As I’m writing this post at Starbucks, my laptop has only 28 minutes of battery life remaining. The lesson: your notebook is only as good as its battery. As I’m hunting around for a plug, I now realize that even the 5-hour battery life of my MacBook Pro maybe isn’t always enough. Finding the right balance between performance, battery life and cost (netbooks aren’t always practical) is a tough call. Check out PC Fastlane’s picks for the longest battery life laptop and never worry about finding a plug again.

First off, it’s important to note that manufacturer battery life specifications are always overstated. This list of laptops with the best battery life uses manufacturer specs under the assumption that all computers makers have equally unrealistic testing methodologies. Research real-world battery life tests on your own before buying to find out how long a battery will last in the real world.

Lenovo ThinkPad X220

The Lenovo X220 ultra-portable laptop may be close to netbook size at 12.5″, but you can’t beat its quoted 15-hour battery life. Adding an external ThinkPad battery pushes this figure up to 24 hours. This is the best laptop battery capacity I’ve ever seen, though prospective buyers should factor in the small size of the ThinkPad X220 and weight of the external battery pack. A X220 convertible tablet with a somewhat shorter battery life is also available. Besides plenty of a juice, the $899 starting price tag gets you an Intel Sandy Bridge Core i3 (i5 and i7 available) CPU, an SSD, as much as 8GB RAM and a 1366-by-768-pixel IPS screen. Forgetting your charger at home certainly isn’t a problem with this longest-battery life laptop.

MacBook Air

Rated for up to 7 hours, the 2.4-pound Apple Macbook Air is the sexiest best-battery life laptop in this guide. It packs large battery capacity in a slim package. Owners give up the ability to remove the battery in return for the small form factor, however. Bringing a spare battery with you is not an option with the MacBook Air. All models feature a dual-core Intel i5 processor and SSD. The cheaper 11.6″ LED screen version can be had for under $1000 with 2GB RAM, while the more versatile 13″ MacBook Air models start out at around $1200. The best configurations have a 256GB SSD and 4GB RAM, which unfortunately is not upgradeable. Consider a MacBook Pro if you want more speed and upgradeability and a cheaper price. It’s a fair competitor in the longest battery life laptop game with a 5-hour rating.

Photo | Travis Isaacs

HP EliteBook 8460p

The HP EliteBook 8460p battery life is simply out of this world. Configured with an upgraded battery, this business laptop can flip through Excel spreadsheets and answer emails for up to 32.5 hours. Options include a 14-inch screen, Intel Core i7 processor, up to 16GB RAM and AMD Radeon HD 6470M discrete graphics. The HP EliteBook 8460p’s price starts at $959. Business users will find it to be a very versatile companion indeed. It is by definition a best-battery life laptop.

Toshiba NB505

Those on a budget for a laptop with the best battery life should check out the Toshiba NB505 netbook. It’s $250 price point won’t break the bank, but it’s long battery life of 8 hours is a winner. The 10.1″ screen is tolerable for Web browsing and basic document editing. Other specifications include an 1.66 GHz Intel Atom N455 processor, 250GB hard drive and 1GB RAM. Although the Windows 7 Starter Edition that ships with the Toshiba NB505 isn’t resource-intensive, upgrading the RAM to 2GB wouldn’t be a bad idea.

Keep in mind there are hundreds of notebook computers on the market, so there are plenty of laptops with long battery life out there. If your current system doesn’t have the best battery life, consider energy-saving tips such as turning on power-save mode, turning down the display brightness, closing applications running in the background and disabling unused devices such as modems and optical drives. Laptop batteries don’t last forever regardless of how expensive your computer is. Expect to replace your battery after 2-3 years of use to maintain the best battery life possible.