In some respects, life as a laptop-carrying frequent flyer has gotten a little easier. Exhibit A: Though far from commonplace, it's not freakishly bizarre anymore to find a power port at your airplane seat--even in coach. Virgin America and American Airlines are among the most generous airlines in terms of supplying power ports to passengers.

But it's still way too easy to run out of juice in flight, or during the course of a long day away from a wall socket. Here are some tips for keeping your laptop running as long as possible when you're on the go.

Ditch the Peripherals, Tweak Settings

When you're on the road, you can significantly conserve battery power by dimming your laptop screen's brightness. Make sure there are no CDs or DVDs sitting in your optical drive, and don't connect any USB peripherals--all power hogs. Turn off Bluetooth, Wi-Fi, and 3G networking (you have to do that in flight anyhow).

Also, tweak your laptop's power settings to conserve your battery. For example, in Windows Vista, go to Control Panel, Power Options and select the "Power saver" setting You can adjust the "Power saver" settings, if you want, or create your own power plan.

Buy a Second Battery

Many laptops today can run off two batteries. When the juice from the primary battery runs dry, the auxiliary kicks in. In most cases, the primary battery comes with the laptop; the second is an optional purchase. For example, HP's EliteBook 6930p promises up to 24 hours of use from one charge--but only if you attach an optional, external 12-cell ultra-capacity battery pack ($189) as a secondary battery to augment the laptop's internal, primary six-cell battery (There are other requirements, too, such as the need to downgrade to Windows XP.) Keep in mind that second battery packs, sometimes also called battery slices often add bulk and weight to your laptop.

Another option: Buy a portable battery pack. I like the Duracell Powersource Mobile 100 (about $110 and up online) because it lets you power a variety of devices, such as laptops, cell phones, portable DVD players, and video cameras, using their own power cords. By comparison, some portable power rechargers require special tips or cables to recharge your gear. The Duracell Powersource can also recharge two USB devices simultaneously with your laptop.

Get to Know Battery Specs

When buying a new laptop or a second laptop battery, pay attention to the power specs. Generally speaking, you need to know how many cells the battery has. The more cells, the longer the battery can last on a charge. For example, a 12-cell battery is designed to last much longer than a six-cell battery. Alternatively, the specs might list Watt-Hour rating, or WHr. The higher the number, the longer your battery should last. Some computer makers, such as Apple, describe laptop batteries in terms of WHr, while others use cells.