Oliver chewed on my laptop’s power cord last week, so I took my visit to the Apple Store as an opportunity to ask about my battery. A full charge was only giving me about an hour of use. This is the second battery I’ve had for my three-and-a-half-year-old computer, and I was a little upset at the idea that I’d have to replace it again.

It turns out that my computer was constantly trying to wirelessly connect to a printer that didn’t even exist anymore. It had been doing this for a whole year! This sucked up a lot of power, slowing down my computer and making my battery run down faster. (I could have figured this out myself if only I’d thought to look at the Activity Monitor.)

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The guy at the Apple Genius Bar told me that my battery is about 2/3 of the way through its useful life. On average, after 300 cycles the full charge drops to 75%. But I can extend my battery’s life by reducing the number of cycles it goes through (and saving energy in the process). There are a few ways that I can do this:

1. Keep it 20-80% charged at all times. Old nickel-cadmium batteries regularly needed to be fully discharged, then fully recharged. However, that’s not necessary for the lithium-ion batteries that laptops now use. Instead, try to keep the charge somewhere in the middle. If the estimated power has gotten inaccurate, it will be necessary to completely drain it and completely charge it again, to reset the charge meter, but this doesn’t need to be done often. I’m not sure if I can do this consistently, but I’ll try.
2. Use the computer on a hard surface. Soft surfaces like pillows or your lap block proper ventilation. This makes the fan work harder (using more energy) and overheats the battery. I’ve got mine on a hardcover book right now.
3. Turn the computer off to charge it. Or, if you’re going to use your computer while plugged in, pull out your battery. This prevents it from overheating. It’s not very convenient for me to charge the computer where I use it most (on the couch), so this isn’t a major problem for me.
4. Don’t overcharge the battery. I admit to usually charging overnight, and I’m not sure I can conveniently stop that. . . . I’ll try.
5. Update your software. Apple, at least, says that their updates sometimes improve battery performance.
6. Turn off unused applications and wireless connections. They consume power even when not in use.
7. Improve your energy settings. Put your hard drive to sleep after a short amount of time (say, 7 minutes) and your display to sleep after a minute. Keep your monitor’s brightness level low. The less energy you use, the longer your battery will last.

If there’s one common thread here that I’m going to keep in mind, it’s that heat eats batteries. My computer being warm will be a good reminder to me that I need to do something different in order to preserve my battery.

All the things that increase your battery’s lifespan also reduce your computer’s energy use. Laptops are already designed to use far less power than desktop computers, and by doing this we can make them even more efficient. Bonus!