I am a college student and I use my laptop in lectures to take notes or (in the event of a boring lecture) work on assignments for other classes. With only vim and a web browser open, I still only get about 4 hours of battery life. What can I do to improve this? What do I need to know to buy a better battery for it?
Power Saving Options
One of the first fixes for laptops is adjusting the screen brightness. The backlight on the LCD draws quite a bit of power.
Your next step is to evaluate your power settings. In Windows 7, it's in the Control Panel > Hardware & Sound > Power Options.
In Windows 7, "power plans" are a pre-built group of settings that determines how your computer manages it's power consumption. Many OEM manufacturers will include some custom ones, but there are usually three included in Windows 7 by default: Balanced, High Performance and Power Saver. You may find that your laptop is using High Performance and simply changing it to Power Saver will improve your battery life.
If you are already using the Power Saver plan, switch to it. By default, it will configure your power settings for the following:
You can customize each power plan by clicking "Change Plan Settings". More advanced options are available in the "Change advanced settings menu".
Rule of thumb: if your battery life doesn't improve after your usage has improved, then it's time to replace it.
If you have done all you can to improve your battery life but it's still not acceptable, replacing it is just a matter of getting the correct model.
Always rely on what the manufacturer says is compatible. Third party manufacturer batteries may work, but the most you can rely on is customer reviews in that case.
On your computer's manufacturer website, you can usually search by your model or serial number. From there look up replacement parts, and it will list which battery models are compatible.
Battery life is rated in mAh (milliampere-hour). It's a unit that describes the available current at the rated voltage for one hour. In layman's terms, the higher the mAh rating, the longer your battery will last on a given charge when it's new. Keep in mind that lithium batteries tend to lose their ability to hold a charge over time.
Turn off bits of your laptop, turn down the screen brightness, make the hard-drives sleep after short periods (assuming you're still running a disc based system). Disable wireless that you're not using (blue-tooth, 3g, wifi).
Make sure you're not running needless services, run your browser without heavy plugins (include a flash/ad blocker). Make sure you're not using the GPU (turn of the effects in Windows).
Alternatively, dual-boot to a slim Linux build.
if the battery is removable check the part number and see if someone makes a larger battery for it. Keep in mind that some manufacturers like Lenovo only like their own batteries and will complain if they aren't the genuine article. I have two batteries for my laptop and simply swap them out when I need to keep going...