if you work constantly, since the notebook will run on idle more often. Of course, you should check your Windows power settings and make sure to have “max battery” enabled to get the most from your battery.

When looking at hardware, higher-end components are not always battery friendly. Take Intel’s mobile Core 2 Duo CPU. Intel’s T-Series processors have a 35 W thermal design power (TDP) rating, but its similar speed P-Series processors run at just 25 W. With 10 W less power, there is more juice left in your battery. In a similar fashion, integrated graphics will consume less power than dedicated graphics processors will because of the relaxed feature set. If your display is an LED backlit screen, it will use less power than the same display that is non-LED. Alternatively, opting for a more expensive, higher-end solid-state drive (SSD) drive that uses 1.5 W will also boost your battery times compared to regular mechanical drives that typically run at 2.5 W.

If you intend to wring every bit of power out of your notebook’s battery, you should thus take these hardware issues into consideration when configuring your notebook.

Quoted battery run times are also almost never what you end up getting in real-life conditions. That’s because manufacturers will run a common synthetic benchmark, such as MobileMark2007, in order to establish measurable comparisons between different batteries and different notebooks. That’s good when trying to compare a Sony notebook to a HP, but the catch is that a manufacturer’s testers will often perform these benchmarks on a model that has the minimum hardware that the OEM sells, while using its biggest battery under predefined settings, and quote a simulated maximum battery time. So don’t be surprised if that eight-hour rated battery only gives you six to seven hours in the real world.

Finally, while it is beyond the scope of this article, the practice of “undervolting” can also yield significant increases in battery times. Undervolting is the technique of lowering the CPU operating voltage at a given clock multiplier in order to consume less power. Results have shown that undervolting offers up to 25% longer performance, which translates into a full hour or more of batter life in some cases. And unlike overclocking, undervolting is nearly foolproof as the worst thing that will happen is that you get the infamous Blue Screen of Death (BSOD). Two great side benefits to this trick are that you will also get an incredibly quieter and cooler running notebook. If you’re interested in undervolting techniques, let us know in the comments section of this article.